CALIFORNIA 2010 - IAPMO Group California Plumbing Code/Chapter 05.pdf · 507.3 Indoor Opening Size...

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Adopt only those sectionsthat are listed belowChapter/Section508.2 X X X

692010 CALIFORNIA PLUMBING CODE

CALIFORNIA PLUMBING CODE – MATRIX ADOPTIONTABLECHAPTER 5 -WATER HEATERS

70 2010 CALIFORNIA PLUMBING CODE

Part I

501.0 General.The regulations of this chapter shall govern the construction,location, and installation of fuel-burning and other waterheaters heating potable water, together with chimneys, vents,and their connectors. The minimum capacity for water heatersshall be in accordance with the first hour rating listed in Table5-1. Design, construction, and workmanship shall be in con-formity with accepted engineering practices, manufacturer’sinstallation instructions, and applicable standards and shallbe of such character as to secure the results sought to be ob-tained by this code. No water heater shall be hereinafter in-stalled that does not comply in all respects with the type andmodel of each size thereof approved by theAuthority HavingJurisdiction.A list of accepted gas appliance standards are in-cluded in Table 14-1.

502.0 Definitions.502.1 Appliance Categorized Vent Diameter/Area. Theminimum vent area/diameter permissible for Category I ap-pliances to maintain a nonpositive vent static pressure whentested in accordance with nationally recognized standards.[NFPA 54:3.3.7]502.2 Chimney (See also Gas Vent, and Venting System).One (1) or more passageways, vertical or nearly so, for con-veying flue or vent gases to the outside atmosphere. [NFPA54:3.3.17]502.3 Chimney, Factory-Built. A chimney composed oflisted factory-built components assembled in accordance withthe terms of listing to form the completed chimney. [NFPA54:3.3.17.2]502.4 Chimney, Masonry. A field-constructed chimney ofsolid masonry units, bricks, stones, listed masonry chimneyunits, or reinforced portland cement concrete, lined with suit-able chimney flue liners. [NFPA 54:3.3.17.3]502.5 Chimney, Metal. A field-constructed chimney ofmetal. [NFPA 54:3.3.17.4]502.6 Combustible Material. As pertaining to materials ad-jacent to or in contact with heat-producing appliances, ventconnectors, gas vents, chimneys, steam and hot water pipes,and warm air ducts, shall mean materials made of or surfaced

with wood, compressed paper, plant fibers, or other materialsthat are capable of being ignited and burned. Such materialshall be considered combustible even though flame-proofed,fire-retardant treated, or plastered. [NFPA 54:3.3.65.1]502.7 Direct-Vent Appliances. Appliances that are con-structed and installed so that air for combustion is derived di-rectly from the outside atmosphere and all flue gases aredischarged to the outside atmosphere. [NFPA 54:3.3.6.3]502.8 Flue Collar. That portion of an appliance designed forthe attachment of a draft hood, vent connector, or venting sys-tem. [NFPA 54:3.3.45]502.9 Gas Vent, Type B. Avent for venting-listed gas appli-ances with draft hoods and other Category I appliances listedfor use with Type B gas vents. [NFPA 54:3.3.105.2.2]502.10 Gas Vent, Type L. A vent for venting applianceslisted for use with Type L vents and appliances listed for usewith Type B gas vents. [NFPA 54:3.3.105.2.4]502.11 Indirect-Fired Water Heater. A water heater con-sisting of a storage tank equipped with an internal or externalheat exchanger used to transfer heat from an external sourceto heat potable water. The storage tank either contains heatedpotable water or water supplied from an external source, suchas a boiler.502.12 Vent. A passageway used to convey flue gases fromthe gas utilization appliances or their vent connectors to theoutside atmosphere. [NFPA 54:3.3.103]502.13 Vent Connector. The pipe or duct that connects afuel-gas-burning appliance to a vent or chimney. [NFPA54:3.3.106]502.14 Venting System.Acontinuous open passageway fromthe flue collar or draft hood of a gas-burning appliance to theoutside atmosphere for the purpose of removing flue or ventgases. [NFPA 54:3.3.96.6]502.15 Water Heater. An appliance for supplying hot waterfor domestic or commercial purposes. [NFPA 54:3.3.55.7]

503.0 Permits.It shall be unlawful for any person to install, remove, or re-place or cause to be installed, removed, or replaced any waterheater without first obtaining a permit from the AuthorityHaving Jurisdiction to do so.


CHAPTER 5WATER HEATERS

TABLE 5-11

FIRST HOUR RATING

Note:1 The first hour rating is found on the “Energy Guide” label.2 Non-storage and solar water heaters shall be sized to meet the appropriate first hour rating as shown in the table.

Number of Bathrooms 1 to 1.5 2 to 2.5 3 to 3.5

Number of Bedrooms 1 2 3 2 3 4 5 3 4 5 6

First Hour Rating,2 Gallons 42 54 54 54 67 67 80 67 80 80 80

504.0 Inspection.504.1 Inspection of Chimneys or Vents. This inspectionshall be made after all chimneys, vents, or parts thereof, au-thorized by the permit, have been installed and before anysuch vent or part thereof has been covered or concealed.504.2 Final Water Heater Inspection. This inspection shallbe made after all work authorized by the permit has been in-stalled. TheAuthority Having Jurisdiction will make such in-spection as deemed necessary to be assured that the work hasbeen installed in accordance with the intent of this code. Noappliance or part thereof shall be covered or concealed untilthe same has been inspected and approved by the AuthorityHaving Jurisdiction.

505.0 Water Heater Requirements.505.1 Location. Water heater installations in bedrooms andbathrooms shall comply with one of the following [NFPA54:10.28.1]:(1) Fuel-burning water heaters may be installed in a closet

located in the bedroom or bathroom provided the closetis equipped with a listed, gasketed door assembly and alisted self-closing device. The self-closing door assemblyshall meet the requirements of Section 505.1.1. The doorassembly shall be installed with a threshold and bottomdoor seal and shall meet the requirements of Section505.1.2. All combustion air for such installations shallbe obtained from the outdoors in accordance with Sec-tion 507.4. The closet shall be for the exclusive use ofthe water heater.

(2) Water heater shall be of the direct vent type. [NFPA54:10.28.1(2)]505.1.1 Self-Closing Doors. Self-closing doors shallswing easily and freely and shall be equipped with a self-closing device to cause the door to close and latch eachtime it is opened. The closing mechanism shall not havea hold-open feature. [NFPA 80:6.1.4.2]505.1.2 Gasketing. Gasketing on gasketed doors orframes shall be furnished only in accordance with thepublished listings of the door, frame, or gasketing mate-rial manufacturer. [NFPA 80:6.4.8]Exception: Where acceptable to the Authority HavingJurisdiction, gasketing of non-combustible or limited-combustible material (See NFPA220, Standard on Typesof Building Construction) shall be permitted to be ap-plied to the frame, provided closing and latching of thedoor are not inhibited.

505.2 Water heaters of other than the direct-vent type shallbe located as close as practical to the chimney or gas vent.[NFPA 54:9.28.1.2]505.3 Clearance.

505.3.1 The clearances shall not be such as to interferewith combustion air, draft hood clearance and relief, andaccessibility for servicing. Listed water heaters shall beinstalled in accordance with their listings and the manu-facturer’s instructions. [NFPA 54:10.28.2.1]

505.3.2 Unlisted water heaters shall be installed with aclearance of twelve (12) inches (300 mm) on all sidesand rear. Combustible floors under unlisted water heatersshall be protected in an approved manner. [NFPA54:10.28.2.2]

505.4 Pressure-Limiting Devices. A water heater installa-tion shall be provided with overpressure protection by meansof an approved, listed device, installed in accordance with theterms of its listing and the manufacturer's instructions. [NFPA54:10.28.3]505.5 Temperature-Limiting Devices. A water heater in-stallation or a hot water storage vessel installation shall beprovided with over temperature protection by means of an ap-proved, listed device installed in accordance with the terms ofits listing and the manufacturer's instructions. [NFPA54:10.28.4]505.6 Temperature, Pressure, and VacuumRelief Devices.The installation of temperature, pressure, and vacuum reliefdevices or combinations thereof, and automatic gas shutoffdevices, shall be installed in accordance with the terms oftheir listings and the manufacturer’s instructions. A shutoffvalve shall not be placed between the relief valve and thewater heater or on discharge pipes between such valves andthe atmosphere. The hourly Btu discharge capacity or therated steam relief capacity of the device shall be not less thanthe input rating of the water heater. [NFPA 54:10.28.5]

506.0 Oil-Burning and OtherWater Heaters.506.1Water heaters deriving heat from fuels or types of energyother than gas shall be constructed and installed in accordancewith approved standards. Vents or chimneys for such appli-ances shall be approved types. An adequate supply of air forcombustion and for adequate ventilation of heater rooms orcompartments shall be provided. Each such appliance shall beinstalled in a location approved by the Authority Having Ju-risdiction and local and state fire-prevention agencies.506.2 Storage-type water heaters and hot water boilers de-riving heat from fuels or types of energy other than gas, shallbe provided with, in addition to the primary temperature con-trols, an over temperature safety protection device con-structed, listed, and installed in accordance with nationallyrecognized applicable standards for such devices and a com-bination temperature and pressure-relief valve.506.3 Oil-fired water heaters shall be installed in accordancewith NFPA 31, Standard for the Installation of Oil-BurningEquipment.506.4 Indirect-Fired Water Heaters.

506.4.1 Indirect-fired water heaters shall conform to ap-plicable sections of the ASME Boiler and Pressure Ves-sel Code, or to one (1) of the other applicable standardsshown in Table 14-1. Each water heater shall bear a labelin accordance withASME requirements, or an approvedtesting agency, certifying and attesting that such an ap-pliance has been tested, inspected and meets the require-ments of the applicable standards or code.


WATER HEATERS

506.4.2 Indirect-fired water heater that incorporate a sin-gle-wall heat exchanger shall meet all of the followingrequirements:

(1) Connected to a low-pressure hot water boiler lim-ited to a maximum of thirty (30) psig by an approvedsafety or relief valve.

(2) Heater transfer medium is either potable water orcontains fluids having a toxicity rating or Class of 1.

(3) Bear a label with the word “Caution,” followed bythe following statements:

(a) The heat-transfer medium must be water orother nontoxic fluid having a toxic rating orClass of 1 as listed in Clinical Toxicology ofCommercial Products, 5th edition.

(b) The pressure of the heat-transfer medium mustbe limited to a maximum of thirty (30) psig(207 kPa) by an approved safety or relief valve.

Note: The word “Caution” and the statementsin letters having an uppercase height of not lessthan 0.120 of an inch (3.0 mm). The verticalspacing between lines of type shall be not lessthan 0.046 of an inch (1.2 mm). Lowercase let-ters shall be compatible with the uppercase let-ter size specification.

507.0 Air for Combustion and Ventilation.

507.1 General.

507.1.1 Air for combustion, ventilation, and dilution offlue gases for gas utilization appliances installed in build-ings shall be obtained by application of one (1) of themethods covered in Sections 507.2.1 through 507.7. Gasutilization appliances of other than natural draft and Cat-egory I vented appliances shall be provided with com-bustion, ventilation, and dilution air in accordance withthe appliance manufacturer's instructions. Where infil-tration does not provide the necessary air, outdoor airshall be introduced in accordance with methods coveredin Sections 507.4 through 507.7. [NFPA 54:9.3.1.1]

Exceptions:

(1) This provision shall not apply to direct-vent appli-ances.

(2) Type 1 clothes dryers that are provided with make-up air in accordance with section NFPA 54:10.4.3.

507.1.1.1 Clothes Dryer. A device used to dry wetlaundry by means of heat derived from the combus-tion of fuel gases. [NFPA 54:3.3.18]

507.1.1.2 Clothes Dryer, Type 1. Primarily used infamily living environment. May or may not be coin-operated for public use. [NFPA 54:3.3.18.1]

507.1.1.3 Exhausting to the Outdoors. Type 1 andType 2 clothes dryers shall be exhausted to the out-side air. [NFPA 54:10.4.2]

507.1.1.4 Provisions for Make-Up Air. Make-upair shall be provided for Type 1 clothes dryers in ac-cordance with the manufacturer’s installation in-structions. [NFPA 54:10.4.3.1]

507.1.2 Gas appliances of other than natural draft designand other than Category I vented appliances shall be pro-vided with combustion, ventilation, and dilution air inaccordance with the appliance manufacturer's instruc-tions. [NFPA 54:9.3.1.2]

507.1.3 Where used, a draft hood or a barometric draftregulator shall be installed in the same room or enclo-sure as the appliance served so as to prevent any differ-ence in pressure between the hood or regulator and thecombustion air supply. [NFPA 54:9.3.1.4]

507.1.4 Makeup air requirements for the operation of ex-haust fans, kitchen ventilation systems, clothes dryers,and fireplaces shall be considered in determining the ad-equacy of a space to provide combustion air require-ments. [NFPA 54:9.3.1.5]

507.2 Indoor Combustion Air. The required volume of in-door air shall be determined in accordance with Sections507.2.1 or 507.2.2 except that where the air infiltration rate isknown to be less than 0.40 ACH, Section 507.2.2 shall beused. The total required volume shall be the sum of the re-quired volume calculated for all appliances located within thespace. Rooms communicating directly with the space inwhich the appliances are installed through openings not fur-nished with doors, and through combustion air openings sizedand located in accordance with Section 507.3 are considereda part of the required volume. [NFPA 54:9.3.2]

507.2.1 Standard Method. The required volume shallbe not less than fifty (50) cubic feet per 1,000 Btu/hour(4.8 m3/kW). [NFPA 54:9.3.2.1]

507.2.2 Known Air Infiltration Rate Method. Wherethe air infiltration rate of a structure is known, the mini-mum required volume shall be determined as follows[NFPA 54:9.3.2.2]:

(1) For appliances having other than fan-assisted, com-bustion systems: calculate using Equation 5-1 butnot less than thirty-five (35) cubic feet per 1,000Btu/hour (3.4 m3/kW). [NFPA 54:9.3.2.2(1)]

(2) For fan-assisted combustion system appliances, cal-culate using Equation 5-2 but not less than twenty-five (25) cubic feet per 1,000 Btu/hour (2.4 m3/kW).[NFPA 54: 9.3.2.2(2)]

(3) For purposes of this calculation, an infiltration rategreater than 0.60 ACH shall not be used in the equa-tions. [NFPA 54:9.3.2.2(3)]

Equation 5-1:

Required volume other > ( 21 ft3 /ACH) x ( Iother/1,000Btu/h)

Equation 5-2:

Required volume fan > ( 15 ft3 /ACH) x ( Ifan/1,000Btu/h)

Where:

Iother = All appliances other than fan-assisted input inBtu/hour

Ifan = Fan-assisted appliance input in Btu/hour

ACH = Air change per hour (Percent of volume of spaceexchanged per hour, expressed as a decimal)


WATER HEATERS

507.3 Indoor Opening Size and Location. Openings usedto connect indoor spaces shall be sized and located in accor-dance with the following [NFPA 54:9.3.2.3]:

(1) Combining spaces on the same story. Each opening shallhave a free area of not less than one (1) square inch/1,000 Btu/h (2,200 mm2/kW) of the total input rating ofall gas utilization appliances in the space, but not lessthan one-hundred (100) square inches (0.06 m2). One (1)opening shall commence within twelve (12) inches (300mm) of the top, and one (1) opening shall commencewithin twelve (12) inches (300 mm) of the bottom of theenclosure [see Figure 5-7]. The dimension of air open-ings shall be not less than three (3) inches (80 mm).[NFPA 54:9.3.2.3(1)]

(2) Combining spaces in different stories. The volumes ofspaces in different stories shall be considered as com-municating spaces where such spaces are connected byone (1) or more openings in doors or floors having a totalfree area of not less than two (2) square inches/1,000Btu/h (4,400 mm2/kW) of total input rating of all gas uti-lization appliances. [NFPA 54:9.3.2.3(2)]

507.4 Outdoor Combustion Air. Outdoor combustion airshall be provided through opening(s) to the outdoors in ac-cordance with methods Sections 507.4.1 or 507.4.2. The di-mension of air openings shall be not less than three (3) inches(80 mm). [NFPA 54:9.3.3]

507.4.1 Two Permanent Openings Method. Two (2)permanent openings, one (1) commencing within twelve(12) inches (300 mm) of the top and one (1) commenc-ing within twelve (12) inches (300 mm) of the bottom ofthe enclosure shall be provided. The openings shall com-municate directly, or by ducts, with the outdoors orspaces that freely communicate with the outdoors as fol-lows [NFPA 54:9.3.3.1]:

(1) Where directly communicating with the outdoors orwhere communicating to the outdoors through ver-tical ducts, each opening shall have a free area of notless than one (1) square inch/4000 Btu/h (550mm2/kW) of total input rating of all appliances inthe enclosure. [See Figures 5-8 and 5-9.] [NFPA54:9.3.3.1(1)]

(2) Where communicating with the outdoors throughhorizontal ducts, each opening shall have a free areaof not less than one (1) square inch/2,000 Btu/h(1,100 mm2/kW) of total input rating of all appli-ances in the enclosure. [See Figure 5-10] [NFPA54:9.3.3.1(2)]

507.4.2 One Permanent Opening Method. One (1) per-manent opening, commencing within twelve (12) inches(300 mm) of the top of the enclosure, shall be provided.The appliance shall have clearances of not less than one(1) inch (25 mm) from the sides and back and six (6)inches (160 mm) from the front of the appliance. Theopening shall directly communicate with the outdoors orshall communicate through a vertical or horizontal duct tothe outdoors or spaces that freely communicate with the

outdoors [see Figure 5-11] and shall have a minimum freearea of the following [NFPA 54:9.3.3.2]:

(1) One (1) square inch/3,000 Btu/h (700 mm2/kW) ofthe total input rating of all appliances located in theenclosure, and [NFPA 54:9.3.3.2(1)]

(2) Not less than the sum of the areas of all vent con-nectors in the space. [NFPA 54:9.3.3.2(2)]

507.5 Combination Indoor and Outdoor Combustion Air.The use of a combination of indoor and outdoor combustionair shall be in accordance with Sections 507.5.1, 507.5.2 and507.5.3 [see example calculation in NFPA 54 Annex J andthis chapter – Part II] [NFPA 54:9.3.4].

507.5.1 Indoor Openings. Where used, openings con-necting the interior spaces shall comply with Section507.3. [NFPA 54:9.3.4(1)]

507.5.2 Outdoor openings shall be located in accordancewith Sections 507.4.1 or 507.4.2. [NFPA 54:9.3.4(2)]

507.5.3 Outdoor Openings Size. The outdoor openingssize shall be calculated in accordance with the following[NFPA 54:9.3.4(3)]:

(1) The ratio of interior spaces shall be the available vol-ume of communicating spaces divided by the re-quired volume.

(2) The outdoor size reduction factor shall be one (1)minus the ratio of interior spaces.

(3) The minimum size of outdoor openings shall be thefull size of outdoor openings calculated in accor-dance with Sections 507.4.1 or 507.4.2, multipliedby the reduction factor. The dimension of air open-ings shall be not less than three (3) inches (80 mm).[NFPA 54:9.3.4(3)(c)]

507.6 Engineered Installations. Engineered combustion airinstallations shall provide an adequate supply of combustion,ventilation, and dilution air and shall be approved by the Au-thority Having Jurisdiction. [NFPA 54:9.3.5]

507.7 Mechanical Combustion Air Supply. Where com-bustion air is provided by a mechanical air supply system, thecombustion air shall be supplied from outdoors at the mini-mum rate of 0.35 cubic feet/min per 1,000 Btu/h (0.034m3/min per kW) for appliances located within the space.[NFPA 54:9.3.6]

507.7.1 Where exhaust fans are installed, additional airshall be provided to replace the exhausted air. [NFPA54:9.3.6.1]

507.7.2 Each of the appliances served shall be inter-locked to the mechanical air supply system to preventmain burner operation where the mechanical air supplysystem is not in operation. [NFPA 54:9.3.6.2]

507.7.3 Where combustion air is provided by the build-ing's mechanical ventilation system, the system shall pro-vide the specified combustion air rate in addition to therequired ventilation air. [NFPA 54:9.3.6.3]

507.8 Louvers, Grilles and Screens.

(A) Louvers and Grilles. The required size of openings forcombustion, ventilation, and dilution air shall be based


WATER HEATERS

<on the net free area of each opening. Where the free areathrough a design of louver or grille is known, it shall beused in calculating the size opening required to providethe free area specified. Where the design and free areaare not known, it shall be assumed that wood louvers willhave 25 percent free area and metal louvers and grilleswill have 75 percent free area. Nonmotorized louvers andgrilles shall be fixed in the open position. [NFPA54:9.3.7.1]

(B) Minimum Screen Mesh Size. Screens shall be not lessthan one-fourth (1⁄4) inch mesh. [NFPA 54:9.3.7.2]

(C) Motorized louvers shall be interlocked with the appli-ance so they are proven in the full open position prior tomain burner ignition and during main burner operation.Means shall be provided to prevent the main burner fromigniting should the louver fail to open during burner start-up and to shut down the main burner if the louvers closeduring burner operation. [NFPA 54:9.3.7.3]

507.9 Combustion Air Ducts. Combustion air ducts shallcomply with the following:(1) Ducts shall be of galvanized steel or a material having

equivalent corrosion resistance, strength, and rigidity.[NFPA 54:9.3.8.1]Exception:Within dwelling units, unobstructed stud andjoist spaces shall not be prohibited from conveying com-bustion air, provided that not more than one (1) fireblockis removed.

(2) Ducts shall terminate in an unobstructed space, allowingfree movement of combustion air to the appliances.[NFPA 54:9.3.8.2]

(3) Ducts shall serve a single space. [NFPA 54:9.3.8.3](4) Ducts shall not service both upper and lower combustion

air openings where both such openings are used. The sep-aration between ducts serving upper and lower combus-tion air openings shall be maintained to the source ofcombustion air. [NFPA 54:9.3.8.4]

(5) Ducts shall not be screened where terminating in an atticspace. [NFPA 54:9.3.8.5]

(6) Intakes for combustion air ducts located exterior to thebuilding shall have the lowest side of the combustion airintake openings located at least twelve (12) inches (300mm) vertically from the adjoining finished grade level.

(7) Horizontal upper combustion air ducts shall not slopedownward toward the source of combustion air. [NFPA54:9.3.8.6]

(8) The remaining space surrounding a chimney liner, gasvent, special gas vent, or plastic piping installed within amasonry chimney flue, metal or factory-built chimney,shall not be used to supply combustion air [NFPA54:9.3.8.7], unless it is listed and shown in the manufac-turer's installation instructions.

508.0 OtherWater Heater Installation Requirements.508.1 The Authority Having Jurisdiction shall have the au-thority to require the use of an approved dielectric insulator

on the water piping connections of water heaters and relatedwater heating appliances.508.2 Protection from Seismic Damage.Water heaters shallbe anchored or strapped to resist horizontal displacement dueto earthquake motion. Strapping shall be at points within theupper one third (1⁄3) and lower one-third (1⁄3) of its vertical di-mensions. At the lower point, a minimum distance of four (4)inches (102 mm) shall be maintained above the controls withthe strapping.Note: [HCD 1 & HCD 2] Reference Health and Safety CodeSection 19211(a) which addresses new, replacement, and ex-isting water heaters.Note: The applicable subsection of Health and Safety CodeSection 19211(a) which addresses new, replacement, and ex-isting water heaters is repeated here for clarity and reads asfollows:

Section 19211(a) Notwithstanding Section 19100, all newand replacement water heaters, and all existing residentialwater heaters shall be braced, anchored, or strapped to resistfalling or horizontal displacement due to earthquake motion.At a minimum, any water heater shall be secured in accor-dance with the California Plumbing Code, or modificationsmade thereto by a city, county, or city and county pursuant toSection 17958.5.508.3Awater heater supported from the ground shall rest onlevel concrete or other approved base extending not less thanthree (3) inches (76 mm) above the adjoining ground level.508.4When a water heater is located in an attic, attic-ceilingassembly, floor-ceiling assembly, or floor-subfloor assemblywhere damage results from a leaking water heater, a water-tight pan of corrosion-resistant materials shall be installed be-neath the water heater with not less than three-quarters (3⁄4) ofan inch (20 mm) diameter drain to an approved location.508.5 Relief Valve Discharge. Discharge from a relief valveinto a water heater pan shall be prohibited.508.6Added or ConvertedAppliances.When an additionalor replacement appliance is installed or an appliance is con-verted to gas from another fuel, the location in which the ap-pliance is to be operated shall be checked to verify thefollowing [NFPA 54:9.1.2]:

508.6.1 Air for combustion and ventilation is providedwhere required, in accordance with the provisions of Sec-tion 507.0. Where existing facilities are not adequate,they shall be upgraded to Section 507.0 specifications.[NFPA 54:9.1.2(1)]508.6.2 The installation components and appliances meetthe clearances to combustible material provisions ofNFPA54:9.2.2. It shall be determined that the installationand operation of the additional or replacement appliancedoes not render the remaining appliance unsafe for con-tinued operation. [NFPA 54:9.1.2(2)](The following reference was extracted from NFPA 54,National Fuel Gas Code).9.2.2 Clearance to Combustible Materials. Appliancesand their vent connectors shall be installed with clear-ances from combustible material so their operation will


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not create a hazard to persons or property. Minimumclearances between combustible walls and the back andsides of various conventional types of appliances andtheir vent connectors are specified in Chapters 10 and12. (Reference can also be made to NFPA 211, Standardfor Chimneys, Fireplaces, Vents, and Solid Fuel-BurningAppliances.)508.6.3 The venting system is constructed and sized inaccordance with the provisions of this chapter. Where theexisting venting system is not adequate, it shall be up-graded to comply with this chapter. [NFPA 54:9.1.2(3)]

508.7 Types of Gases. It shall be determined whether the gas-utilization appliance has been designed for use with the gas towhich it will be connected. No attempt shall be made to con-vert the appliance from the gas specified on the rating platefor use with a different gas without consulting the installationinstructions, the serving gas supplier, or the appliance manu-facturer for complete instructions. [NFPA 54:9.1.3]508.8 Safety Shutoff Devices for Unlisted LP-Gas Appli-ance Used Indoors. Unlisted gas utilization appliances foruse with undiluted liquefied petroleum gases and installed in-doors shall be equipped with safety shutoff devices of thecomplete shutoff type. [NFPA 54:9.1.4]508.9 Use of Air or Oxygen Under Pressure.Where air oroxygen under pressure is used in connection with the gas sup-ply, effective means such as a back-pressure regulator and re-lief valve shall be provided to prevent air or oxygen frompassing back into the gas piping. Where oxygen is used, in-stallation shall be in accordance with NFPA 51, Standard forthe Design and Installation of Oxygen-Fuel Gas Systems forWelding, Cutting, and Allied Processes. [NFPA 54:9.1.5]508.10 Protection of GasAppliances from Fumes or GasesOther than Products of Combustion. Non-direct vent-typegas appliances installed in beauty shops, barbershops, or otherfacilities where chemicals that generate corrosive or flam-mable products such as aerosol sprays are routinely used shallbe located in an equipment room separate or partitioned offfrom other areas with provisions for combustion and dilutionair from outdoors. Direct vent appliances shall be installed inaccordance with the appliance manufacturer's installation in-structions. [NFPA 54:9.1.6.2]508.11 Process Air. In addition to air needed for combustionin commercial or industrial processes, process air shall be pro-vided as required for cooling of equipment or material, con-trolling dew point, heating, drying, oxidation, dilution, safetyexhaust, odor control, air for compressors, and for comfortand proper working conditions for personnel. [NFPA54:9.1.7]508.12 Building Structural Members.

508.12.1 Structural members of a building shall not passthrough gas utilization appliances having an operatingtemperature exceeding 500°F (260°C). [NFPA54:9.1.8.1]508.12.2 Structural members passing through gas uti-lization appliances having an operating temperature of500°F (260°C) or less shall be of noncombustible mate-rial. Building columns, girders, beams, or trusses shall

not be installed within appliances, unless insulation andventilation are provided to avoid deterioration in strengthand linear expansion of the building structure in either avertical or a horizontal direction. [NFPA 54:9.1.8.2]508.12.3Gas utilization appliances shall be furnished ei-ther with load-distributing bases or with a sufficient num-ber of supports to prevent damage to either the buildingstructure or appliance. [NFPA 54:9.1.8.3]508.12.4 At the locations selected for installation of thegas utilization appliance, the dynamic and static load-carrying capacities of the building structure shall bechecked to determine whether they are adequate to carrythe additional loads. The appliance shall be supportedand shall be connected to the piping so as not to exertundue stress on the connections. [NFPA 54:9.1.8.4]

508.13 Flammable Vapors. Gas appliances shall not be in-stalled in areas where the open use, handling, or dispensing offlammable liquids occurs, unless the design, operation, or in-stallation reduces the potential of ignition of the flammablevapors. Gas utilization appliances installed in compliancewith Sections 508.14, 508.15, or 508.16 shall be consideredto comply with the intent of this provision. [NFPA 54:9.1.9]508.14 Installation in Residential Garages.(1) Gas utilization appliances in residential garages and in

adjacent spaces that open to the garage and are not partof the living space of a dwelling unit shall be installedso that burners and burner-ignition devices are locatednot less than eighteen (18) inches (450 mm) above thefloor unless listed as flammable vapor ignition resistant.[NFPA 54:9.1.10.1]

(2) Such appliances shall be located or protected so it is notsubject to physical damage by a moving vehicle. [NFPA54:9.1.10.2]

(3) When appliances are installed in a separate enclosedspace having access only from outside of the garage,such appliances shall be permitted to be installed at floorlevel, providing the required combustion air is takenfrom the exterior of the garage. [NFPA 54:9.1.10.3]

508.15 Installation in Commercial Garages.508.15.1 Parking Structures.Gas utilization appliancesinstalled in enclosed, basement, and underground park-ing structures shall be installed in accordance withNFPA 88A, Standard for Parking Structures. [NFPA54:9.1.11.1]508.15.2 Repair Garages.Gas utilization appliances in-stalled in repair garages shall be installed in a detachedbuilding or room, separated from repair areas by wallsor partitions, floors, or floor-ceiling assemblies that areconstructed so as to prohibit the transmission of vaporsand having a fire-resistance rating of not less than one(1) hour, and that have no openings in the wall separat-ing the repair area within eight (8) feet (2.5 m) of thefloor. Wall penetrations shall be fire-stopped. Air forcombustion purposes shall be obtained from outside thebuilding. The heating room shall not be used for the stor-age of combustible materials. [NFPA 54:9.1.11.2]


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Exceptions:(1) Overhead heaters where installed not less than eight

(8) ft (2.5 m) above the floor shall be permitted.(2) Heating appliances for vehicle repair areas where

there is no dispensing or transferring of Class I orClass II flammable or combustible liquids or lique-fied petroleum gas shall be installed in accordancewith NFPA 30A, Code for Motor Fuel DispensingFacilities and Repair Garages. [NFPA 54:9.1.11.2]

508.16 Installation inAircraft Hangars. Heaters in aircrafthangars shall be installed in accordance with NFPA409, Stan-dard on Aircraft Hangars. [NFPA 54:9.1.12]508.17 GasAppliance Physical Protection.Where it is nec-essary to locate gas utilization appliances close to a passage-way traveled by vehicles or equipment, guardrails or bumperplates shall be installed to protect the appliance from dam-age. [NFPA 54:9.1.13]508.18 Venting of Flue Gases.Gas utilization appliances shallbe vented in accordance with the provisions of this chapter andNFPA 54, National Fuel Gas Code, Chapter 12. [NFPA54:9.1.14]508.19 Extra Device or Attachment. No device or attach-ment shall be installed on any gas utilization appliance thatcould in any way impair the combustion of gas. [NFPA54:9.1.15]508.20 Adequate Capacity of Piping.When additional gasutilization appliances are being connected to a gas piping sys-tem, the existing piping shall be checked to determine if ithas adequate capacity (See Section 1209.4.3). Where inade-quate, the existing system shall be enlarged as necessary, orseparate gas piping of adequate capacity shall be run from thepoint of delivery to the appliance. [NFPA 54:9.1.16]508.21 Avoiding Strain on Gas Piping. Gas utilization ap-pliances shall be supported and so connected to the piping asnot to exert undue strain on the connections. [NFPA54:9.1.17]508.22 GasAppliance Pressure Regulators.Where the gassupply pressure exceeds that at which the gas utilization ap-pliance is designed to operate or varies beyond the designpressure limits of the appliance, a gas appliance pressure reg-ulator shall be installed. [NFPA 54:9.1.18]508.23 Venting of Gas Appliance Pressure Regulators.Venting of gas appliance pressure regulators shall complywith the following requirements [NFPA 54:9.1.19]:

508.23.1Gas appliance pressure regulators requiring ac-cess to the atmosphere for successful operation shall beequipped with vent piping leading outdoors or, if the reg-ulator vent is an integral part of the appliance, into thecombustion chamber adjacent to a continuous pilot, un-less constructed or equipped with a vent limiting meansto limit the escape of gas from the vent opening in theevent of diaphragm failure. [NFPA 54:9.1.19(1)]508.23.2 Vent limiting means shall be employed on listedgas appliance pressure regulators only. [NFPA54:9.1.19(2)]508.23.3 In the case of vents leading outdoors, meansshall be employed to prevent water from entering this

piping and also to prevent blockage of vents by insectsand foreign matter. [NFPA 54:9.1.19(3)]508.23.4 Under no circumstances shall a regulator bevented to the gas utilization appliance flue or exhaustsystem. [NFPA 54:9.1.19(4)]508.23.5 In the case of vents entering the combustionchamber, the vent shall be located so the escaping gaswill be readily ignited by the pilot and the heat liberatedthereby will not adversely affect the normal operation ofthe safety shutoff system. The terminus of the vent shallbe securely held in a fixed position relative to the pilot.For manufactured gas, the need for a flame arrester in thevent piping shall be determined. [NFPA 54:9.1.19(5)]508.23.6 Vent lines from a gas appliance pressure regu-lator and bleed lines from a diaphragm-type valve shallnot be connected to a common manifold terminating in acombustion chamber. Vent lines shall not terminate inpositive-pressure-type combustion chambers. [NFPA54:9.1.19(6)]

508.24 Bleed Lines for Diaphragm-Type Valves. Bleedlines shall comply with the following requirements [NFPA54:9.1.20]:

508.24.1 Diaphragm-type valves shall be equipped toconvey bleed gas to the outside atmosphere or into thecombustion chamber adjacent to a continuous pilot.[NFPA 54:9.1.20(1)]508.24.2 In the case of bleed lines leading outdoors,means shall be employed to prevent water from enteringthis piping and also to prevent blockage of vents by in-sects and foreign matter. [NFPA 54:9.1.20(2)]508.24.3Bleed lines shall not terminate in the gas utilizationappliance flue or exhaust system. [NFPA54:9.1.20(3)]508.24.4 In the case of bleed lines entering the combus-tion chamber, the bleed line shall be located so the bleedgas will be readily ignited by the pilot and the heat lib-erated thereby will not adversely affect the normal oper-ation of the safety shutoff system. The terminus of thebleed line shall be securely held in a fixed position rela-tive to the pilot. For manufactured gas, the need for aflame arrester in the bleed line piping shall be deter-mined. [NFPA 54:9.1.20(4)]508.24.5 Bleed lines from a diaphragm-type valve andvent lines from a gas appliance pressure regulator shallnot be connected to a common manifold terminating in acombustion chamber. Bleed lines shall not terminate inpositive-pressure-type combustion chambers. [NFPA54:9.1.20(5)]

508.25 Combination ofAppliances.Any combination of gasutilization appliances, attachments, or devices used togetherin any manner shall comply with the standards that apply tothe individual appliance. [NFPA 54:9.1.21]508.26 Installation Instructions. The installing agency shallconform with the appliance manufacturer's recommendations


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in completing an installation. The installing agency shall leavethe manufacturer's installation, operating, and maintenance in-structions in a location on the premises where they will be read-ily available for reference and guidance for the AuthorityHaving Jurisdiction, service personnel, and the owner or oper-ator. [NFPA54:9.1.22]508.27 Protection of Outdoor Appliances. Gas utilizationappliances not listed for outdoor installation but installed out-doors shall be provided with protection to the degree that theenvironment requires. Appliances listed for outdoor installa-tion shall be permitted to be installed without protection inaccordance with the provisions of its listing (See NFPA54:9.2.1). [NFPA 54:9.1.23]

(The following references were extracted from NFPA 54,National Fuel Gas Code.)9.2 Accessibility and Clearance.9.2.1 Accessibility for Service. Gas utilization appliancesshall be located with respect to building construction andother equipment so as to permit access to the gas utiliza-tion appliance. Sufficient clearance shall be maintained topermit cleaning of heating surfaces; the replacement offilters, blowers, motors, burners, controls, and vent con-nections; the lubrication of moving parts where neces-sary; the adjustment and cleaning of burners and pilots;and the proper functioning of explosion vents, if provided.For attic installation, the passageway and servicing areaadjacent to the appliance shall be floored.

509.0 Appliances on Roofs.509.1 General.(1) Gas utilization appliances on roofs shall be designed or

enclosed so as to withstand climactic conditions in thearea in which they are installed. Where enclosures areprovided, each enclosure shall permit easy entry andmovement, shall be of reasonable height, and shall havenot less than a thirty (30) inch (760 mm) clearance be-tween the entire service access panel(s) of the applianceand the wall of the enclosure. [NFPA 54:9.4.1.1]

(2) Roofs on which an appliance is to be installed shall be ca-pable of supporting the additional load or shall be rein-forced to support the additional load. [NFPA 54:9.4.1.2]

(3) All access locks, screws, and bolts shall be of corrosion-resistant material. [NFPA 54:9.4.1.3]

509.2 Installation of Appliances on Roofs.(1) Gas utilization appliances shall be installed in accordance

with its listing and the manufacturer's installation in-structions. [NFPA 54:9.4.2.1]

(2) Appliances shall be installed on a well-drained surfaceof the roof. Not less than six (6) feet (1.8 m) of clearanceshall be available between any part of the appliance andthe edge of a roof or similar hazard, or rigidly fixed rails,guards, parapets, or other building structures not less thanforty-two (42) inches (1.1 m) in height shall be providedon the exposed side. [NFPA 54:9.4.2.2]

(3) Appliances requiring an external source of electricalpower for its operation shall be provided with (1) a read-ily accessible electrical disconnecting means within sightof the appliance that will completely de-energize the ap-pliance, and (2) a 120-VAC grounding-type receptacleoutlet on the roof adjacent to the appliance. The recepta-cle outlet shall be on the supply side of the disconnectswitch. [NFPA 54:9.4.2.3]

(4) Where water stands on the roof of the appliance or in thepassageways to the appliance, or where the roof is of a de-sign having a water seal, a suitable platform, walkway, orboth shall be provided above the waterline. Such platformsor walkways shall be located adjacent to the appliance andcontrol panels so that the appliance can be safely servicedwhere water stands on the roof. [NFPA 54:9.4.2.4]

509.3 Access to Appliances on Roofs.509.3.1 Gas utilization appliances located on roofs orother elevated locations shall be accessible. [NFPA54:9.4.3.1]509.3.2 Buildings exceeding fifteen (15) feet (4.6 m) inheight shall have an inside means of access to the roof,unless other means acceptable to the Authority HavingJurisdiction are used. [NFPA 54:9.4.3.2]509.3.3 The inside means of access shall be a permanent,or fold-away inside stairway or ladder, terminating in anenclosure, scuttle, or trap door. Such scuttles or trap doorsshall be not less than twenty-two (22) inches x twenty-four (24) inches (560 mm x 610 mm) in size, shall openeasily and safely under all conditions, especially snow;and shall be constructed so as to permit access from theroof side unless deliberately locked on the inside.

Not less than six (6) feet (1.8 m) of clearance shallbe available between the access opening and the edge ofthe roof or similar hazard, or rigidly fixed rails or guardsnot less than forty-two (42) inches (1.1 m) in height shallbe provided on the exposed side.Where parapets or otherbuilding structures are utilized in lieu of guards or rails,they shall be not less than forty-two (42) inches (1.1 m)in height. [NFPA 54:9.4.3.3]509.3.4 Permanent lighting shall be provided at the roofaccess. The switch for such lighting shall be located in-side the building near the access means leading to theroof. [NFPA 54:9.4.3.4]

509.4 Appliances in Attics.509.4.1 Attic Access. An attic in which an appliance isinstalled shall be accessible through an opening and pas-sageway not less than as large as the largest component ofthe appliance, and not less than twenty-two (22) inches xthirty (30) inches (560 mm x 760 mm). [NFPA 54:9.5.1]509.4.2Where the height of the passageway is less thansix (6) feet (1.8 m), the distance from the passageway ac-cess to the appliance shall not exceed twenty (20) feet(6.1 m) measured along the centerline of the passageway.[NFPA 54:9.5.1.1]


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509.4.3 The passageway shall be unobstructed and shallhave solid flooring not less than twenty-four (24) inches(610 mm) wide from the entrance opening to the appli-ance. [NFPA 54:9.5.1.2]509.4.4 Work Platform. A level working platform notless than thirty (30) inches (760 mm) by thirty (30)inches (760 mm) shall be provided in front of the serviceside of the appliance. [NFPA 54:9.5.2]509.4.5 Lighting and Convenience Outlet. A perma-nent 120-volt receptacle outlet and a lighting fixture shallbe installed near the appliance. The switch controllingthe lighting fixture shall be located at the entrance to thepassageway. [NFPA 54:9.5.3]

510.0 Venting of Appliances.510.1 General. This section recognizes that the choice ofventing materials and the methods of installation of ventingsystems are dependent on the operating characteristics of theappliance. [NFPA 54:12.2.1]

510.1.1 Categories.The operating characteristics of ventedgas utilization appliances can be categorizedwith respect to(1) positive or negative pressure within the venting system,and (2) whether or not the appliance generates flue or ventgases that can condense in the venting system. See NFPA54, National Fuel Gas Code, Section 3.3 for the definitionof these vented appliance categories. [NFPA54:12.2.2]510.1.2 Installation. Listed vents shall be installed in ac-cordance with Chapter 5 and the manufacturer’s instal-lation instructions. [NFPA 54:12.2.3]510.1.3 Appliance vents shall not discharge into anyspace enclosed by screens having openings less than one-fourth (1⁄4) inch (6.4 mm) mesh.

510.2 Specification for Venting.510.2.1 Connection to Venting Systems. Except as per-mitted in Sections 510.2.2 through 510.2.6, gas utiliza-tion appliances shall be connected to venting systems.[NFPA 54:12.3.1]510.2.2 Appliances Not Required to Be Vented. Thefollowing appliances shall not be required to be vented[NFPA 54:12.3.2]:

510.2.2.1 Listed ranges. [NFPA 54:12.3.2(1)]510.2.2.2 Built-in domestic cooking units listed andmarked for optional venting. [NFPA 54:12.3.2(2)]510.2.2.3 Listed hot plates and listed laundry stoves.[NFPA 54:12.3.2(3)]510.2.2.4 Listed Type 1 clothes dryers shall be ex-hausted to the outside air. [NFPA 54:12.3.2(4)]510.2.2.5Asingle listed booster-type (automatic in-stantaneous) water heater, when designed and usedsolely for the sanitizing rinse requirements of a dish-washing machine, provided that the appliance is in-stalled with the draft hood in place and unaltered if

a draft hood is required, in a commercial kitchenhaving a mechanical exhaust system; where installedin this manner, the draft hood outlet shall be not lessthan thirty-six (36) inches (910 mm) vertically andsix (6) inches (150 mm) horizontally from any sur-face other than the appliance. [NFPA 54:12.3.2(5)]510.2.2.6 Listed refrigerators. [NFPA 54:12.3.2(6)]510.2.2.7 Counter appliances. [NFPA 54:12.3.2(7)]510.2.2.8 Direct gas-fired makeup air heaters.[NFPA 54:12.3.2(9)]510.2.2.9Other appliances listed for unvented use andnot provided with flue collars. [NFPA54:12.3.2(10)]510.2.2.10 Specialized appliance of limited inputsuch as laboratory burners or gas lights. [NFPA54:12.3.2(11)]

Where appliances in Sections 510.2.2.5 through510.2.2.10 are installed so the aggregate input ratingexceeds 20 Btu/h/ft.3 (207W/m3) of room or space inwhich it is installed, one (1) or more shall be pro-vided with venting systems or other approved meansfor removing the vent gases to the outside atmos-phere so the aggregate input rating of the remainingunvented appliance does not exceed 20 Btu/h/ft.3(207W/m3). Where the calculation includes the vol-ume of an adjacent room or space, the room or spacein which the appliance is installed shall be directlyconnected to the adjacent room or space by a door-way, archway, or other opening of comparable sizethat cannot be closed. [NFPA 54:12.3.2]

510.2.3 Ventilating Hoods. Ventilating hoods and ex-haust systems shall be permitted to be used to vent gasutilization appliances installed in commercial applica-tions (See Section 510.3.5) and to vent industrial appli-ances, particularly where the process itself requires fumedisposal. [NFPA 54:12.3.3]510.2.4 Well-Ventilated Spaces. The operation of in-dustrial appliances such that its flue gases are dischargeddirectly into a large and well-ventilated space shall bepermitted. [NFPA 54:12.3.4]510.2.5 Direct-Vent Appliances. Listed direct-vent gasutilization appliances shall be considered properly ventedwhere installed in accordance with the terms of its listing,the manufacturer's instructions, and Section 510.8.3 of thiscode. [NFPA54:12.3.5]510.2.6Appliances with Integral Vents.Gas utilizationappliances incorporating integral venting means shall beconsidered properly vented where installed in accordancewith its listing, the manufacturer's instructions, and Sec-tions 510.8.1 and 510.8.2 of this code. [NFPA54:12.3.6]

510.3 Design and Construction.510.3.1Minimum Safe Performance.Aventing systemshall be designed and constructed so as to develop a pos-itive flow adequate to remove flue or vent gases to theoutside atmosphere. [NFPA 54:12.1]


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510.3.2Appliance Draft Requirements.Aventing sys-tem shall satisfy the draft requirements of the appliancein accordance with the manufacturer's instructions.[NFPA 54:12.4.1]510.3.3 Design and Construction. Gas utilization ap-pliances required to be vented shall be connected to aventing system designed and installed in accordance withthe provisions of Sections 510.4 through 510.15 of thiscode. [NFPA 54:12.4.2]510.3.4 Mechanical Draft Systems.

510.3.4.1 Mechanical draft systems shall be listedand shall be installed in accordance with the terms oftheir listing and both the appliance and the mechan-ical draft system manufacturer’s instructions. [NFPA54:12.4.3.1]510.3.4.2 Gas utilization appliances requiring vent-ing shall be permitted to be vented by means of me-chanical draft systems of either forced or induceddraft design. [NFPA 54:12.4.3.2]Exception: Incinerators.510.3.4.3 Forced draft systems and portions of in-duced draft systems under positive pressure duringoperation shall be designed and installed so as to pre-vent leakage of flue or vent gases into a building.[NFPA 54:12.4.3.3]510.3.4.4Vent connectors serving appliances ventedby natural draft shall not be connected into any por-tion of mechanical draft systems operating underpositive pressure. [NFPA 54:12.4.3.4]510.3.4.5 Where a mechanical draft system is em-ployed, provision shall be made to prevent the flowof gas to the main burners when the draft system isnot performing so as to satisfy the operating re-quirements of the appliance for safe performance.[NFPA 54:12.4.3.5]510.3.4.6 The exit terminals of mechanical draft sys-tems shall be not less than seven (7) feet (2.1 m)above finished grade where located adjacent to pub-lic walkways and shall be located as specified inSections 510.8.1 and 510.8.2 of this code. [NFPA54:12.4.3.6]

510.3.5 Ventilating Hoods and Exhaust Systems.510.3.5.1 Ventilating hoods and exhaust systemsshall be permitted to be used to vent gas utilizationappliances installed in commercial applications.[NFPA 54:12.4.4.1]510.3.5.2Where automatically operated appliances,other than commercial cooking appliances, arevented through a ventilating hood or exhaust systemequipped with a damper or with a power means ofexhaust, provisions shall be made to allow the flowof gas to the main burners only when the damper isopen to a position to properly vent the appliance andwhen the power means of exhaust is in operation.[NFPA 54:12.4.4.2]

510.3.6 Circulating Air Ducts and Furnace Plenums.Venting systems shall not extend into or pass through anyfabricated air duct or furnace plenum. [NFPA 54-09:12.4.5.1]

510.4 Type of Venting System to Be Used.510.4.1 The type of venting system to be used shall be inaccordance with Table 5-2. [NFPA 54:12.5.1]510.4.2 Plastic Piping. Plastic piping used for ventingappliances listed for use with such venting materials shallbe approved. [NFPA 54:12.5.2]510.4.3 Plastic Vent Joints. Plastic pipe and fittings usedto vent appliances shall be installed in accordance withthe appliance manufacturer’s installation instructions.Where primer is required, it shall be of a contrastingcolor. [NFPA 54-09:12.5.3]510.4.4 Special Gas Vent. Special gas vent shall belisted and installed in accordance with the terms of thespecial gas vent listing and the manufacturer's instruc-tions. [NFPA 54:12.5.3]

510.5 Masonry, Metal, and Factory-Built Chimneys.510.5.1 Listing or Construction.

510.5.1.1 Factory-built chimneys shall be installed inaccordance with their listing and the manufacturer’sinstructions. Factory-built chimneys used to vent ap-pliances that operate at positive vent pressure shall belisted for such application. [NFPA 54:12.6.1.1]510.5.1.2Metal chimneys shall be built and installedin accordance with NFPA 211, Standard for Chim-neys, Fireplaces, Vents, and Solid Fuel-Burning Ap-pliances. [NFPA 54:12.6.1.2]510.5.1.3 Masonry chimneys shall be built and in-stalled in accordance with NFPA 211, Standard forChimneys, Fireplaces, Vents, and Solid Fuel-Burn-ing Appliances, and lined with approved clay fluelining, a listed chimney lining system, or other ap-proved material that will resist corrosion, erosion,softening, or cracking from vent gases at tempera-tures up to 1,800°F (982°C). [NFPA 54:12.6.1.3]Exception: Masonry chimney flues lined with achimney lining system specifically listed for usewith listed gas appliances with draft hoods, Cate-gory I appliances, and other gas appliances listedfor use with Type B vents shall be permitted. Theliner shall be installed in accordance with the linermanufacturer's instructions and the terms of the list-ing. A permanent identifying label shall be attachedat the point where the connection is to be made tothe liner. The label shall read: "This chimney lineris for appliances that burn gas only. Do not connectto solid- or liquid-fuel-burning appliances or incin-erators." [NFPA 54:12.6.1.3]

510.5.2 Termination.510.5.2.1 A chimney for a residential-type or low-heat gas utilization appliance shall extend at leastthree (3) feet (0.9 m) above the highest point whereit passes through the roof of a building and at leasttwo (2) feet (0.6 m) exceeding any portion of a


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building within a horizontal distance of ten (10) feet(3.0 m). [See Figure 5-1.] [NFPA 54:12.6.2.1]

510.5.2.2 A chimney for a medium-heat applianceshall extend at least ten (10) feet (3.0 m) exceedingany portion of any building within twenty-five (25)feet (7.6 m). [NFPA 54:12.6.2.2]

510.5.2.3 A chimney shall extend at least five (5)feet (1.5 m) above the highest connected appliancedraft hood outlet or flue collar. [NFPA 54:12.6.2.3]

510.5.2.4 Decorative shrouds shall not be installed atthe termination of factory-built chimneys exceptwhere such shrouds are listed and labeled for usewith the specific factory-built chimney system andare installed in accordance with manufacturer’s in-stallation instructions. [NFPA 54:12.6.2.4]

510.5.3 Size of Chimneys. The effective area of a chim-ney venting system serving listed gas appliances withdraft hoods, Category I appliances, and other applianceslisted for use with Type B vents shall be in accordancewith one of the following methods [NFPA 54:12.6.3.1]:

(1) This chapter and NFPA 54: Chapter 13. [NFPA54:12.6.3.1(1)]

(2) For sizing an individual chimney venting system fora single appliance with a draft hood, the effectiveareas of the vent connector and chimney flue shallbe not less than the area of the appliance flue collaror draft hood outlet or exceeding seven (7) times thedraft hood outlet area. [NFPA 54:12.6.3.1(2)]

(3) For sizing a chimney venting system connected totwo (2) appliances with draft hoods, the effective areaof the chimney flue shall be not less than the area ofthe larger draft hood outlet plus 50 percent of the areaof the smaller draft hood outlet, or exceeding seven(7) times the smallest draft hood outlet area. [NFPA54:12.6.3.1(3)]

(4) Other approved engineering methods. [NFPA54:12.6.3.1(5)]

(5) Chimney venting systems using mechanical draftshall be sized in accordance with approved engi-neering methods. [NFPA 54:12.6.3.1(4)]

510.5.4 Inspection of Chimneys.

(A) Before replacing an existing appliance or connectinga vent connector to a chimney, the chimney pas-sageway shall be examined to ascertain that it isclear and free of obstructions and shall be cleaned ifpreviously used for venting solid- or liquid-fuel-burning appliances or fireplaces. [NFPA 54:12.6.4.1]

(B) Chimneys shall be lined in accordance with NFPA 211,Standard for Chimneys, Fireplaces, Vents, and Solid-Fuel Burning Appliances. [NFPA 54-09:12.6.4.2]

Exception: Existing chimneys shall be permitted tohave their use continued where an appliance is re-placed by an appliance of similar type, input rating,and efficiency, where the chimney complies with510.5.4, and the sizing of the chimney is in accor-dance with 510.5.3.


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FIGURE 5-1 TYPICAL TERMINATION LOCATIONS FOR

CHIMNEYS AND SINGLE-WALL METAL PIPES SERVING

RESIDENTIAL-TYPE AND LOW-HEAT APPLIANCE

[NFPA 54: FIGURE 12.6.2.1]

(C) Cleanouts shall be examined to determine that theywill remain tightly closed when not in use. [NFPA54:12.6.4.3]

(D) When inspection reveals that an existing chimney isnot safe for the intended application, it shall be re-paired, rebuilt, lined, relined, or replaced with a ventor chimney to conform to NFPA 211, Standard forChimneys, Fireplaces, Vents, and Solid-Fuel-Burn-ing Appliances, and shall be suitable for the appli-ances to be attached. [NFPA 54:12.6.4.4]

510.5.5 Chimney Serving Appliances Burning Other

Fuels.

510.5.5.1 Gas utilization appliances shall not be con-nected to a chimney flue serving a separate appliancedesigned to burn solid fuel. [NFPA 54:12.6.5.1]

510.5.5.2 Where one (1) chimney serves gas uti-lization appliances and liquid fuel-burning appli-ances, the appliance shall be connected throughseparate openings or shall be connected through asingle opening where joined by a suitable fitting lo-cated as close as practical to the chimney. Wheretwo (2) or more openings are provided into one (1)chimney flue, they shall be at different levels. Wherethe gas utilization appliance is automatically con-trolled, it shall be equipped with a safety shutoff de-vice. [NFPA 54:12.6.5.2]


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ROOF PITCH HEIGHTS

ROOF PITCH H(minimum) ft. m

Flat to 6⁄12 1.0 0.30

Over 6⁄12 to 7⁄12 1.25 0.38

Over 7⁄12 to 8⁄12 1.5 0.46

Over 8⁄12 to 9⁄12 2.0 0.61

Over 9⁄12 to 10⁄12 2.5 0.76

Over 10⁄12 to 11⁄12 3.25 0.99

Over 11⁄12 to 12⁄12 4.0 1.22

Over 12⁄12 to 14⁄12 5.0 1.52

Over 14⁄12 to 16⁄12 6.0 1.83

Over 16⁄12 to 18⁄12 7.0 2.13

Over 18⁄12 to 20⁄12 7.5 2.27

Over 20⁄12 to 21⁄12 8.0 2.44

FIGURE 5-2 GAS VENT TERMINATION LOCATIONS FOR

LISTED CAPS 12 INCH (300 MM) OR LESS IN SIZE NOT LESS

THAN 8 FEET (2.4 m) FROM A VERTICAL WALL

[NFPA 54: FIGURE 12.7.2 AND TABLE 12.7.2]

APPLIANCES TYPE OF VENTING SYSTEM

Listed Category I appliances Type B gas vent (510.6)

Listed appliances equipped withdraft hood

Chimney (510.5)

Appliances listed for Type B gasvent

Single-wall metal pipe (510.7)Listed chimney lining systemfor gas venting (510.5.1.3)Special gas vent listed for thisappliance (510.4.4)

Listed vented wall furnaces Type B-W gas vent (510.6,510.6.2.2)

Category II appliances

Category III appliances

Category IV appliances

As specified or furnished bymanufacturers of listed appli-ance (510.4.2, 510.4.4)

Incinerators, outdoors Single-wall metal pipe (510.7,510.7.3)

Incinerators, indoors

Appliances that can be convertedto use of solid fuel

Unlisted combination gas- andoil-burning appliances

Combination gas- and solid-fuel-burning appliances

Appliances listed for use withchimneys only

Unlisted appliances

Chimney (510.5)

Listed combination gas- andoil-burning appliances

Type L vent (510.6) or chimney(510.5)

Decorative appliance in ventedfireplace

Chimney [UMC 907.2(3)]

Gas-fired toilets Single-wall metal pipe (510.7,NFPA 54:10.25.3)

Direct-vent appliances See 510.2.5

Appliances with integral vent See 510.2.6

TABLE 5-2

TYPE OF VENTING SYSTEM TO BE USED

[NFPA 54: Table 12.5.1]

FIGURE 5-3 PLAN VIEW OF PRACTICAL SEPARATION

METHOD FOR MULTISTORY GAS VENTING.

[NFPA 54: FIGURE 12.7.4.2]

510.5.5.3 A listed combination gas- and solid-fuel-burning appliance connected to a single chimneyflue shall be equipped with a manual reset device toshut off gas to the main burner in the event of sus-tained backdraft or flue gas spillage. The chimneyflue shall be sized to properly vent the appliance.[NFPA 54:12.6.5.3]510.5.5.4Asingle chimney flue serving a listed com-bination gas- and oil-burning appliance shall be sizedto properly vent the appliance. [NFPA54:12.6.5.4]

510.5.6 Support of Chimneys. Portions of chimneysshall be supported for the design and weight of the ma-terials employed. Listed factory-built chimneys shall besupported and spaced in accordance with their listingsand the manufacturer’s instructions. [NFPA 54:12.6.6]510.5.7 Cleanouts.Where a chimney that formerly car-ried flue products from liquid- or solid-fuel-burning ap-pliances is used with an appliance using fuel gas, anaccessible cleanout shall be provided. The cleanout shallhave a tight-fitting cover and be installed so its upper edgeis at least six (6) inches (150 mm) below the lower edgeof the lowest chimney inlet opening. [NFPA 54:12.6.7]510.5.8 Space Surrounding Lining or Vent.

510.5.8.1 The remaining space surrounding a chim-ney liner, gas vent, special gas vent, or plastic pipinginstalled within a masonry chimney flue shall not beused to vent another appliance. [NFPA 54:12.6.8.1]Exception: The insertion of another liner or ventwithin the chimney as provided in this code and theliner or vent manufacturer's instructions.510.5.8.2 The remaining space surrounding a chim-ney liner, gas vent, special gas vent, or plastic pipinginstalled within a masonry chimney flue shall not beused to supply combustion air. [NFPA 54:12.6.8.2]Exception: Direct-vent gas-fired appliances de-signed for installation in a solid-fuel-burning fire-place where installed in accordance with the listingand the manufacturer’s instruction.

510.6 Gas Vents.510.6.1 A gas vent passing through a roof shall extendthrough the entire roof flashing, roof jack, or roof thim-ble and be terminated with a listed termination cap.[NFPA 54:12.7.2(6)]

510.6.1.1 Type B or Type L vents shall extend in agenerally vertical direction with offsets not exceed-ing 45 degrees, except that a vent system having notmore than one 60 degree offset shall be permitted.Any angle greater than 45 degrees from the verticalis considered horizontal. The total horizontal dis-tance of a vent plus the horizontal vent connectorserving draft-hood-equipped appliances shall not ex-ceed 75 percent of the vertical height of the vent.[NFPA 54:12.7.3.2]

Exception: Systems designed and sized as providedin this chapter or in accordance with other approvedengineering methods.510.6.1.2 Screws, rivets and other fasteners shall notpenetrate the inner wall of double wall gas vents.

510.6.2 A gas vent shall terminate in accordance withone of the following [NFPA 54:12.7.2(1)]:(1) Above the roof surface with a listed cap or listed

roof assembly. Gas vents twelve (12) inches (300mm) in size or smaller with listed caps shall be per-mitted to be terminated in accordance with Figure5-2, provided they are at least eight (8) feet (2.4 m)from a vertical wall or similar obstruction. Other gasvents shall terminate not less than two (2) feet (0.6m) above the highest point where they pass throughthe roof and at least two (2) feet (0.6 m) exceedingany portion of a building within ten (10) feet (3.1m). [NFPA 54:12.7.2(1)(a) and (b)]

(2) Industrial gas utilization appliances as provided inSection 510.2.4. [NFPA 54:12.7.2(1)(c)]

(3) Direct-vent systems as provided in Section 510.2.5.[NFPA 54:12.7.2(1)(d)]

(4) Appliances with integral vents as provided in Sec-tion 510.2.6. [NFPA 54:12.7.2(1)(e)]

(5) Mechanical draft systems as provided in Section510.3.4. [NFPA 54:12.7.2(1)(f)]

(6) Ventilating hoods and exhaust systems as providedin Section 510.3.5. [NFPA 54: 12.7.2(1)(g)]510.6.2.1 A Type B or a Type L gas vent shall ter-minate at least five (5) feet (1.5 m) in vertical heightabove the highest connected appliance draft hood orflue collar. [NFPA 54:12.7.2(2)]510.6.2.2 A Type B-W gas vent shall terminate atleast twelve (12) feet (3.7 m) in vertical height abovethe bottom of the wall furnace. [NFPA54:12.7.2(3)]510.6.2.3 A gas vent extending through an exteriorwall shall not terminate adjacent to the wall or beloweaves or parapets, except as provided in Sections510.2.5 and 510.3.4. [NFPA 54:12.7.2(4)]510.6.2.4 Decorative shrouds shall not be installed atthe termination of gas vents except where suchshrouds are listed for use with the specific gas ventingsystem and are installed in accordance with manufac-turer’s installation instructions. [NFPA54:12.7.2(5)]510.6.2.5 Gas vents shall extend through the roofflashing, roof jack, or roof thimble and terminatewith a listed cap or listed roof assembly. [NFPA54:12.7.2(6)]510.6.2.6Agas vent shall terminate at least three (3)feet (0.9 m) above a forced air inlet located withinten (10) feet (3.0 m). [NFPA 54:12.7.2(7)]

510.6.3 Size of Gas Vents. Venting systems shall besized and constructed in accordance with NFPA 54, Na-tional Fuel Gas Code, Chapter 13 or other approved en-gineering methods and the gas vent and gas appliancemanufacturer’s instructions. [NFPA 54:12.7.3]


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510.6.3.1 Category I Appliances. The sizing of nat-ural draft venting systems serving one (1) or morelisted appliances equipped with a draft hood or appli-ances listed for use with Type B gas vent, installed ina single story of a building, shall be in accordancewithone of the following methods [NFPA54:12.7.3.1]:(1) The provisions of this chapter. [NFPA

54:12.7.3.1(1)](2) Vents serving fan-assisted combustion system

appliances, or combinations of fan-assistedcombustion systems and draft hood-equippedappliances, shall be sized in accordance withthis chapter or other approved engineeringmethods. [NFPA 54:12.7.3.1(2)]

(3) For sizing an individual gas vent for a single,draft-hood-equipped appliance, the effectivearea of the vent connector and the gas vent shallbe at least the area of the appliance draft hoodoutlet or exceeding seven (7) times the drafthood outlet area. [NFPA 54:12.7.3.1(3)]

(4) For sizing a gas vent connected to two (2) ap-pliances with draft hoods, the effective area ofthe vent shall be at least the area of the largerdraft hood outlet plus 50 percent of the area ofthe smaller draft hood outlet or exceeding seven(7) times the smaller draft hood outlet area.[NFPA 54:12.7.3.1(4)]

(5) Approved engineering practices. [NFPA54:12.7.3.1(5)]

510.6.3.2 Category II, Category III, and CategoryIVAppliances. The sizing of gas vents for CategoryII, Category III, and Category IV gas utilization ap-pliances shall be in accordance with the equipmentmanufacturer's instructions. [NFPA 54:12.7.3.3]510.6.3.3 Sizing. Chimney venting systems usingmechanical draft shall be sized in accordance withapproved engineering methods. [NFPA54:12.7.3.4]

510.6.4 Gas Vents Serving Appliances on More ThanOne Floor.

510.6.4.1 A common gas vent shall be permitted inmultistory installations to vent Category I gas uti-lization appliances located on more than one (1)floor level, provided the venting system is designedand installed in accordance with approved engi-neering methods.

For the purpose of this section, crawl spaces,basements, and attics shall be considered as floorlevels. [NFPA 54:12.7.4.1]510.6.4.2Gas utilization appliances connected to thecommon vent shall be located in rooms separatedfrom a habitable space. Each of these rooms shallhave provisions for an adequate supply of combus-tion, ventilation, and dilution air that is not suppliedfrom a habitable space (See Figure 5-3). [NFPA54:12.7.4.2]

The size of the connectors and common seg-ments of multistory venting systems for gas utiliza-tion appliances listed for use with Type B double-wallgas vent shall be in accordance with Table 5-14, pro-vided [NFPA 54:12.7.4.3]:(1) The available total height (H) for each segment

of a multistory venting system is the verticaldistance between the level of the highest drafthood outlet or flue collar on that floor and thecenterline of the next highest interconnectiontee (See Figure G.1(K)). [NFPA54:12.7.4.3(1)]

(2) The size of the connector for a segment is de-termined from its gas utilization appliance heatinput and available connector rise, and shall notbe smaller than the draft hood outlet or flue col-lar size. [NFPA 54:12.7.4.3(2)]

(3) The size of the common vertical vent segment,and of the interconnection tee at the base of thatsegment, shall be based on the total gas uti-lization appliance heat input entering that seg-ment and its available total height. [NFPA54:12.7.4.3(3)]

510.6.5 Support of Gas Vents. Gas vents shall be sup-ported and spaced in accordance with their listings andthe manufacturer’s instructions. [NFPA 54:12.7.5]510.6.6 Marking. In those localities where solid and liq-uid fuels are used extensively, gas vents shall be perma-nently identified by a label attached to the wall or ceilingat a point where the vent connector enters the gas vent.The label shall read: "This gas vent is for appliances thatburn gas. Do not connect to solid- or liquid-fuel-burningappliances or incinerators." The Authority Having Juris-diction shall determine whether its area constitutes sucha locality. [NFPA 54:12.7.6]

510.7 Single-Wall Metal Pipe.510.7.1 Construction. Single-wall metal pipe shall beconstructed of galvanized sheet steel not less than 0.0304inch (0.7 mm) thick or of other approved, noncom-bustible, corrosion-resistant material. [NFPA 54:12.8.1]510.7.2 Cold Climate. Uninsulated single-wall metalpipe shall not be used outdoors in cold climates for vent-ing gas utilization appliances. For venting appliances inregions where the 99 percent winter design temperatureis below 32°F (0°C). [NFPA 54:12.8.2]510.7.3 Termination. The termination of single-wallmetal pipe shall comply with the following requirements[NFPA 54:12.8.3]:

510.7.3.1 Single-wall metal pipe shall terminate atleast five (5) feet (1.5 m) in vertical height above thehighest connected appliance draft hood outlet or fluecollar. [NFPA 54:12.8.3(1)]510.7.3.2 Single-wall metal pipe shall extend at leasttwo (2) feet (0.6 m) above the highest point where itpasses through the roof of a building and at least (2)feet (0.6 m) exceeding any portion of a buildingwithin a horizontal distance of ten (10) feet (3.1 m)(See Figure 5-1). [NFPA 54:12.8.3(2)]


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510.7.3.3 An approved cap or roof assembly shall beattached to the terminus of a single-wall metal pipe.[Also see Section 510.7.4.4.] [NFPA 54:12.8.3(3)]

510.7.4 Installation with Appliances Permitted by

510.4.1.

510.7.4.1 Prohibited Use. Single-wall metal pipe

shall not be used as a vent in dwellings and resi-

dential occupancies. [NFPA 54-09:12.8.4.1]

510.7.4.2 Single-wall metal pipe shall be used only

for runs directly from the space in which the gas uti-

lization appliance is located through the roof or ex-

terior wall to the outer air. A pipe passing through a

roof shall extend without interruption through the

roof flashing, roof jacket, or roof thimble. [NFPA

54:12.8.4.1]

510.7.4.3 Single-wall metal pipe shall not originate

in any unoccupied attic or concealed space and shall

not pass through any attic, inside wall, concealed

space, or floor. For the installation of a single-wall

metal pipe through an exterior combustible wall, see

Section 510.7.4.6. [NFPA 54:12.8.4.2]

510.7.4.4 Single-wall metal pipe used for venting an

incinerator shall be exposed and readily examinable

for its full length and shall have suitable clearances

maintained. [NFPA 54:12.8.4.3]

510.7.4.5 Minimum clearances from single-wall

metal pipe to combustible material shall be in ac-

cordance with Table 5-3. Reduced clearances from

single-wall metal pipe to combustible material shall

be as specified for vent connectors in Table 5-4.

[NFPA 54:12.8.4.4]

510.7.4.6 Single-wall metal pipe shall not pass

through a combustible exterior wall unless guarded at

the point of passage by a ventilated metal thimble not

smaller than the following [NFPA 54:12.11.14.2]:

(1) For listed appliances equipped with draft hoodsand appliances listed for use with Type B gasvents, the thimble shall be at a minimum four

(4) inches (100 mm) larger in diameter than themetal pipe. Where there is a run of at least six(6) feet (1.8 m) of metal pipe in the opening be-tween the draft hood outlet and the thimble, thethimble shall be a minimum two (2) inches (50mm) larger in diameter than the metal pipe.

(2) For unlisted appliances having draft hoods, the

thimble shall be a minimum six (6) inches (150

mm) larger in diameter than the metal pipe.

(3) For residential and low-heat appliances, the

thimble shall be a minimum twelve (12) inches

(300 mm) larger in diameter than the metal

pipe.

Exception: In lieu of thimble protection, com-

bustible material in the wall shall be removed a

sufficient distance from the metal pipe to provide

the specified clearance from such metal pipe to

combustible material. Any material used to close

up such opening shall be noncombustible.

510.7.4.7 Where a single-wall metal pipe passes

through a roof constructed of combustible material,

a noncombustible, nonventilating thimble shall be

used at the point of passage. The thimble shall ex-

tend not less than eighteen (18) inches (460 mm)

above and six (6) inches (150 mm) below the roof

with the annular space open at the bottom and closed

only at the top. The thimble shall be sized in accor-

dance with Section 510.7.4.6. [NFPA 54:12.8.4.5]

510.7.5 Size of Single-Wall Metal Pipe. Single-wall

metal piping shall comply with the following require-

ments [NFPA 54:12.8.5]:

510.7.5.1 A venting system of a single-wall metal

pipe shall be sized in accordance with one of the fol-

lowing methods and the gas appliance manufac-

turer's instructions [NFPA 54:12.8.5(1)]:

(1) For a draft-hood-equipped appliance, in accor-

dance with this chapter. [NFPA 54:12.8.5(1)(a)]


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TABLE 5-3

CLEARANCE FOR CONNECTORS [NFPA 54: TABLE 12.8.4.4]

For SI units, 1 in.= 25.4 mm.

Note: These clearances shall apply unless the listing of an appliance or connector specifies clearances, in which case the listed clearances shall apply.

MINIMUM DISTANCE FROM COMBUSTIBLE MATERIAL

APPLIANCE LISTED TYPE B GAS

VENT MATERIAL

LISTED TYPE L VENT

MATERIAL

SINGLE-WALL

METAL PIPE

FACTORY-BUILT

CHIMNEY SECTIONS

Listed appliances with draft hoods and appliances listed

for use with Type B gas vents

As listed As listed 6 in. As listed

Residential boilers and furnaces with listed gas conver-

sion burner and with draft hood

6 in. 6 in. 9 in. As listed

Residential appliances listed for use with Type L vents Not permitted As listed 9 in. As listed

Listed gas-fired toilets Not permitted As listed As listed As listed

Unlisted residential appliances with draft hood Not permitted 6 in. 9 in. As listed

Residential and low-heat appliances other than those

above

Not permitted 9 in. 18 in. As listed

Medium-heat appliances Not permitted Not permitted 36 in. As listed


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WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:

36 in. 18 in. 12 in. 9 in. 6 in.

ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (in.)

TYPE OF PROTECTION APPLIED

TO AND COVERING SURFACES

OF COMBUSTIBLE MATERIAL

WITHIN THE DISTANCE SPECI-

FIED AS THE REQUIRED CLEAR-

ANCE WITH NO PROTECTION

[SEE FIGURES 5-4 THROUGH 5-6]

USE COLUMN 1 FOR CLEARANCE ABOVE APPLIANCE OR HORIZONTAL CONNECTOR.

COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE

ABOVE

COLUMN 1

SIDES AND

REAR

COLUMN 2

ABOVE

COLUMN 1

SIDES AND

REAR

COLUMN 2

ABOVE

COLUMN 1

SIDES AND

REAR

COLUMN 2

ABOVE

COLUMN 1

SIDES AND

REAR

COLUMN 2

ABOVE

COLUMN 1

SIDES AND

REAR

COLUMN 2

(1) 31⁄2 in. thick masonry

wall without ventilated

air space

-- 24 -- 12 -- 9 -- 6 -- 5

(2) 1⁄2 in. insulation boardover 1 in. glass fiber ormineral wool batts

24 18 12 9 9 6 6 5 4 3

(3) 0.024 sheet metal over 1in. glass fiber or mineralwool batts reinforced withwire on rear face withventilated air space

18 12 9 6 6 4 5 3 3 3

(4) 31⁄2 in. thick masonry wallwith ventilated air space

-- 12 -- 6 -- 6 -- 6 -- 6

(5) 0.024 sheet metal withventilated air space

18 12 9 6 6 4 5 3 3 2

(6) 1⁄2 in. thick insulationboard with ventilated airspace

18 12 9 6 6 4 5 3 3 3

(7) 0.024 sheet metal withventilated air space over0.024 sheet metal withventilated air space

18 12 9 6 6 4 5 3 3 3

(8) 1 in. glass fiber or mineralwool batts sandwichedbetween two sheets 0.024sheet metal with venti-lated air space

18 12 9 6 6 4 5 3 3 3

TABLE 5-4

REDUCTION OF CLEARANCES WITH SPECIFIED FORMS OF PROTECTION [NFPA 54: TABLE 10.2.3(b)]

For SI units, 1 in. = 25.4 mm.Notes:1 Reduction of clearances from combustible materials shall not interfere with combustion air, draft hood clearance and relief, and accessibility of servicing.2 Clearances shall be measured from the outer surface of the combustible material to the nearest point on the surface of the appliance, disregarding any in-

tervening protection applied to the combustible material.3 Spacers and ties shall be of noncombustible material. No spacer or tie shall be used directly opposite the appliance or connector.4 Where clearance reduction systems use a ventilated air space, adequate provision for air circulation shall be provided as described. [See Figure 5-5 and

Figure 5-6.]5 There shall be at least one (1) in. (25 mm) between clearance reduction systems and combustible walls and ceilings for reduction systems using a venti-

lated air space.6 Where a wall protector is mounted on a single flat wall away from corners, it shall have a minimum one (1) inch (25 mm) air gap. To provide adequate air

circulation, the bottom and top edges, or only the side and top edges, or edges shall be left open.7 Mineral wool batts (blanket or board) shall have a minimum density of eight (8) lb/ft.3 (128 kg/m3) and a minimum melting point of 1500°F (816°C).8 Insulation material used as part of a clearance reduction system shall have a thermal conductivity of 1.0 Btu in./ft2/h-°F (0.144 W/m-K) or less.9 There shall be at least (1) inch (25 mm) between the appliance and the protector. In no case shall the clearance between the appliance and the combustible

surface be reduced below that allowed in this table.10 Clearances and thicknesses are minimum; larger clearances and thicknesses are acceptable.11 Listed single-wall connectors shall be installed in accordance with the terms of their listing and the manufacturer’s instructions.

(2) For a venting system for a single appliance witha draft hood, the areas of the connector and thepipe each shall be at least the area of the appli-ance flue collar or draft hood outlet, whicheveris smaller. The vent area shall not exceed seven(7) times the draft hood outlet area. [NFPA54:12.8.5(1)(b)]

(3) Other approved engineering methods. [NFPA54:12.8.5(1)(c)]

510.7.5.2Where a single-wall metal pipe is used andhas a shape other than round, it shall have an equiv-alent effective area equal to the effective area of theround pipe for which it is substituted, and the inter-nal dimension of the pipe shall be at least two (2)inches (50 mm). [NFPA 54:12.8.5(2)]510.7.5.3 The vent cap or a roof assembly shall havea venting capacity at least that of the pipe to whichit is attached. [NFPA 54:12.8.5(3)]

510.7.6 Support of Single-Wall Metal Pipe. Portionsof single-wall metal pipe shall be supported for the de-sign and weight of the material employed. [NFPA54:12.8.6]510.7.7 Marking. Single-wall metal pipe shall complywith the marking provisions of Section 510.6.6. [NFPA54:12.8.7]

510.8 Through-the-Wall Vent Termination (See Fig-ure 5-12).

510.8.1Amechanical draft venting system shall terminateat least three (3) feet (0.9 m) above any forced air inlet lo-cated within ten (10) feet (3.1 m). [NFPA 54:12.9.1]Exceptions:(1) This provision shall not apply to the combustion air

intake of a direct-vent appliance.


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Notes:

A – Equals the clearance with no protection specified in Tables 5-3 and 5-4and in the sections applying to various types of appliances.

B – Equals the reduced clearance permitted in accordance with Table 5-3.The protection applied to the construction using combustible material shallextend far enough in each direction to make C equal to A.

FIGURE 5-4 EXTENT OF PROTECTION NECESSARYTOREDUCE CLEARANCES FROM GAS APPLIANCES ORVENT

CONNECTORS [NFPA 54: FIGURE 10.3.2.2(1)]

Masonry walls can be attached to combustible walls using wall ties. Spac-ers should not be used directly behind appliance or connector.

FIGURE 5-5WALL PROTECTION REDUCTION SYSTEM.

[NFPA 54:FIGURE 10.3.2.2(2)]

FIGURE 5-6 MASONRY CLEARANCE REDUCTION SYSTEM.[NFPA 54: FIGURE 10.3.2.2(3)]

(2) This provision shall not apply to the separation ofthe integral outdoor air inlet and flue gas dischargeof listed outdoor appliances.

510.8.2Amechanical draft venting system of other thandirect-vent type shall terminate at least four (4) feet (1.2m) below, four (4) feet (1.2 m) horizontally from, or one(1) foot (300 mm) above any door, operable window, orgravity air inlet into any building. The bottom of the ventterminal shall be located at least twelve (12) inches (300mm) above finished grade. [NFPA 54:12.9.2]510.8.3The vent terminal of a direct-vent appliancewith aninput of 10,000 Btu/h (3 kW) or less shall be located at least(6) inches (150 mm) from any air opening into a building,and such an appliance with an input over 10,000 Btu/h (3kW) but not over 50,000 Btu/h (14.7 kW) shall be installedwith a nine (9) inch (230 mm) vent termination clearance,and an appliance with an input over 50,000 Btu/h (14.7kW) shall have at least a twelve (12) inch (300 mm) venttermination clearance. The bottom of the vent terminal andthe air intake shall be located at least twelve (12) inches(300 mm) above finished grade. [NFPA54:12.9.3]510.8.4 Through-the-wall vents for Category II and Cat-egory IV appliances and noncategorized condensing ap-pliances shall not terminate over public walkways orover an area where condensate or vapor could create anuisance or hazard or could be detrimental to the opera-tion of regulators, relief valves, or other equipment.Where local experience indicates that condensate is aproblem with Category I and Category III appliances,this provision shall also apply.

Drains for condensate shall be installed in accor-dance with the manufacturer’s installation instructions.[NFPA 54-09:12.9.4]510.8.5Where vents, including those for direct-vent ap-pliances or combustion air intake pipes, penetrate outsidewalls of buildings, the annular spaces around such pene-trations shall be permanently sealed using approved ma-terials to prevent entry of combustion products into thebuilding. [NFPA 54-09:12.9.5]

510.9 Condensation Drain.510.9.1 Provision shall be made to collect and disposeof condensate from venting systems serving Category IIand Category IV gas utilization appliances and noncate-gorized condensing appliances in accordance with Sec-tion 510.8.4. [NFPA 54:12.10.1]510.9.2Where local experience indicates that condensa-tion is a problem, provision shall be made to drain offand dispose of condensate from venting systems servingCategory I and Category III gas utilization appliances inaccordance with Section 510.8.4. [NFPA 54:12.10.2]

510.10 Vent Connectors for Category I Gas UtilizationAp-pliances.

510.10.1Where Required.Avent connector shall be usedto connect gas utilization appliances to a gas vent, chim-ney, or single-wall metal pipe, except where the gas vent,chimney, or single-wall metal pipe is directly connectedto the appliance. [NFPA 54:12.11.1]

510.10.2 Materials.510.10.2.1 A vent connector shall be made of non-combustible, corrosion resistant material capable ofwithstanding the vent gas temperature produced by thegas utilization appliance and of sufficient thickness towithstand physical damage. [NFPA54:12.11.2.1]510.10.2.2 Where the vent connector used for gasutilization appliances having a draft hood or a Cat-egory I appliance is located in or passes through anunconditioned area, that portion of the vent connec-tor shall be listed Type B, Type L, or listed vent ma-terial having equivalent insulation qualities. [NFPA54:12.11.2.2]Exception: Single-wall metal pipe located withinthe exterior walls of the building and located in areashaving a local 99 percent winter design temperatureof 5°F (-15°C) or higher.510.10.2.3 Where the vent connector used for gasutilization appliances having a draft hood or a Cat-egory I appliance is located in or passes through at-tics and crawl spaces, that portion of the ventconnector shall be listed Type B, Type L, or listedvent material having equivalent insulation qualities.[NFPA 54:12.11.2.3]510.10.2.4 Vent connectors for residential-type ap-pliances shall comply with the following [NFPA54:12.11.2.4]:(1) Vent connectors for listed gas appliances hav-

ing draft hoods and for appliances having drafthoods and equipped with listed conversionburners that are not installed in attics, crawlspaces, or other unconditioned areas shall beone of the following [NFPA 54:12.11.2.4(1)]:(a) Type B or Type L vent material.(b) Galvanized sheet steel at least 0.018 inches

(0.46 mm) thick.(c) Aluminum (1100 or 3003 alloy or equiva-

lent) sheet at least 0.027 inches (0.69 mm)thick.

(d) Stainless steel sheet at least 0.012 inches(0.31 mm) thick.

(e) Smooth interior wall metal pipe having re-sistance to heat and corrosion equal to orexceeding that of b, c, or d above.

(f) A listed vent connector.(2) Vent connectors shall not be covered with insu-

lation.Exception: Listed insulated vent connectorsshall be installed in accordance with the manu-facturer’s installation instructions. [NFPA54:12.11.2.4(2)]

510.10.2.5Avent connector for non-residential low-heat appliance shall be a factory-built chimney sec-tion or steel pipe having resistance to heat andcorrosion equivalent to that for the appropriate gal-vanized pipe as specified in Table 5-5. Factory-built


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chimney sections shall be joined together in accor-dance with the chimney manufacturer's instructions.[NFPA 54:12.11.2.5]

510.10.2.6 Vent connectors for medium-heat appli-ances and commercial and industrial incineratorsshall be constructed of factory-built, medium-heatchimney sections or steel of a thickness at least thatspecified in Table 5-6 and shall comply with the fol-lowing [NFPA 54:12.11.2.6]:(1) A steel vent connector for appliances with a

vent gas temperature exceeding 1,000°F(538°C) measured at the entrance to the con-nector shall be lined with medium-duty firebrick (ASTM C 64, Specification for Refracto-ries for Incinerators and Boilers, Type F) or theequivalent.

(2) The lining shall be at least two and one-half(21⁄2) inches (64 mm) thick for a vent connectorhaving a diameter or greatest cross-sectional di-mension of eighteen (18) inches (460 mm) orless.

(3) The lining shall be at least four and one-half(41⁄2) inches (110 mm) thick laid on the four andone-half (41⁄2) inch (110 mm) bed for a ventconnector having a diameter or cross-sectionaldimension exceeding eighteen (18) inches (460mm).

(4) Factory-built chimney sections, if employed,shall be joined together in accordance with thechimney manufacturer's instructions.

510.10.3 Size of Vent Connector.510.10.3.1 A vent connector for gas utilization ap-pliances with a single draft hood or for a Category Ifan-assisted combustion system appliance shall besized and installed in accordance with this chapteror other approved engineering methods. [NFPA54:12.11.3.1]510.10.3.2 For a single appliance having more thanone (1) draft hood outlet or flue collar, the manifoldshall be constructed according to the instructions ofthe appliance manufacturer. Where there are no in-structions, the manifold shall be designed and con-structed in accordance with approved engineeringpractices. As an alternate method, the effective areaof the manifold shall equal the combined area of theflue collars or draft hood outlets, and the vent con-nectors shall have a minimum one (1) foot (0.3 m)rise. [NFPA 54:12.11.3.2]510.10.3.3 Where two (2) or more gas appliancesare connected to a common vent or chimney, eachvent connector shall be sized in accordance with thischapter or other approved engineering methods.[NFPA 54:12.11.3.3] As an alternative method ap-plicable only when the appliances are draft-hood-equipped, each vent connector shall have aneffective area at least the area of the draft hood out-let of the appliance to which it is connected. [NFPA54:12.11.3.4]510.10.3.4 Where two (2) or more gas appliancesare vented through a common vent connector or ventmanifold, the common vent connector or vent man-ifold shall be located at the highest level consistentwith available head-room and clearance to com-bustible material and shall be sized in accordancewith this chapter or other approved engineeringmethods. [NFPA 54:12.11.3.5]

As an alternate method applicable only wherethere are two (2) draft-hood-equipped appliances,the effective area of the common vent connector orvent manifold and junction fittings shall be at leastthe area of the larger vent connector plus 50 percentof the areas of smaller flue collar outlets. [NFPA54:12.11.3.6]510.10.3.5Where the size of a vent connector is in-creased to overcome installation limitations and ob-tain connector capacity equal to the appliance input,the size increase shall be made at the appliance drafthood outlet. [NFPA 54:12.11.3.7]

510.10.4 Two orMoreAppliances Connected to a Sin-gle Vent.

510.10.4.1Where two (2) or more openings are pro-vided into one (1) chimney flue or vent, the openingsshall either be at different levels, or the connectorsshall be attached to the vertical portion of the chim-ney or vent at an angle of 45 degrees or less relativeto the vertical. [NFPA 54-09:12.11.4.1]


WATER HEATERS

TABLE 5-6MINIMUMTHICKNESS FOR STEEL VENT CONNECTORS FOR

MEDIUM-HEAT APPLIANCES AND COMMERCIAL ANDINDUSTRIAL INCINERATORS[NFPA 54:TABLE 12.11.2.6]

For SI units, 1 in. = 25.4 mm; 1 in.2 = 645 mm2.

DIAMETER OF CONNECTOR(in.)

MINIMUMTHICKNESS(in.)*

Less than 6 0.0196 to less than 10 0.02310 to 12 inclusive 0.02914 to 16 inclusive 0.034

Over 16 0.056

TABLE 5-5MINIMUMTHICKNESS FOR GALVANIZED STEEL VENT

CONNECTOR FOR LOW-HEAT APPLIANCES[NFPA 54:TABLE 12.11.2.5]

* For SI units, 1 in. = 25.4 mm; 1 in.2 = 645 mm2.

VENT CONNECTOR SIZE

DIAMETER (in.) AREA (in.2)MINIMUM

THICKNESS (in.)

Up to 14 Up to 154 0.053Over 14 to 16 154 to 201 0.067Over 16 to 18 201 to 254 0.093Over 18 Exceeding 254 0.123

510.10.4.2 Where two (2) or more vent connectorsenter a common gas vent, chimney flue, or single-wall metal pipe, the smaller connector shall enter atthe highest level consistent with the available head-room or clearance to combustible material. [NFPA54:12.11.4.1]510.10.4.3Vent connectors serving Category I appli-ances shall not be connected to any portion of a me-chanical draft system operating under positive staticpressure, such as those serving Category III or Cate-gory IV appliances. [NFPA 54:12.11.4.2]

510.10.5 Clearance.Minimum clearances from vent con-nectors to combustible material shall be in accordancewith Table 5-3. [NFPA 54:12.11.5]Exception: The clearance between a vent connector andcombustible material shall be permitted to be reducedwhere the combustible material is protected as specifiedfor vent connectors in Table 5-4.510.10.6 Avoid Unnecessary Bends. A vent connectorshall be installed so as to avoid turns or other constructionfeatures that create excessive resistance to flow of ventgases. [NFPA 54:12.11.6]510.10.7 Joints. Joints between sections of connector pip-ing and connections to flue collars or draft hood outletsshall be fastened in accordance with one of the followingmethods [NFPA 54:12.11.7]:(1) By sheet metal screws.(2) Vent connectors of listed vent material shall be as-

sembled and connected to flue collars or draft hoodoutlets in accordance with themanufacturer’s instruc-tions.

(3) Other approved means.510.10.8 Slope. A vent connector shall be installed with-out any dips or sags and shall slope upward toward thevent or chimney not less than one-quarter (1⁄4) inch/foot(20 mm/m). [NFPA 54:12.11.8]Exception:Vent connectors attached to a mechanical draftsystem installed in accordance with the appliance and draftsystem manufacturer’s instructions.510.10.9 Length of Vent Connector.

510.10.9.1 A vent connector shall be as short aspractical and the gas utilization appliance locatedas close as practical to the chimney or vent. [NFPA54:12.11.9.1]510.10.9.2 The maximum horizontal length of a sin-gle-wall connector shall be 75 percent of the heightof the chimney or vent except for engineered sys-tems. [NFPA 54-09:12.11.9.2]510.10.9.3 The maximum horizontal length of aType B double-wall connector shall be 100 percentof the height of the chimney or vent, except for en-gineered systems. The maximum length of an indi-vidual connector for a chimney or vent systemserving multiple appliances, from the appliance out-let to the junction with the common vent or anotherconnector, shall be 100 percent of the height of thechimney or vent. [NFPA 54:12.11.9.3]

510.10.10 Support.Avent connector shall be supportedfor the design and weight of the material employed tomaintain clearances and prevent physical damage andseparation of joints. [NFPA 54:12.11.10]510.10.11 Chimney Connection.Where entering a fluein a masonry or metal chimney, the vent connector shallbe installed above the extreme bottom to avoid stoppage.Where a thimble or slip joint is used to facilitate removalof the connector, the connector shall be firmly attachedto or inserted into the thimble or slip joint to prevent theconnector from falling out. Means shall be employed toprevent the connector from entering so far as to restrictthe space between its end and the opposite wall of thechimney flue. [NFPA 54:12.11.11]510.10.12 Inspection. The entire length of a vent con-nector shall be readily accessible for inspection, clean-ing, and replacement. [NFPA 54:12.11.12]510.10.13 Fireplaces.Avent connector shall not be con-nected to a chimney flue serving a fireplace unless thefireplace flue opening is permanently sealed. [NFPA54:12.11.13]510.10.14 Passage through Ceilings, Floors, orWalls.

510.10.14.1Avent connector shall not pass throughany ceiling, floor, or fire-resistance-rated wall.A sin-gle-wall metal pipe connector shall not pass throughany interior wall.Exception:Vent connectors made of listed Type B orType L vent material and serving listed applianceswith draft hoods and other appliances listed for usewith Type B gas vents that pass through walls or par-titions constructed of combustible material shall beinstalled with not less than the listed clearance tocombustible material.510.10.14.2 Vent connectors for medium-heat ap-pliances shall not pass through walls or partitionsconstructed of combustible material. [NFPA54:12.11.14.3]

510.11 Vent Connectors for Category II, Category III, andCategory IV Gas Utilization Appliances (See Section510.4). [NFPA 54:12.12]510.12 Draft Hoods and Draft Controls.

510.12.1 Appliances Requiring Draft Hoods. Ventedgas utilization appliances shall be installed with drafthoods. [NFPA 54:12.13.1]Exception: Dual oven-type combination ranges; incin-erators; direct-vent appliances; fan-assisted combustionsystem appliances; appliances requiring chimney draftfor operation; single firebox boilers equipped with con-version burners with inputs exceeding 400,000 Btu/h(117 kW); appliances equipped with blast, power, orpressure burners that are not listed for use with drafthoods; and appliances designed for forced venting.510.12.2 Installation. A draft hood supplied with orforming a part of listed vented gas utilization appliances


WATER HEATERS

shall be installed without alteration, exactly as furnished

and specified by the appliance manufacturer. [NFPA

54:12.13.2]

If a draft hood is not supplied by the appliance man-ufacturer where one (1) is required, a draft hood shall beinstalled, be of a listed or approved type, and, in the ab-sence of other instructions, be of the same size as the ap-pliance flue collar. Where a draft hood is required with aconversion burner, it shall be of a listed or approved type.[NFPA 54: 12.13.2.1]

Where it is determined that a draft hood of specialdesign is needed or preferable for a particular installa-tion, the installation shall be in accordance with the rec-ommendations of the appliance manufacturer and shallbe approved by the Authority Having Jurisdiction.[NFPA 54:12.13.2.2]

510.12.3 Draft-Control Devices. Where a draft-controldevice is part of the gas utilization appliance or is sup-plied by the appliance manufacturer, it shall be installedin accordance with the manufacturer's instructions. In theabsence of manufacturer's instructions, the device shallbe attached to the flue collar of the appliance or as nearto the appliance as practical. [NFPA 54:12.13.3]

510.12.4 Additional Devices. Gas utilization appliances(except incinerators) requiring controlled chimney draftshall be permitted to be equipped with a listed double-acting barometric draft regulator installed and adjustedin accordance with the manufacturer’s instructions.[NFPA 54:12.13.4]

510.12.5 Location. Draft hoods and barometric draft reg-ulators shall be installed in the same room or enclosureas the appliance in such a manner as to prevent any dif-ference in pressure between the hood or regulator and thecombustion air supply. [NFPA 54:12.13.5]

510.12.6 Positioning. Draft hoods and draft regulatorsshall be installed in the position for which they were de-signed with reference to the horizontal and verticalplanes and shall be located so that the relief opening isnot obstructed by any part of the appliance or adjacentconstruction. The appliance and its draft hood shall belocated so that the relief opening is accessible for check-ing vent operation. [NFPA 54:12.13.6]

510.12.7 Clearance. A draft hood shall be located so thatits relief opening is at least six (6) inches (150 mm) fromany surface except that of the appliance it serves and theventing system to which the draft hood is connected.Where a greater or lesser clearance is indicated on theappliance label, the clearance shall not be less than thatspecified on the label. Such clearances shall not be re-duced. [NFPA 54:12.13.7]

510.13 Manually Operated Dampers. A manually operateddamper shall not be placed in any appliance vent connector.Fixed baffles shall not be classified as manually operateddampers. [NFPA 54:12.14]

510.14 Automatically Operated Vent Dampers. An auto-matically operated vent damper shall be of a listed type.[NFPA 54:12.15]

510.15 Obstructions. Devices that retard the flow of ventgases shall not be installed in a vent connector, chimney, orvent. The following shall not be considered as obstructions[NFPA 54:12.16]:

(1) Draft regulators and safety controls specifically listed forinstallation in venting systems and installed in accor-dance with the terms of their listing.

(2) Approved draft regulators and safety controls designedand installed in accordance with approved engineeringmethods.

(3) Listed heat reclaimers and automatically operated ventdampers installed in accordance with the terms of theirlisting.

(4) Vent dampers serving listed appliances installed in ac-cordance with this chapter or other approved engineeringmethods.

(5) Approved economizers, heat reclaimers, and recupera-tors installed in venting systems of appliances not re-quired to be equipped with draft hoods, provided the gasutilization appliance manufacturer's instructions coverthe installation of such a device in the venting systemand performance in accordance with Sections 510.3.1and 510.3.2 is obtained.

511.0 Sizing of Category I Venting Systems.

511.1 These venting tables shall not be used where obstruc-tions (see Section 510.15) are installed in the venting system.The installation of vents serving listed appliances with ventdampers shall be in accordance with the appliance manufac-turer’s instructions or in accordance with the following[NFPA 54:13.1.1]:

(1) The maximum capacity of the vent system shall be de-termined using the NAT Max column.

(2) The minimum capacity shall be determined as though theappliance were a fan-assisted appliance, using the FANMin column to determine the minimum capacity of thevent system. Where the corresponding “FAN Min” is“NA” the vent configuration shall not be permitted andan alternative venting configuration shall be utilized.

511.1.1 Where the vent size determined from the tables

is smaller than the appliance draft hood outlet or flue col-

lar, the use of the smaller size shall be permitted provided

that the installation complies with the following require-

ments [NFPA 54:13.1.2]:

(1) The total vent height (H) is at least ten (10) feet (3

m).

(2) Vents for appliance draft hood outlets or flue collars

twelve (12) inches (300 mm) in diameter or smaller

are not reduced more than one (1) table size.

(3) Vents for appliance draft hood outlets or flue collars

exceeding twelve (12) inches (300 mm) in diameter

are not reduced more than two (2) table sizes.

(4) The maximum capacity listed in the tables for a fan-as-sisted appliance is reduced by 10 percent (0.90 maxi-mum table capacity).


WATER HEATERS

(5) The draft hood outlet exceeds four (4) inches (100mm) in diameter. Do not connect a three (3) inch (80mm) diameter vent to a four (4) inch (100 mm) diam-eter draft hood outlet. This provision shall not apply tofan-assisted appliances.

511.1.2 Elbows. Single-appliance venting configurationswith zero (0) lateral lengths in Tables 5-8, 5-9, and 5-12shall have no elbows in the venting system. Single-ap-pliance venting with lateral lengths, include allowancefor two (2) 90 degree elbows. For each additional elbowup to and including 45 degrees, the maximum capacitylisted in the venting tables shall be reduced by 5 percent.For each additional elbow exceeding 45 degrees up toand including 90 degrees, the maximum capacity listedin the venting tables shall be reduced by 10 percent.[NFPA 54:13.1.3]

Where multiple offsets occur in a vent, the total lat-eral length of all offsets combined shall not exceed thatspecified in Tables 5–8 through 5–12. [NFPA 54-09:13.1.3]511.1.3 Zero (0) lateral (L) shall apply only to a straightvertical vent attached to a top outlet draft hood or fluecollar. [NFPA 54:13.1.4]511.1.4 Sea level input ratings shall be used when deter-mining maximum capacity for high-altitude installation.Actual input (derated for altitude) shall be used for de-termining minimum capacity for high-altitude installa-tion. [NFPA 54:13.1.5]511.1.5 For appliances with more than one (1) input rate,the minimum vent capacity (FANMin) determined fromthe tables shall be less than the lowest appliance inputrating, and the maximum vent capacity (FAN Max/NATMax) determined from the tables shall exceed the high-est appliance rating input. [NFPA 54:13.1.6]511.1.6 Listed corrugated metallic chimney liner systemsin masonry chimneys shall be sized by using Tables 5-8or 5-9 for Type B vents with the maximum capacity re-duced by 20 percent (0.80 maximum capacity) and theminimum capacity as shown in Tables 5-8 or 5-9.

Corrugated metallic liner systems installed withbends or offsets shall have their maximum capacity fur-ther reduced in accordance with Section 511.1.2. The 20percent reduction for corrugated metallic chimney linersystems includes an allowance for one (1) long radius 90degree turn at the bottom of the liner. [NFPA 54:13.1.7]511.1.7 Connection to Chimney Liners. Connectionsbetween chimney liners and listed double-wall connec-tors shall be made with listed adapters designed for suchpurposes. [NFPA 54:13.1.8]511.1.8 Vertical Vent Upsizing 7 x Rule.Where the ver-tical vent has a larger diameter than the vent connector,the vertical vent diameter shall be used to determine theminimum vent capacity, and the connector diameter shallbe used to determine the maximum vent capacity. The

flow area of the vertical vent shall not exceed seven (7)times the flow area of the listed appliance categorizedvent area, flue collar area, or draft hood outlet area unlessdesigned in accordance with approved engineering meth-ods. [NFPA 54:13.1.9]511.1.9 Draft Hood Conversion Accessories. Drafthood conversion accessories for use with masonry chim-neys venting listed Category I fan-assisted appliancesshall be listed and installed in accordance with the listedaccessory manufacturer’s installation instructions.[NFPA 54:13.1.10]511.1.10 Tables 5-8 through 5-12 shall be used for chim-neys and vents not exposed to the outdoors below theroof line. AType B vent or listed chimney lining systempassing through an unused masonry chimney flue shallnot be considered to be exposed to the outdoors. A TypeB vent passing through an unventilated enclosure orchase insulated to a value of at least R8 shall not be con-sidered to be exposed to the outdoors. Table 5-10 in com-bination with Table 5-13 shall be used for clay-tile-linedexterior masonry chimneys, provided the following aremet [NFPA 54:13.1.11]:(1) The vent connector is Type B double wall.(2) The vent connector length is limited to one and one-

half (11⁄2) feet for each inch (18 mm/mm) of ventconnector diameter.

(3) The appliance is draft-hood-equipped.(4) The input rating is less than the maximum capacity

given in Table 5-10.(5) For a water heater, the outdoor design temperature

shall be not less than 5°F (-15°C).(6) For a space-heating appliance, the input rating ex-

ceeds the minimum capacity given by Table 5-13.511.1.11 Corrugated vent connectors shall not be smallerthan the listed appliance categorized vent diameter, fluecollar diameter, or draft hood outlet diameter. [NFPA54:13.1.12]511.1.12 Vent connectors shall not be upsized more thantwo (2) sizes exceeding the listed appliance categorizedvent diameter, flue collar diameter, or draft hood outletdiameter. [NFPA 54:13.1.13]511.1.13 In a single run of vent or vent connector, morethan one (1) diameter and type shall be permitted to beused, provided that the sizes and types are permitted bythe tables. [NFPA 54:13.1.14]511.1.14 Interpolation shall be permitted in calculatingcapacities for vent dimensions that fall between table en-tries (See Part II-Example G.1.3). [NFPA 54:13.1.15]511.1.15 Extrapolation beyond the table entries shall notbe permitted. [NFPA 54:13.1.16]511.1.16 For vent heights lower than six (6) feet and ex-ceeding vent heights shown in the tables, engineeringmethods shall be used to calculate vent capacities. [NFPA54:13.1.17]


WATER HEATERS

511.2 Additional Requirements to Multiple ApplianceVent Table 5-14 through Table 5-22.

511.2.1 Obstructions and Vent Damper. These ventingtables shall not be used where obstructions (See Section510.15) are installed in the venting system. The installa-tion of vents serving listed appliances with vent dampersshall be in accordance with the appliance manufacturer’sinstructions or in accordance with the following [NFPA54:13.2.1]:(1) The maximum capacity of the vent connector shall

be determined using the NAT Max column.(2) The maximum capacity of the vertical vent or chim-

ney shall be determined using the FAN + NAT col-umn when the second appliance is a fan-assistedappliance, or the NAT + NAT column when the sec-ond appliance is equipped with a draft hood.

(3) The minimum capacity shall be determined as if theappliance were a fan-assisted appliance.(a) The minimum capacity of the vent connector

shall be determined using the FANMin column.(b) The FAN + FAN column shall be used when the

second appliance is a fan-assisted appliance,and the FAN + NAT column shall be used whenthe second appliance is equipped with a drafthood, to determine whether the vertical vent orchimney configuration is not permitted (NA).Where the vent configuration is NA, the ventconfiguration shall not be permitted and an al-ternative venting configuration shall be utilized.

511.2.2 The vent connector horizontal length shall beeighteen (18) inches/inch (18 mm/mm) of connector di-ameter as shown in Table 5-7. [NFPA 54:13.2.2]511.2.3 The vent connector shall be routed to the ventutilizing the shortest possible route. Connectors withlonger horizontal lengths than those listed in Table 5-7are permitted under the following conditions [NFPA54:13.2.3]:(A) The maximum capacity (FANMax or NATMax) of

the vent connector shall be reduced 10 percent foreach additional multiple of the length listed in Table5-7. For example, the length listed for a four (4) inch(100 mm) connector shall not exceed six (6) feet (1.8m). With a connector length exceeding six (6) feet(1.8 m) but not exceeding twelve (12) feet (3.7 m),the maximum capacity must be reduced by 10 per-cent (0.90 maximum vent connector capacity). Witha connector length exceeding twelve (12) feet (3.7m) but not exceeding eighteen (18) feet (5.5 m), themaximum capacity must be reduced by 20 percent(0.80 maximum vent capacity) [NFPA54:13.2.3(1)].

(B) For a connector serving a fan-assisted appliance, theminimum capacity (FANMin) of the connector shallbe determined by referring to the corresponding sin-gle appliance table. For Type B double-wall con-nectors, Table 5-8 shall be used. For single-wallconnectors, Table 5-9 shall be used. The height (H)and lateral (L) shall be measured according to the

procedures for a single appliance vent, as if the otherappliances were not present. [NFPA 54:13.2.3(2)]

511.2.4Where the vent connectors are combined prior toentering the vertical portion of the common vent to forma common vent manifold, the size of the common ventmanifold and the common vent shall be determined byapplying a 10 percent reduction (.90 x maximum com-mon vent capacity) to the Common Vent Capacity partof the common vent tables. The length of the commonvent connector manifold (LM) shall not exceed eighteen(18) inches/inch (18 mm/mm) of common vent connec-tor manifold diameter (D) (See Part II-Figure G.1(k)).[NFPA 54:13.2.4]511.2.5 Vent Offset.Where the common vertical vent isoffset, the maximum capacity of the common vent shallbe reduced in accordance with Section 511.2.6, and thehorizontal length of the common vent offset shall not ex-ceed eighteen (18) inches/inch (18 mm/mm) of commonvent diameter. Where multiple offsets occur in a com-mon vent, the total horizontal length of offsets combinedshall not exceed eighteen (18) inches/inch (18 mm/mm)of common vent diameter. [NFPA 54:13.2.5]511.2.6 For each elbow up to and including 45 degrees inthe common vent, the maximum common vent capacitylisted in the venting tables shall be reduced by 5 percent.For each elbow exceeding 45 degrees up to and includ-ing 90 degrees, the maximum common vent capacitylisted in the venting tables shall be reduced by 10 per-cent. [NFPA 54:13.2.6]511.2.7 Common Vent Minimum Size. The cross-sec-tional area of the common vent shall be equal to or ex-ceeding the cross-sectional area of the largest connector.[NFPA 54:13.2.8]


WATER HEATERS

CONNECTOR DIAMETER

MAXIMUM (in.)

CONNECTOR HORIZONTAL

LENGTH (ft.)

3 41⁄24 65 71⁄26 97 101⁄28 129 131⁄210 1512 1814 2116 2418 2720 3022 3324 36

TABLE 5-7VENT CONNECTOR MAXIMUM LENGTH

[NFPA 54:TABLE 13.2.2]

For SI units, 1 in. = 25.4 mm; 1 ft. = 0.305 m.

511.2.8 Tee andWye Fittings. Tee and wye fittings con-nected to a common gas vent shall be considered as partof the common gas vent and constructed of materialsconsistent with that of the common gas vent. [NFPA 54-09:13.2.9]511.2.9At the point where tee or wye fittings connect toa common vent, the opening size of the fitting shall beequal to the size of the common vent. Such fittings shallnot be prohibited from having reduced size openings atthe point of connection of appliance vent connectors.[NFPA 54:13.2.10]511.2.10 Sea level input ratings shall be used when de-termining maximum capacity for high-altitude installa-tion. Actual input (derated for altitude) shall be used fordetermining minimum capacity for high-altitude instal-lation. [NFPA 54:13.2.11]511.2.11 The connector rise (R) for each appliance con-nector shall be measured from the draft hood outlet orflue collar to the centerline where the vent gas streamscome together. [NFPA 54:13.2.12]511.2.12 For multiple units of gas utilization applianceslocated on one (1) floor, available total height (H) shallbe measured from the highest draft hood outlet or fluecollar up to the level of the outlet of the common vent.[NFPA 54:13.2.13]511.2.13 For multistory installations, available totalheight (H) for each segment of the system shall be thevertical distance between the highest draft hood outlet orflue collar entering that segment and the centerline of thenext higher interconnection tee (See Part II-FigureG.1(m)). [NFPA 54:13.2.14]511.2.14 The size of the lowest connector and of the ver-tical vent leading to the lowest interconnection of a mul-tistory system shall be in accordance with Tables 5-8 or5-9 for available total height (H) up to the lowest inter-connection (See Part II-Figure G.1(n)). [NFPA54:13.2.15]511.2.15Where used in multistory systems, vertical com-mon vents shall be Type B double-wall and shall be in-stalled with a listed vent cap. [NFPA 54:13.2.16]511.2.16 Offsets in multistory common vent systemsshall be limited to a single offset in each system, and sys-tems with an offset shall comply with all of the follow-ing [NFPA 54:13.2.17]:(1) The offset angle shall not exceed 45 degrees from

vertical.(2) The horizontal length of the offset shall not exceed

eighteen (18) inches for each inch (180 mm/mm) ofcommon vent diameter of the segment in which theoffset is located.

(3) For the segment of the common vertical vent con-taining the offset, the common vent capacity listed inthe common venting tables shall be reduced by 20percent (0.80 x maximum common vent capacity).

(4) A multistory common vent shall not be reduced insize above the offset.

511.2.17 Where two (2) or more appliances are con-nected to a vertical vent or chimney, the flow area of thelargest section of vertical vent or chimney shall not ex-ceed seven (7) times the smallest listed appliance cate-gorized vent areas, flue collar area, or draft hood outletarea unless designed in accordance with approved engi-neering methods. [NFPA 54:13.2.18]511.2.18 For appliances with more than one (1) inputrate, the minimum vent connector capacity (FAN Min)determined from the tables shall be less than the lowestappliance input rating, and the maximum vent connectorcapacity (FAN Max or NAT Max) determined from thetable shall exceed the highest appliance input rating.[NFPA 54:13.2.19]511.2.19 Listed corrugated metallic chimney liner sys-tems in masonry chimneys shall be sized by using Tables5-14 or 5-15 for Type B vents, with the maximum ca-pacity reduced by 20 percent (0.80 maximum capacity)and the minimum capacity as shown in Tables 5-14 or 5-15. Corrugated metallic liner systems installed withbends or offsets shall have their maximum capacity fur-ther reduced in accordance with Sections 511.2.5 and511.2.6. The 20 percent reduction for corrugated metal-lic chimney liner systems includes an allowance for one(1) long radius 90 degree turn at the bottom of the liner.[NFPA 54:13.2.20]511.2.20 Tables 5-14 and 5-15 shall be used for chim-neys and vents not exposed to the outdoors below theroof line. AType B vent passing through an unventilatedenclosure or chase insulated to a value of not less than R8shall not be considered to be exposed to the outdoors. Ta-bles 5-19 and 5-20 shall be used for clay-tile-lined exte-rior masonry chimneys, provided all of the followingconditions are met [NFPA 54:13.2.22]:(1) Vent connector is Type B double-wall.(2) One (1) appliance is draft-hood-equipped.(3) The combined appliance input rating is less than the

maximum capacity given by Table 5-19 (for NAT +NAT) or Table 5-21 (for FAN + NAT).

(4) The input rating of each space-heating appliance ex-ceeds the minimum input rating given by Table 5-20(for NAT + NAT) or Table 5-22 (for FAN + NAT).

(5) The vent connector sizing is in accordance withTable 5-16.

511.2.21 Vent connectors shall not be increased morethan two (2) sizes exceeding the listed appliance catego-rized vent diameter, flue collar diameter, or draft hoodoutlet diameter. Vent connectors for draft-hood-equippedappliances shall not be smaller than the draft hood outletdiameter. Where vent connector sizes determined fromthe tables for fan-assisted appliances are smaller than theflue collar diameter, the use of the smaller sizes shall bepermitted provided that the installation complies with allof the following conditions [NFPA 54:13.2.24]:(1) Vent connectors for fan-assisted appliance flue col-

lars twelve (12) inches (300 mm) in diameter or


WATER HEATERS

smaller are not reduced by more than one (1) tablesize [e.g., twelve (12) inches to ten (10) inches (300mm to 250 mm) is a one (1) size reduction] andthose exceeding twelve (12) inches (300 mm) in di-ameter are not reduced exceeding two (2) table sizes[e.g., twenty-four (24) inch to twenty (20) inch (610mm to 510 mm) is a two (2) size reduction].

(2) Fan-assisted appliances are common vented with adraft-hood-equipped appliance.

(3) The vent connector has a smooth interior wall.511.2.22 Combinations of pipe sizes, single-wall, anddouble-wall metal pipe shall be allowed within any con-nector run or within the common vent, provided ALL ofthe appropriate tables permit ALL of the desired sizesand types of pipe, as if they were used for the entirelength of the subject connector or vent. Where single-wall and Type B double-wall metal pipes are used forvent connectors within the same venting system, thecommon vent must be sized using Tables 5-15 or 5-17 asappropriate. [NFPA 54:13.2.25]511.2.23Where a table permits more than one (1) diam-eter of pipe to be used for a connector or vent, all the per-mitted sizes shall be permitted to be used. [NFPA54:13.2.26]511.2.24 Interpolation shall be permitted in calculatingcapacities for vent dimensions that fall between table en-tries (See Part II Annex G.1.3). [NFPA 54:13.2.27]511.2.25 Extrapolation beyond the table entries shall notbe permitted. [NFPA 54:13.2.28]511.2.26 For vent heights lower than six (6) feet and ex-ceeding vent heights shown in the tables, engineeringmethods shall be used to calculate vent capacities. [NFPA54:13.2.29]

512.0 Direct-Vent Appliances.Listed direct-vent gas utilization appliances shall be consid-ered properly vented where installed in accordance with theterms of its listing, the manufacturer’s instructions, and Sec-tion 510.8.3. [NFPA 54:12.3.5]


WATER HEATERS

FIGURE 5-7 ALL COMBUSTION AIR FROM ADJACENT INDOORSPACESTHROUGH INDOOR COMBUSTION AIR OPENINGS.

[NFPA 54: FIGURE A.9.3.2.3(1)]


WATER HEATERS

FIGURE 5-8 ALL COMBUSTION AIR FROM OUTDOORS.INLET AIR FROMVENTILATED CRAWL SPACE AND

OUTLET AIRTOVENTILATED ATTIC.[NFPA 54: FIGURE A.9.3.3.1(a)]

FIGURE 5-10 ALL COMBUSTION AIR FROMOUTDOORSTHROUGH HORIZONTAL DUCTS.

[NFPA 54: FIGURE A.9.3.3.1(2)]

FIGURE 5-9 ALL COMBUSTION AIR FROMOUTDOORSTHROUGHVENTILATED ATTIC.

[NFPA 54: FIGURE A.9.3.3.1(1)(b)]

FIGURE 5-11 ALL COMBUSTION AIR FROM OUTDOORSTHROUGH SINGLE COMBUSTION AIR OPENING.

[NFPA 54: FIGURE A.9.3.3.2]


WATER HEATERS

FIGURE 5-12 EXITTERMINALS OF MECHANICAL DRAFT ANDDIRECT-VENTVENTING SYSTEMS. [NFPA 54: FIGURE A.12.9]

FIGURE 5-13 RANGE OFWINTER DESIGNTEMPERATURES USED IN ANALYZINGEXTERIOR MASONRY CHIMNEYS INTHE UNITED STATES. [NFPA 54: FIGURE G.2.4]


WATER HEATERS

TABLE 5-8TYPE B DOUBLE-WALL GASVENT [NFPA 54:TABLE 13.1(a)]

NUMBER OF APPLIANCES: SINGLE

APPLIANCETYPE: CATEGORY I

APPLIANCEVENT CONNECTION: CONNECTED DIRECTLYTOVENT

VENT DIAMETER – D (inch)

3 4 5 6 7

APPLIANCE INPUT RATING INTHOUSANDS OF BTU PER HOUR

HEIGHTH(ft)

LATERALL(ft)

FAN NAT FAN NAT FAN NAT FAN NAT FAN NAT

Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max

6 0246

0132125

78514946

46363432

0183036

152979491

86676461

0273947

251157153149

141105103100

0325059

375232227223

205157153149

0446678

524321316310

285217211205

8 0258

0122328

84575349

50403835

0163239

16510910398

94757166

0254251

276178171164

155120115109

0285364

415263255247

235180173165

0427084

583365356347

320247237227

10 02510

0122330

88615751

53424036

0173241

175118113104

100817770

0234154

295194187176

166129124115

0265267

447289280267

255195188175

0406888

631402392376

345273263245

15 0251015

011222935

9469655953

5848454137

015304048

191136130121112

11293878276

020395161

327226219206195

187150142135128

022496476

502339330315301

285225217208198

038648498

716475463445429

390316300288275

20 025101520

01021283448

977571645852

615148444035

01429384655

202149143133124116

11910096898478

01838505969

349250242229217206

202166160150142134

02047627384

540377367351337322

307249241228217206

033628194107

776531519499481464

430346337321308295

30 02510152030

0921273356NA

1008177706458NA

64565450NANANA

0132837445373

213166160150141132113

1281121081029690NA

0143648576688

374283275262249237214

220185176171163154NA

01845597080104

587432421405389374346

336280273261249237219

027587790102131

853613600580560542507

475394385371357343321

50 02510152030

08202659NANA

10186827670NANA

6761NANANANANA

0112735425069

216183177168158149131

134122119114NANANA

0143545546384

397320312299287275250

232206200190180169NA

0154356667699

633497487471455440410

363314308298288278259

02255738597123

932715702681662642605

518445438426413401376

100 0251015203050

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

01026334047NANA

218194189182174166NANA

NANANANANANANANA

0123343505978NA

407354347335321311290NA

NANANANANANANANA

0134053627192147

665566557542528513483428

400375369361353344NANA

01852688090115180

997831820801782763726651

560510504493482471449405

For SI units, 1 in. = 25.4 mm, 1 ft. = 0.305 m, 1,000 Btu/hr = 0.293 kW, 1 in.2 = 645 mm2.


WATER HEATERS




VENT DIAMETER – D ( inch)

8 9 10 12 14


HEIGHTH(ft)

LATERALL(ft)



6 0246

0537993

698425419413

370285279273

06393110

897543536530

470370362354

075110128

1,121675668661

570455445435

0103147171

1,645982975967

850650640630

0138191219

2,2671,3461,3381,330

1,170890880870

8 0258

0508399

780483473463

415322313303

06099117

1,006619607596

537418407396

071115137

1,261770758746

660515503490

098154180

1,8581,1241,1101,097

970745733720

0130199231

2,5711,5431,5281,514

1,3201,0201,0101,000

10 02510

04881104

847533522504

450355346330

05795122

1,096684671651

585457446427

068112142

1,377852839817

720560547525

093149187

2,0361,2441,2291,204

1,060850829795

0124192238

2,8251,7131,6961,669

1,4501,1301,1051,080

15 0251015

0457699115

970633620600580

525414403386373

05390116134

1,263815800777755

682544529507491

063105135155

1,5961,0191,003977953

840675660635610

086140177202

2,3801,4951,4761,4461,418

1,240985967936905

0114182227257

3,3232,0622,0412,0091,976

1,7201,3501,3271,2891,250

20 025101520

0417395111125

1,057711697675654634

575470460443427410

05086112129145

1,384917902877853830

752612599576557537

059101130150167

1,7561,1501,1331,1051,0781,052

930755738710688665

081135172195217

2,6371,6941,6741,6411,6091,578

1,3501,1001,0791,0451,018990

0107174220248273

3,7012,3432,3202,2822,2452,210

1,9001,5201,4981,4601,4251,390

30 02510152030

0336991105119149

1,173826811788765743702

650535524507490473444

04282107124139171

1,5481,0721,0551,0281,002977929

855700688668648628594

05496125143160195

1,9771,3511,3321,3011,2721,2431,189

1,060865851829807784745

074127164187207246

3,0042,0041,9811,9441,9081,8731,807

1,5501,3101,2891,2541,2201,1851,130

098164209237260305

4,2522,7862,7592,7162,6742,6332,555

2,1701,8001,7751,7331,6921,6501,585

50 02510152030

0266586100113141

1,297975960935911888844

708615605589572556522

03377101117131161

1,7301,2761,2591,2301,2031,1761,125

952813798773747722670

04190118136151183

2,2311,6201,6001,5671,5361,5051,446

1,1951,010996972948924876

066118154177195232

3,4412,4312,4062,3662,3272,2882,214

1,8251,5131,4951,4661,4371,4081,349

086151196222244287

4,9343,4093,3803,3323,2853,2393,150

2,5502,1252,1022,0642,0261,9871,910

100 0251015203050

021608093105131197

1,4111,1551,1411,1181,0951,0731,029944

770700692679666653627575

0257194109122149217

1,9081,5361,5191,4921,4651,4381,3871,288

1,040935926910895880849787

03082108126141170241

2,4911,9751,9551,9231,8921,8611,8021,688

1,3101,1701,1591,1421,1241,1071,0711,000

044107142163181215292

3,9253,0273,0022,9612,9202,8802,8032,657

2,0501,8201,8031,7751,7471,7191,6631,550

072136180206226265350

5,7294,3134,2824,2314,1824,1334,0373,856

2,9502,5502,5312,5002,4692,4382,3752,250

TABLE 5-8TYPE B DOUBLE-WALL GASVENT [NFPA 54:TABLE 13.1(a)] (continued)



WATER HEATERS





16 18 20 22 24


HeightH(ft)

LateralL(ft)



6 0246

0178242276

2,9831,7691,7611,753

1,5301,1701,1601,150

0225300341

3,8022,2502,2422,235

1,9601,4801,4751,470

0296390437

4,7212,7822,7742,767

2,4301,8501,8351,820

0360469523

5,7373,3773,3703,363

2,9502,2202,2152,210

0426555618

6,8534,0304,0234,017

3,5202,6702,6602,650

8 0258

0168251289

3,3992,0302,0132,000

1,7401,3401,3301,320

0212311354

4,3332,5842,5632,552

2,2201,7001,6851,670

0278398450

5,3873,1963,1803,163

2,7502,1102,0902,070

0336476537

6,5553,8823,8633,850

3,3602,5602,5452,530

0401562630

7,8384,6344,6124,602

4,0103,0503,0403,030

10 02510

0161243298

3,7422,2562,2382,209

1,9251,4801,4611,430

0202300364

4,7822,8682,8492,818

2,4501,8901,8711,840

0264382459

5,9553,5563,5363,504

3,0502,3402,3182,280

0319458546

7,2544,3224,3014,268

3,7102,8402,8182,780

0378540641

8,6825,1535,1325,099

4,4503,3903,3713,340

15 0251015

0147229283318

4,4232,7192,6962,6592,623

2,2701,7701,7481,7121,675

0186283346385

5,6783,4673,4423,4023,363

2,9002,2602,2352,1932,150

0239355432479

7,0994,3044,2784,2344,192

3,6202,8002,7772,7392,700

0290426510564

8,6655,2325,2045,1595,115

4,4103,4103,3853,3433,300

0346501599665

10,3936,2516,2226,1756,129

5,3004,0804,0574,0193,980

20 025101520

0139219273306335

4,9483,0973,0713,0292,9882,948

2,5202,0001,9781,9401,9101,880

0175270334372404

6,3763,9553,9263,8803,8353,791

3,2502,5702,5442,5002,4652,430

0220337413459495

7,9884,9164,8854,8354,7864,737

4,0603,2003,1743,1303,0903,050

0269403489541585

9,7855,9835,9505,8965,8445,792

4,9803,9103,8803,8303,7953,760

0321475573631689

11,7537,1547,1197,0637,0076,953

6,0004,7004,6624,6004,5754,550

30 02510152030

0127206259292319369

5,7253,6963,6663,6173,5703,5233,433

2,9202,3802,3502,3002,2502,2002,130

0159252316354384440

7,4204,7344,7014,6474,5944,5424,442

3,7703,0503,0202,9702,9202,8702,785

0199312386431467540

9,3415,9005,8635,8035,7445,6865,574

4,7503,8103,7833,7393,6953,6503,565

0241373456507548635

11,4837,1947,1557,0907,0266,9646,842

5,8504,6504,6224,5744,5274,4804,375

0285439535590639739

13,8488,6178,5748,5058,4378,3708,239

7,0605,6005,5525,4715,3915,3105,225

50 02510152030

0113191243274300347

6,7114,5544,5204,4644,4094,3564,253

3,4402,8402,8132,7672,7212,6752,631

0141234295330361412

8,7745,8645,8265,7635,7015,6415,523

4,4603,6703,6393,5853,5343,4813,431

0171283355396433494

11,1297,3397,2957,2247,1557,0866,953

5,6354,6304,5974,5424,5114,4794,421

0209336419465506577

13,7678,9808,9338,8558,7798,7048,557

6,9405,6955,6545,5855,5465,5065,444

0251394491542586672

16,69410,78810,73710,65210,57010,48810,328

8,4306,8606,8186,7496,7106,6706,603

100 0251015203050

095172223252277319415

7,9145,8345,7975,7375,6785,6195,5055,289

4,0503,5003,4753,4343,3923,3513,2673,100

0120208268304330378486

10,4857,5917,5487,4787,4097,3417,2096,956

5,3004,6004,5664,5094,4514,3944,2794,050

0138245318358387446572

13,4549,5779,5289,4479,3679,2899,1368,841

6,7005,8005,7695,7175,6655,6135,5095,300

0169293374418452514659

16,81711,80311,74811,65811,56911,48211,31010,979

8,6007,2007,1627,1007,0376,9756,8506,600

0204341436487523592752

20,57814,26414,20414,10514,00713,91013,72013,354

10,3008,8008,7568,6838,6108,5378,3918,100

TABLE 5-8TYPE B DOUBLE-WALL GASVENT [NFPA 54: TABLE 13.1(a)] (continued)



WATER HEATERS



APPLIANCEVENT CONNECTION: SINGLE-WALL METAL CONNECTOR


3 4 5 6 7


HEIGHTH(ft)

LATERALL(ft)



6 0246

3839NANA

7751NANA

45363331

59607483

151969289

85666360

8585102114

249156152147

14010410299

126123146163

373231225220

204156152148

165159187207

522320313307

284213208203

8 0258

3739NANA

8356NANA

50393733

58597790

16410810295

93756964

8383107122

273176168161

154119114107

123121151175

412261252243

234179171163

161155193223

580363352342

319246235225

10 02510

373952NA

876156NA

53413934

57597697

174117111100

99807668

8282105132

293193185171

165128122112

120119148188

444287277261

254194186171

158153190237

628400388369

344272261241

15 0251015

363851NANA

936963NANA

57474439NA

56577595NA

190136128116NA

11193867972

8080102128158

325225216201186

186149140131124

116115144182220

499337326308290

283224217203192

153148182228272

713473459438418

388314298284269

20 025101520

353750NANANA

967468NANANA

60504741NANA

54567393NANA

200148140129NANA

11899948680NA

7878100125155186

346248239223208192

201165158146136126

114113141177216254

537375363344325306

306248239224210196

149144178222264309

772528514491469448

428344334316301285

30 02510152030

343749NANANANA

998074NANANANA

635652NANANANA

53557291115NANA

211164157144131NANA

12711110698NANANA

767698122151181NA

372281271255239223NA

219183173168157NANA

110109136171208246NA

584429417397377357NA

334279271257242228NA

144139171213255298389

849610595570547524477

472392382367349333305

50 02510152030

333648NANANANA

998480NANANANA

6661NANANANANA

51537089112NANA

213181174160148NANA

133121117NANANANA

737394118145176NA

394318308292275257NA

230205198186174NANA

105104131162199236315

629495482461441420376

361312305292280267NA

138133164203244285373

928712696671646622573

515443435420405389NA

100 0251015203050

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

49516785132NANANA

214192186175162NANANA

NANANANANANANANA

697090113138168231NA

403351342324310295264NA

NANANANANANANANA

10098125153188224301NA

659563551532511487448NA

395373366354343NANANA

131125156191230270355540

991828813789764739685584

555508501486473458NANA

TABLE 5-9TYPE B DOUBLE-WALL GASVENT [NFPA 54: TABLE 13.1(b)]



WATER HEATERS





8 9 10 12


HEIGHTH(ft)

LATERALL(ft)

FAN NAT FAN NAT FAN NAT FAN NAT

Min Max Max Min Max Max Min Max Max Min Max Max

6 0246

211201237263

695423416409

369284277271

267251295327

894541533526

469368360352

371347409449

1,118673664656

569453443433

537498584638

1,639979971962

849648638627

8 0258

206197245280

777482470458

414321311300

258246305344

1,002617604591

536417404392

360339418470

1,257768754740

658513500486

521486598665

1,8521,1201,1041,089

967743730715

10 02510

202193241296

844531518497

449354344325

253242299363

1,093681667643

584456443423

351332409492

1,373849834808

718559544520

507475584688

2,0311,2421,2241,194

1,057848825788

15 0251015

195187231284334

966631616592568

523413400381367

244232287349404

1,259812795768742

681543526501484

336319392470540

1,5911,015997966937

838673657628601

488457562664750

2,3741,4911,4691,4331,399

1,237983963928894

20 025101520

190182224277325374

1,053708692666640616

573468457437419400

238227279339393448

1,379914896866838810

750611596570549526

326309381457526592

1,7511,1461,1261,0921,0601,028

927754734702677651

473443547646730808

2,6311,6891,6651,6261,5871,550

1,3461,0981,0741,0371,005973

30 02510152030

184175215265312360461

1,168823806777750723670

647533521501481461426

229219269327379433541

1,5421,0691,0491,017985955895

852698684662638615574

312296366440507570704

1,9711,3461,3241,2871,2511,2161,147

1,056863846821794768720

454424524620702780937

2,9961,9991,9711,9271,8841,8411,759

1,5451,3081,2831,2431,2051,1661,101

50 02510152030

176168204253299345442

1,292971953923894866809

704613602583562543502

220209257313363415521

1,7241,2731,2521,2171,1831,1501,086

948811795765736708649

295280347418481544674

2,2231,6151,5911,5511,5121,4731,399

1,1891,007991963934906848

428401496589668741892

3,4322,4262,3962,3472,2992,2512,159

1,8181,5091,4901,4551,4211,3871,318

100 0251015203050

166158194238281325418617

1,4041,1521,1341,1041,0751,046988866

765698688672656639NANA

207196240293342391491711

1,9001,5321,5111,4771,4431,4101,3431,205

1,033933921902884864824NA

273259322389447507631895

2,4791,9701,9451,9051,8651,8251,7471,591

1,3001,1681,1531,1331,1101,0871,041NA

395371460547618690834

1,138

3,9123,0212,9902,9382,8882,8382,7392,547

2,0421,8171,7961,7631,7301,6961,6271,489

TABLE 5-9TYPE B DOUBLE-WALL GASVENT [NFPA 54:Table 13.1(b)] (continued)



WATER HEATERS



APPLIANCEVENT CONNECTION: TYPE B DOUBLE-WALL CONNECTOR

TYPE B DOUBLE-WALL CONNECTOR DIAMETER – D (inch)TO BE USEDWITH CHIMNEY AREASWITHINTHE SIZE LIMITS AT BOTTOM

3 4 5 6 7


HEIGHTH(ft)

LATERALL(ft)



6 25

NANA

NANA

2825

NANA

NANA

5249

NANA

NANA

8682

NANA

NANA

130117

NANA

NANA

180165

8 258

NANANA

NANANA

292624

NANANA

NANANA

555248

NANANA

NANANA

938883

NANANA

NANANA

145134127

NANANA

NANANA

198183175

10 2510

NANANA

NANANA

312825

NANANA

NANANA

615750

NANANA

NANANA

1039687

NANANA

NANANA

162148139

NANANA

NANANA

221204191

15 251015

NANANANA

NANANANA

353528NA

NANANANA

NANANANA

67625548

NANANANA

NANANANA

1141079789

NANANANA

NANANANA

179164153141

53NANANA

475NANANA

250231216201

20 25101520

NANANANANA

NANANANANA

3836NANANA

NANANANANA

NANANANANA

746860NANA

NANANANANA

NANANANANA

1241161079783

NANANANANA

NANANANANA

201184172159148

5180NANANA

522503NANANA

274254237220206

30 2510152030

NANANANANANA

NANANANANANA

41NANANANANA

NANANANANANA

NANANANANANA

827667NANANA

NANANANANANA

NANANANANANA

13712811510791NA

NANANANANANA

NANANANANANA

216198184171159NA

4775NANANANA

581561NANANANA

303281263243227188

50 2510152030

NANANANANANA

NANANANANANA

NANANANANANA

NANANANANANA

NANANANANANA

92NANANANANA

NANANANANANA

NANANANANANA

161151138127NANA

NANANANANANA

NANANANANANA

251230215199185NA

NANANANANANA

NANANANANANA

351323304282264NA

Minimuminternalarea of

chimney(in.2)

12 19 28 38 50

Maximuminternalarea of

chimney(in.2)

Seven times the listed appliance categorized vent area, flue collar area, or draft hood outlet areas.


TABLE 5-10MASONRY CHIMNEY [NFPA 54-09:TABLE 13.1(c)]


WATER HEATERS


TABLE 5-10MASONRY CHIMNEY [NFPA 54-09: TABLE 13.1(c)] (continued)




TYPE B DOUBLE-WALL CONNECTOR DIAMETER – D (inch)TO BE USEDWITH CHIMNEY AREASWITHINTHE SIZE LIMITS AT BOTTOM

8 9 10 12


HEIGHTH(ft)

LATERALL(ft)



6 25

NANA

NANA

247231

NANA

NANA

320298

NANA

NANA

401376

NANA

NANA

581561

8 258

NANANA

NANANA

266247239

84NANA

590NANA

350328318

100149173

728711695

446423410

139201231

1,0241,007990

651640623

10 2510

68NANA

519NANA

298277263

82124155

655638610

388365347

98146182

810791762

491466444

136196240

1,1441,1241,093

724712668

15 251015

6499126NA

613594565NA

336313296281

77118148171

779759727698

441416394375

92139173198

968946912880

562533567485

127186229259

1,3761,3521,3151,280

841828777742

20 25101520

6195122NANA

678658627NANA

375350332314296

73113143165186

867845811780750

491463440418397

87133167191214

1,0831,0591,022987955

627597566541513

121179221251277

1,5481,5231,4821,4431,406

953933879840807

30 2510152030

5790115NANANA

762741709NANANA

421393373353332288

68106135156176NA

985962927893860NA

558526500476450416

81125158181203249

1,2401,2161,1761,1391,1031,035

717683648621592555

111169210239264318

1,7931,7661,7211,6791,6381,560

1,1121,0941,025981940877

50 2510152030

5183NANANANA

840819NANANANA

477445424400376327

6198126146165NA

1,1061,0831,0471,010977NA

633596567539511468

72116147170190233

1,4131,3871,3471,3071,2691,196

812774733702669623

99155195222246295

2,0802,0522,0061,9611,9161,832

1,2431,2251,1471,0991,050984


chimney(in.2)

63 78 95 132


chimney(in.2)



WATER HEATERS


TABLE 5-11MASONRY CHIMNEY [NFPA 54-09: TABLE 13.1(d)]




SINGLE-WALL METAL CONNECTOR DIAMETER – D (inch)TO BE USEDWITH CHIMNEY AREASWITHINTHE SIZE LIMITS AT BOTTOM

3 4 5 6 7


HEIGHTH(ft)

LATERALL(ft)



6 25

NANA

NANA

2825

NANA

NANA

5248

NANA

NANA

8681

NANA

NANA

130116

NANA

NANA

180164

8 258

NANANA

NANANA

292623

NANANA

NANANA

555147

NANANA

NANANA

938782

NANANA

NANANA

145133126

NANANA

NANANA

197182174

10 2510

NANANA

NANANA

312824

NANANA

NANANA

615649

NANANA

NANANA

1029586

NANANA

NANANA

161147137

NANANA

NANANA

220203189

15 251015

NANANANA

NANANANA

353227NA

NANANANA

NANANANA

67615446

NANANANA

NANANANA

1131069687

NANANANA

NANANANA

178163151138

166NANANA

473NANANA

249230214198

20 25101520

NANANANANA

NANANANANA

3835NANANA

NANANANANA

NANANANANA

736759NANA

NANANANANA

NANANANANA

1231151059580

NANANANANA

NANANANANA

200183170156144

163NANANANA

520NANANANA

273252235217202

30 2510152030

NANANANANANA

NANANANANANA

41NANANANANA

NANANANANANA

NANANANANANA

817566NANANA

NANANANANANA

NANANANANANA

13612711310588NA

NANANANANANA

NANANANANANA

215196182168155NA

158NANANANANA

578NANANANANA

302279260240223182

50 2510152030

NANANANANANA

NANANANANANA

NANANANANANA

NANANANANANA

NANANANANANA

91NANANANANA

NANANANANANA

NANANANANANA

160149136124NANA

NANANANANANA

NANANANANANA

250228212195180NA

NANANANANANA

NANANANANANA

350321301278258NA


chimney(in.2)

12 19 28 38 50


chimney(in.2)



WATER HEATERS


TABLE 5-11MASONRY CHIMNEY [NFPA 54-09:TABLE 13.1(d)] (continued)




SINGLE-WALL METAL CONNECTOR DIAMETER – D (inch)TO BE USEDWITH CHIMNEY AREASWITHINTHE SIZE LIMITS AT BOTTOM

8 9 10 12


HEIGHTH(ft)

LATERALL(ft)



6 25

NANA

NANA

247230

NANA

NANA

319297

NANA

NANA

400375

NANA

NANA

580560

8 258

NANANA

NANANA

265246237

NANANA

NANANA

349327317

382NANA

725NANA

445422408

549673747

1,0211,003985

650638621

10 2510

216NANA

518NANA

297276261

271334NA

654635NA

387364345

373459547

808789758

490465441

536657771

1,1421,1211,088

722710665

15 251015

211261NANA

611591NANA

335312294278

264325392452

776755722692

440414392372

362444531606

965942907873

560531504481

520637749841

1,3731,3481,3091,272

840825774738

20 25101520

206255312NANA

675655622NANA

374348330311292

258317382442NA

864842806773NA

490461437414392

252433517591663

1,0791,0551,016979944

625594562539510

508623733823911

1,5441,5181,4751,4341,394

950930875835800

30 2510152030

200245300NANANA

759737703NANANA

420391370349327281

249306370428NANA

982958920884NANA

556524496471445408

340417500572643NA

1,2371,2101,1681,1281,089NA

715680644615585544

489600708798883

1,055

1,7891,7601,7131,6681,6241,539

1,1101,0901,020975932865

50 2510152030

191NANANANANA

837NANANANANA

475442420395370318

238293355NANANA

1,1031,0781,038NANANA

631593562533504458

323398447546616NA

1,4081,3811,3371,2941,251NA

810770728695660610

463571674761844

1,009

2,0762,0441,9941,9451,8981,805

1,2401,2201,1401,0901,040970


chimney(in.2)

63 78 95 132


chimney(in.2)



WATER HEATERS

TABLE 5-12SINGLE-WALL METAL PIPE ORTYPE B ASBESTOS CEMENTVENT [NFPA 54:TABLE 13.1(e)]


APPLIANCETYPE: DRAFT HOOD-EQUIPPED

APPLIANCEVENT CONNECTION: CONNECTED DIRECTLYTO PIPE ORVENT

HEIGHTH(ft)

LATERALL(ft)

DIAMETER – D (inch)TO BE USEDWITH CHIMNEY AREASWITHINTHE SIZE LIMITS AT BOTTOM

3 4 5 6 7 8 10 12


MAXIMUM APPLIANCE INPUT RATING INTHOUSANDS OF BTU PER HOUR

6 025

393128

705551

1169488

170141128

232194177

312260242

500415390

750620600

8 02510

42322924

76615649

1261029586

185154141131

252210194180

340284264250

542451430406

815680648625

10 0251015

45353227NA

8467615446

1381111049484

202168153143130

279233215200186

372311289274258

606505480455432

912760724700666

15 025101520

49393530NANA

9172675850NA

1511221101039382

223186170158144132

312260240223207195

420350325308291273

684570540514488466

1,040865825795760726

20 025101520

53423832NANA

10180746555NA

16313612311510491

252210192178163149

342286264246228214

470392364345326306

770641610571550525

1,190990945910870832

30 02510152030

5644NANANANANA

108847868NANANA

18314813712511399NA

276230210196177163NA

384320296274258240192

529441410388366344295

878730694656625596540

1,3701,1401,0801,0501,000960890

50 02510152030

NANANANANANANA

12095NANANANANA

210171159146NANANA

310260234221200185NA

443370342318292276222

590492474456407384330

980820780730705670605

1,5501,2901,2301,1901,1301,0801,010



WATER HEATERS

TABLE 5-13EXTERIOR MASONRY CHIMNEY [NFPA 54: TABLE 13.1(f)]


APPLIANCETYPE: NAT


INTENDED USE: MINIMUM ALLOWABLE INPUT RATING OF SPACE-HEATING APPLIANCE INTHOUSANDS OF BTU PER HOUR

VENT HEIGHTH(ft)

INTERNAL AREA OF CHIMNEY (inch2)

12 19 28 38 50 63 78 113

681015203050

Local 99% winter design temperature: 37°F or greater000

NANANANA

0000

NANANA

0000

123NANA

0000

190NANA

0000

249NANA

0000

184393NA

00000

334NA

000000

579

681015203050

Local 99% winter design temperature: 27°F to 36°F000

NANANANA

0051NANANANA

688297NANANANA

116127141NANANANA

156167183233NANANA

180187201253307419NA

212214225274330445NA

266263265305362485763

681015203050

Local 99% winter design temperature: 17°F to 26°FNANANANANANANA

NANANANANANANA

NANANANANANANA

NANANANANANANA

NA197214NANANANA

215226245296352NANA

259264278331387507NA

349352358398457581NA

681015203050

Local 99% winter design temperature: 5°F to 16°FNANANANANANANA

NANANANANANANA

NANANANANANANA

NANANANANANANA

NANANANANANANA

NANA289NANANANA

NA312331393450NANA

416423430485547682972

681015203050

Local 99% winter design temperature: -10°F to 4°FNANANANANANANA

NANANANANANANA

NANANANANANANA

NANANANANANANA

NANANANANANANA

NANANANANANANA

NANANANANANANA

484494513586650805

1,003

Local 99% winter design temperature: -11°F or lowerNot recommended for any vent configurations

For SI units, 1 in. = 25.4 mm, 1 in.2 = 645 mm2, 1 ft. = 0.305 m, 1,000 Btu per hr = 0.293 kW, °C = (°F – 32)/1.8.Note: See Figure 5-13 for a map showing local 99 percent winter design temperatures in the United States.


WATER HEATERS

TABLE 5-14TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(a)]

NUMBER OF APPLIANCES: TWO OR MORE



VENT CONNECTOR CAPACITY

VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)

TYPE B DOUBLE-WALL VENT AND CONNECTOR DIAMETER – D (inch)

3 4 5 6 7

APPLIANCE INPUT RATING LIMITS INTHOUSANDS OF BTU PER HOUR



6 123

222324

374144

263135

353738

667581

465562

464849

106121132

728696

586062

164183199

104124139

777982

225253275

142168189

8 123

222324

404447

273236

353637

728087

485764

495153

114128139

7690101

646667

176195210

109129145

848688

243269290

148175198

10 123

222324

434750

283337

343637

788692

505967

495152

123136146

7893104

656769

189206220

113134150

899194

257282303

154182205

15 123

212224

505355

303540

333536

8996102

536371

474951

142153163

8399111

646668

220235248

120142160

889193

298320339

163193218

20 123

212223

545760

313742

333435

99105110

566674

464850

157167176

87104116

626466

246259271

125149168

868991

334354371

171202228

30 123

202122

626466

333944

313334

113118123

597079

454748

181190198

93110124

606264

288299309

134158178

838588

391408423

182215242

50 123

192122

717375

364348

303233

133137141

647686

434546

216223229

101119134

575961

349358366

145172194

788183

477490502

197234263

100 123

181920

828384

374450

283031

158161163

667989

404244

262267272

104123138

535557

442447452

150178200

737578

611619627

204242272

For SI units, 1 in. = 25.4 mm, 1 in.2 = 645 mm2, 1 ft. = 0.305 m, 1000 Btu per hr = 0.293 kW.

COMMONVENT CAPACITY

VENTHEIGHT

H(ft)

TYPE B DOUBLE-WALL COMMONVENT DIAMETER – D (inch)

4 5 6 7

COMBINED APPLIANCE INPUT RATING INTHOUSANDS OF BTU PER HOUR

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

92101110125136152167175

819097112123138153163

65737991102118134NA

140155169195215244279311

116129141164183210244277

103114124144160185214NA

204224243283314361421489

161178194228255297353421

147163178206229266310NA

309339367427475547641751

248275299352394459547658

200223242280310360423479


WATER HEATERS

TABLE 5-14TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(a)] (continued)

COMMONVENT CAPACITY

VENT HEIGHTH(ft)


8 9 10


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

404444477556621720854

1,025

314348377444499585706873

260290315365405470550625

547602649753842979

1,1641,408

434480522612688808977

1,215

335378405465523605705800

672740800924

1,0351,2091,4511,784

520577627733826975

1,1881,502

410465495565640740860975




APPLIANCEVENT CONNECTION: TYPE B DOUBLEWALL CONNECTOR


VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)


8 9 10


FAN NAT FAN NAT FAN NAT

Min Max Max Min Max Max Min Max Max

6 123

929597

296333363

185220248

109112114

376424463

237282317

128131134

466526575

289345386

8 123

100103105

320356384

194230258

118121123

408454492

248294330

138141143

507564612

303358402

10 123

106109111

341374402

200238268

125128131

436479515

257305342

146149152

542596642

314372417

15 123

110112115

389419445

214253286

134137140

493532565

273323365

162165167

609658700

333394444

20 123

107110113

436463486

224265300

131134137

552587618

285339383

158161164

681725764

347414466

30 123

103105108

512535555

238282317

125129132

649679706

305360405

151155158

802840874

372439494

50 123

97100103

627645661

257306343

120123126

797820842

330392441

144148151

9841,0141,043

403478538

100 123

919497

810822834

266316355

112115118

1,0381,0541,069

341405455

135139142

1,2851,3061,327

417494555


WATER HEATERS






VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)


12 14 16 18




6 246

174180NA

764897NA

496616NA

223230NA

1,0461,231NA

653827NA

281287NA

1,3711,617NA

8531,081NA

346352NA

1,7722,069NA

1,0801,370NA

8 246

186192198

822952

1,050

516644772

238244252

1,1261,3071,445

696884

1,072

298305313

1,4781,7191,902

9101,1501,390

365372380

1,9202,2112,434

1,1501,4601,770

10 246

196201207

870997

1,095

536664792

249256263

1,1951,3711,509

730924

1,118

311318325

1,5701,8041,989

9551,2051,455

379387395

2,0492,3322,556

1,2051,5351,865

15 246

214221228

9671,0851,181

568712856

272279286

1,3341,4991,632

7901,0061,222

336344351

1,7601,9782,157

1,0301,3201,610

408416424

2,3172,5792,796

1,3051,6652,025

20 246

223230237

1,0511,1621,253

596748900

291298307

1,4431,5971,726

8401,0641,288

357365373

1,9112,1162,287

1,0951,3951,695

430438450

2,5332,7782,984

1,3851,7652,145

30 246

216223231

1,2171,3161,400

632792952

286294303

1,6641,8021,920

9101,1601,410

367376384

2,1832,3662,524

1,1901,5101,830

461474485

2,8913,1103,299

1,5401,9202,340

50 246

206213221

1,4791,5611,631

689860

1,031

273281290

2,0232,1392,242

1,0071,2911,575

350359369

2,6592,8142,951

1,3151,6852,055

435447461

3,5483,7303,893

1,6652,1352,605

100 246

192200208

1,9231,9842,035

712888

1,064

254263272

2,6442,7312,811

1,0501,3461,642

326336346

3,4903,6063,714

1,3701,7602,150

402414426

4,7074,8424,968

1,7402,2202,700


COMMONVENT CAPACITY

VENTHEIGHT

H(ft)


12 14 16 18


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

900994

1,0761,2471,4051,6582,0242,569

696773841986

1,1161,3271,6402,131

588652712825916

1,0251,2801,670

1,2841,4231,5421,7942,0062,3732,9113,732

9901,1031,2001,4101,5881,8922,3473,076

815912995

1,1581,2901,5251,8632,450

1,7351,9272,0932,4402,7223,2203,9645,125

1,3361,4911,6251,9102,1472,5583,1834,202

1,0651,1901,3001,5101,6901,9902,4303,200

2,2532,5072,7273,1843,5614,1975,1846,749

1,7321,9362,1132,4842,7983,3264,1495,509

1,3451,5101,6451,9102,1402,5203,0754,050


WATER HEATERS






VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)


20 22 24




6 246

NANANA

NANANA

NANANA

NANANA

NANANA

NANANA

NANANA

NANANA

NANANA

8 246

NA471478

NA2,7373,018

NA1,8002,180

NA560568

NA3,3193,665

NA2,1802,640

NA662669

NA3,9574,373

NA2,5903,130

10 246

NA486494

NA2,8873,169

NA1,8902,290

NA581589

NA3,5023,849

NA2,2802,760

NA686694

NA4,1754,593

NA2,7103,270

15 246

NA523533

NA3,1973,470

NA2,0602,510

NA624634

NA3,8814,216

NA2,4903,030

NA734743

NA4,6315,035

NA2,9603,600

20 246

NA554567

NA3,4473,708

NA2,1802,650

NA661671

NA4,1904,511

NA2,6303,190

NA772785

NA5,0055,392

NA3,1303,790

30 246

NA619632

NA3,8404,080

NA2,3652,875

NA728741

NA4,8614,976

NA2,8603,480

NA847860

NA5,6065,961

NA3,4104,150

50 246

NA580594

NA4,6014,808

NA2,6333,208

NA709724

NA5,5695,826

NA3,1853,885

NA851867

NA6,6336,943

NA3,7904,620

100 246

NA523539

NA5,9826,143

NA2,7503,350

NA639654

NA7,2547,453

NA3,3304,070

NA769786

NA8,6508,892

NA3,9504,810

COMMONVENT CAPACITY

VENT HEIGHTH(ft)


20 22 24


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

2,8383,1623,4444,0264,5485,3036,5678,597

2,1802,4392,6653,1333,5524,1935,2406,986

1,6601,8602,0302,3602,6403,1103,8005,000

3,4883,8904,2414,9715,5736,5398,11610,681

2,6772,9983,2783,8624,3525,1576,4588,648

1,9702,2002,4002,7903,1203,6804,5005,920

4,2064,6955,1236,0166,7497,9409,83713,004

3,2263,6163,9574,6705,2616,2477,81310,499

2,3902,6802,9203,4003,8004,4805,4757,200



WATER HEATERS





VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)

SINGLE-WALL METALVENT CONNECTOR DIAMETER – D (inch)

3 4 5 6 7




6 123

NANANA

NANANA

263134

NANANA

NANANA

465562

NANA121

NANA131

718595

NA168175

NA182198

102123138

207215222

223251273

140167188

8 123

NANANA

NANANA

273235

NANANA

NANANA

485764

NA125130

NA126138

7589100

NA184191

NA193208

106127144

226234241

240266287

145173197

10 123

NANANA

NANANA

283336

NA8489

NA8591

505967

119124129

121134144

7791102

182189197

186203217

110132148

240248257

253278299

150183203

15 123

NANANA

NANANA

293439

798387

8794100

526270

116121127

138150160

8197109

177185193

214230243

116138157

238246255

291314333

158189215

20 123

495255

565962

303640

788287

97103107

546472

115120125

152163172

84101113

175182190

238252264

120144164

233243252

325346363

165197223

30 123

475154

606264

313742

778185

110115119

576776

112117122

175185193

89106120

169177185

278290300

129152172

226236244

380397412

175208235

50 123

464952

697172

344045

757983

128132136

607282

109114119

207215221

96113123

162170178

336345353

137164186

217226235

460473486

188223252

100 123

454851

798081

344146

717579

150153157

617385

104110114

249255260

98115129

153160168

424428433

140167190

205212222

585593603

192228256

COMMONVENT CAPACITY

VENTHEIGHT

H(ft)


4 5 6 7


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

NANANA121131145159166

788794108118132145153

6471768898113128NA

NANA163189208236268297

113126137159177202233263

99111120140156180208NA

200218237275305350406469

158173189221247286337398

144159174200223257296NA

304331357416463533622726

244269292343383446529633

196218236274302349410464

TABLE 5-15TYPE B DOUBLE-WALL VENT [NFPA 54:TABLE 13.2(b)]



WATER HEATERS





VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)


8 9 10




6 123

262271279

293331361

183219247

325334344

373422462

234281316

447458468

463524574

286344385

8 123

285293302

316353381

191228256

352360370

403450489

244292328

481492501

502560609

299355400

10 123

302311320

335369398

196235265

372381391

429473511

252302339

506517528

534589637

308368413

15 123

312321331

380411438

208248281

397407418

482522557

266317360

556568579

596646690

324387437

20 123

306317326

425453476

217259294

390400412

538574607

276331375

546558570

664709750

336403457

30 123

296307316

497521542

230274309

378389400

630662690

294349394

528541555

779819855

358425482

50 123

284294304

604623640

245293331

364376387

768793816

314375423

507520535

951983

1,013

384458518

100 123

269279289

774788801

249299339

345358368

9931,0111,027

321383431

476490506

1,2361,2591,280

393469527

COMMONVENT CAPACITY

VENTHEIGHT

H(ft)


8 9 10


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

398436467544606703833999

310342369434487570686846

257285309357395459535606

541592638738824958

1,1391,378

429473512599673790954

1,185

332373398456512593689780

665730787905

1,0131,1831,4181,741

515569617718808952

1,1571,459

407460487553626723838948

TABLE 5-15TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(b)] (continued)



WATER HEATERS





VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)

TYPE B DOUBLE-WALL VENT CONNECTOR DIAMETER – D (inch)

3 4 5 6 7




6 123

242627

334349

212834

394142

627992

405261

525355

106133155

678597

656769

194230262

101124143

878991

274324369

141173203

8 123

242627

394752

222934

394042

728797

415362

555759

117140159

698698

717375

213246269

105127145

949799

304350383

148179206

10 123

242627

425055

222935

384041

8093105

425463

555758

130153170

7187100

747678

232261284

108129148

101103106

324366397

153184209

15 123

242526

485559

233135

383941

93105115

445564

545657

154174189

7489102

727476

277299319

114134153

100103105

384419448

164192215

20 123

242526

525863

243135

373940

102114123

465665

535557

172190204

7791104

717375

313335353

119138157

98101104

437467493

173199222

30 123

242526

546064

253236

373840

111122131

485866

525456

192208221

8295107

697274

357376392

127145163

9699101

504531554

187209233

50 123

232426

515964

253236

363739

116127135

516169

515355

209225237

89102115

677072

405421435

143161180

929598

582604624

213235260

100 123

232425

465359

243135

353738

108120130

506068

495153

208224237

92105118

656769

428444458

155174193

889294

640660679

237260285

COMMONVENT CAPACITY

VENTHEIGHT

H(ft)

MINIMUM INTERNAL AREA OF MASONRY CHIMNEY FLUE (inch2)

12 19 28 38 50


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

NANANANANANANANA

748084NANANANANA

2528313641NANANA

NANANANANANANANA

119130138152NANANANA

4653566775NANANA

NANANANANANANANA

178193207233250270NANA

718290106122137NANA

NANANANANANANANA

257279299334368404NANA

103119131152172198NANA

NANANA523565615NANA

351384409467508564620NA

143163177212243278328348

TABLE 5-16MASONRY CHIMNEY [NFPA 54: TABLE 13.2(c)]



WATER HEATERS





VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)

TYPE B DOUBLE-WALL VENT CONNECTOR DIAMETER – D (inch)

8 9 10




6 123

104107109

370436491

201232270

124127129

479562633

253300349

145148151

599694795

319378439

8 123

113116119

414473517

210240276

134137139

539615672

267311358

156160163

682776848

335394452

10 123

120123126

444498540

216247281

142145147

582652705

277321366

165168171

739825893

348407463

15 123

125128131

511558597

229260292

153156159

658718760

297339382

184187190

824900960

375432486

20 123

123126129

584625661

239270301

150153156

752805851

312354396

180184187

9431,0111,067

397452505

30 123

119122125

680715746

255287317

145149152

883928968

337378418

175179182

1,1151,1711,220

432484535

50 123

115118121

798827854

294326357

140143147

1,0491,0851,118

392433474

168172176

1,3341,3791,421

506558611

100 123

109113116

907933956

334368399

134138141

1,2221,2531,282

454497540

161165169

1,5891,6261,661

596651705

COMMONVENT CAPACITY

VENTHEIGHT

H(ft)


63 78 113


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

NANA606682742816879NA

458501538611668747831NA

188218236283325381461499

NA724776874955

1,0621,165NA

582636686781858969

1,089NA

246278302365419496606669

1,0411,1441,2261,3741,5131,7021,9052,053

853937

1,0101,1561,2861,4731,6921,921

NA408454546648749922

1,058

TABLE 5-16MASONRY CHIMNEY [NFPA 54: TABLE 13.2(c)] (continued)



WATER HEATERS





VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)


3 4 5 6 7




6 123

NANANA

NANANA

212834

NANANA

NANANA

395261

NANA134

NANA153

668497

179186193

191227258

100123142

231239247

271321365

140172202

8 123

NANANA

NANANA

212834

NANANA

NANANA

405262

NA137143

NA139156

688598

195202210

208240264

103125145

250258266

298343376

146177205

10 123

NANANA

NANANA

222934

NANA97

NANA102

415362

130136143

151150166

708699

202210217

225255277

106128147

267276284

316358389

151181207

15 123

NANANA

NANANA

233034

NA9296

NA103112

435463

129135141

151170185

7388101

199207215

271295315

112132151

268277286

376411439

161189213

20 123

NANANA

NANANA

233035

879196

99111119

455564

128134140

167185199

7690103

197205213

303325343

117136154

265274282

425455481

169195219

30 123

NANANA

NANANA

243135

869195

108119127

475765

126132138

187203216

8093105

193201209

347366381

124142160

259269277

492518540

183205229

50 123

NANANA

NANANA

243135

858994

113123131

506068

124130136

204218231

87100112

188196205

392408422

139158176

252262271

567588607

208230255

100 123

NANANA

NANANA

233034

848893

104115124

495967

122127133

200215228

89102115

182190199

410425438

151169188

243253262

617636654

232254279

COMMONVENT CAPACITY

VENTHEIGHT

H(ft)


12 19 28 38 50


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

NANANANANANANANA

NANANANANANANANA

25283136NANANANA

NANANANANANANANA

118128136NANANANANA

4552566674NANANA

NANANANANANANANA

176190205230247NANANA

718189105120135NANA

NANANANANANANANA

255276295335362398NANA

102118129150170195NANA

NANANANANANANANA

348380405400503558612NA

142162175210240275325NA

TABLE 5-17MASONRY CHIMNEY [NFPA 54:TABLE 13.2(d)]



WATER HEATERS





VENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)


8 9 10




6 123

292301309

366432491

200231269

362373381

474557634

252299348

499509519

594696793

316376437

8 123

313323332

407465509

207238274

387397407

530607663

263309356

529540551

672766838

331391450

10 123

333343352

434489530

213244279

410420430

571640694

273317363

558569580

727813880

343403459

15 123

349359368

502548586

225256289

445456466

646706755

291334378

623634646

808884945

366424479

20 123

345355365

569610644

235266298

439450461

734787831

306348391

614627639

921986

1,042

387443496

30 123

338348358

665699729

250282312

430442452

864908946

330372412

600613626

1,0891,1451,193

421473524

50 123

328339349

778806831

287320351

417429440

1,0221,0581,090

383425466

582596610

1,3021,3461,386

492545597

100 123

315326337

875899921

328361392

402415427

1,1811,2101,238

444488529

560575589

1,5371,5701,604

580634687

COMMONVENT CAPACITY

VENTHEIGHT

H(ft)


63 78 113


FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

FAN+FAN

FAN+NAT

NAT+NAT

681015203050100

NANANA677765808NANA

455497532602661739821NA

187217234280321377456494

NANA771866947

1,0521,152NA

579633680772849957

1,076NA

245277300360415490600663

NA1,1361,2161,3591,4951,6821,8792,006

846928

1,0001,1391,2641,4471,6721,885

NA405450540640740910

1,046For SI units, 1 in. = 25.4 mm, 1 in.2 = 645 mm2, 1 ft. = 0.305 m, 1000 Btu per hr = 0.293 kW.

TABLE 5-17MASONRY CHIMNEY [NFPA 54: TABLE 13.2(d)] (continued)


WATER HEATERS

TABLE 5-18SINGLE-WALL METAL PIPE ORTYPE B ASBESTOS CEMENTVENT [NFPA 54: TABLE 13.2(e)]


APPLIANCETYPE: DRAFT HOOD-EQUIPMENT

APPLIANCEVENT CONNECTION: DIRECTTO PIPE ORVENT


TOTALVENTHEIGHT

H(ft)

CONNECTORRISE

R(ft)

VENT CONNECTOR DIAMETER – D (inch)

3 4 5 6 7 8


6-8 123

212834

405361

688698

102124147

146178204

205235275

15 123

233035

445664

7792102

117134155

179194216

240265298

30and up

123

253136

495868

8497107

129145164

190211232

270295321

COMMONVENT CAPACITY

TOTALVENTHEIGHT

H(ft)

COMMONVENT DIAMETER – D (inch)

4 5 6 7 8 10 12


681015203050

4855597180NANA

788995115129147NA

111128136168186215NA

155175190228260300360

205234250305340400490

320365395480550650810

NA505560690790940

1,190For SI units, 1 in. = 25.4 mm, 1 in.2 = 645 mm2, 1 ft. = 0.305 m, 1000 Btu per hr = 0.293 kW.


APPLIANCETYPE: NAT + NAT


INTENDED USE: COMBINED APPLIANCE MAXIMUM INPUT RATING INTHOUSANDS OF BTU PER HOUR

VENT HEIGHTH(ft)


12 19 28 38 50 63 78 113

681015203050100

252831NANANANANA

46535667NANANANA

718290106NANANANA



188218236283325NANANA

246278302365419496NANA

NA408454546648749922NA

TABLE 5-19EXTERIOR MASONRY CHIMNEY [NFPA 54:TABLE 13.2(f)]



WATER HEATERS


APPLIANCETYPE: NAT + NAT



VENT HEIGHTH(ft)


12 19 28 38 50 63 78 113


000NANANANANA

0000NANANANA

0000NANANANA

0000NANANANA

0000NANANANA

0000184393NANA

00000334NANA

NA00000579NA


000NANANANANA

0051NANANANANA

6882NANANANANANA

NANANANANANANANA

NANANANANANANANA

180187210253307NANANA

212214225274330445NANA

NA263265305362485763NA


NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NA264278331387NANANA

NA352358398457581862NA


NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NANANANANANANANA

NANA430485547682NANA

Local 99% winter design temperature: 4°F or lowerNot recommended for any vent configurations

TABLE 5-20EXTERIOR MASONRY CHIMNEY [NFPA 54: TABLE 13.2(g)]

For SI units, 1 in. = 25.4 mm, 1 in.2 = 645 mm2, 1 ft. = 0.305 m, 1000 Btu per hr = 0.293 kW, °C = (°F - 32)/1.8.Note: See Figure G.2.4 for a map showing local 99 percent winter design temperatures in the United States.


WATER HEATERS


APPLIANCETYPE: FAN + NAT


INTENDED USE: COMBINED APPLIANCE MAXIMUM INPUT RATING INTHOUSANDS OF BTU PER HOUR

VENT HEIGHTH(ft)


12 19 28 38 50 63 78 113

681015203050100

748084NANANANANA


178193207233250NANANA

257279299334368404NANA

351384409467508564NANA

458501538611668747831NA

582636686781858969

1,089NA

853937

1,0101,1561,2861,4731,6921,921

TABLE 5-21EXTERIOR MASONRY CHIMNEY [NFPA 54: TABLE 13.2(h)]



WATER HEATERS


APPLIANCETYPE: FAN + NAT



VENT HEIGHTH(ft)


12 19 28 38 50 63 78 113


000NANANANANA

0000NANANANA

0000123NANANA

0000190334NANA

0000249398NANA

0000184393714NA

00000334707NA

0000005791,600


000NANANANANA

0051111NANANANA

688297142187NANANA

116127141183230330NANA

156167183233284319NANA

180187210253307419672NA

212214225274330445705NA

2662632653053624857631,554


052NANANANANANA

557490NANANANANA

99111125167212NANANA

141154169212258362NANA

182197214263316429NANA

215226245296352470723NA

259264278331387507766NA

3493523583984575818621,669


NANANANANANANANA

7894111NANANANANA


166182198247293377NANA

214230250305360450NANA

252269289346408531797NA

301312331393450580853NA

4164234304855476829721,833

Local 99% winter design temperature: -10°F to 4°F681015203050100

NANANANANANANANA

NANANANANANANANA

145159175NANANANANA

196213231283333NANANA

249269292351408NANANA

296320339404468603NANA

349371397457528667955NA

4844945135866508051,003NA

Local 99% winter design temperature: -11°F or lowerNot recommended for any vent configurations

TABLE 5-22EXTERIOR MASONRY CHIMNEY [NFPA 54: TABLE 13.2(i)]

For SI units, 1 in. = 25.4 mm, 1 in.2 = 645 mm2, 1 ft. = 0.305 m, 1000 Btu per hr = 0.293 kW.Note: See Figure 5-13 for a map showing local 99 percent winter design temperatures in the United States.

PART II

This is originally from NFPA 54, which contains additionalreferences from the UPC.

Sizing of Venting Systems ServingAppliances Equipped withDraft Hoods, Category I Appliances, and Appliances Listedfor Use with Type B Vents


WATER HEATERS

G.1 Examples Using Single Appliance Venting Tables.See Figure G.1(a) through Figure G.1(n).

FIGURE G.1(a)TYPE B DOUBLE-WALLVENT SYSTEM SERVINGA SINGLE APPLIANCEWITH ATYPE B DOUBLE-WALLVENT.

FIGURE G.1(c) VENT SYSTEM SERVING A SINGLE APPLIANCEWITH A MASONRY CHIMNEY AND ATYPE B DOUBLE-WALL

VENT CONNECTOR.

FIGURE G.1(b) TYPE B DOUBLE-WALL VENT SYSTEMSERVING A SINGLE APPLIANCEWITH A SINGLE-WALL

METALVENT CONNECTOR.

FIGURE G.1(d) VENT SYSTEM SERVING A SINGLE APPLIANCEUSING A MASONRY CHIMNEY AND A SINGLE-WALL METAL

VENT CONNECTOR.


WATER HEATERS

FIGURE G.1(e) ASBESTOS CEMENTTYPE B OR SINGLE-WALLMETALVENT SYSTEM SERVING A SINGLE DRAFT-HOOD-

EQUIPPED APPLIANCE

FIGURE G.1(g) VENT SYSTEM SERVINGTWO OR MOREAPPLIANCESWITHTYPE B DOUBLE-WALL VENT AND

SINGLE-WALL METALVENT CONNECTORS.

FIGURE G.1(f) VENT SYSTEM SERVINGTWO OR MOREAPPLIANCESWITHTYPE B DOUBLE-WALL VENT ANDTYPE B

DOUBLE-WALL VENT CONNECTORS

FIGURE G.1(h) MASONRY CHIMNEY SERVING TWO ORMORE APPLIANCESWITH TYPE B DOUBLE-WALL VENT

CONNECTORS.


WATER HEATERS

FIGURE G.1(i) MASONRY CHIMNEY SERVINGTWO OR MOREAPPLIANCESWITH SINGLE-WALL VENT CONNECTORS.

FIGURE G.1(k) USE OF MANIFOLDED COMMONVENT CONNECTOR.

FIGURE G.1(j) ASBESTOS CEMENTTYPE B OR SINGLE-WALLMETALVENT SYSTEM SERVINGTWO OR MORE DRAFT-

HOOD-EQUIPPED APPLIANCES.

FIGURE G.1(l) USE OF OFFSET COMMONVENT.

G.1.1 Example 1: Single Draft-Hood-Equipped Appli-ance. An installer has a 120,000-Btu/h input appliance witha five (5) inch diameter draft hood outlet that needs to bevented into a ten (10) foot high Type B vent system. Whatsize vent should be used assuming (1) a five (5) foot lateralsingle-wall metal vent connector is used with two (2) 90 de-gree elbows or (2) a five (5) foot lateral single-wall metal ventconnector is used with three (3) 90 degree elbows in the ventsystem? (See Figure G.1.1).

SolutionTable 5-9 should be used to solve this problem because sin-gle-wall metal vent connectors are being used with a Type Bvent, as follows:(1) Read down the first column in Table 5-9 until the row

associated with a ten (10) foot height and five (5) footlateral is found. Read across this row until a vent capac-ity exceeding 120,000 Btu/h is located in the shadedcolumns labeled NAT Max for draft-hood-equipped ap-pliances. In this case, a five (5) inch diameter vent has acapacity of 122,000 Btu/h and can be used for this ap-plication.

(2) If three (3) 90 degree elbows are used in the vent system,the maximum vent capacity listed in the tables must bereduced by 10 percent (See NFPA 54:13.1.3). This im-plies that the five (5) inch diameter vent has an adjustedcapacity of only 110,000 Btu/h. In this case, the vent sys-tem must be increased to six (6) inches in diameter. Seethe following calculations:

122,000 x 0.90 = 110,000 for five (5) inch ventFrom Table 5-10, select six (6) inch vent.186,000 x 0.90 = 167,000

This figure is exceeding the required 120,000.Therefore, use a six (6) inch vent and connector wherethree (3) elbows are used.

G.1.2. Example 2: Single Fan-Assisted Appliance. An in-staller has an 80,000 Btu/h input fan-assisted appliance thatmust be installed using ten (10) feet of lateral connector at-tached to a thirty (30) foot high Type B vent. Two (2) 90 de-gree elbows are needed for the installation. Can a single-wallmetal vent connector be used for this application? See FigureG.1.2.

SolutionTable 5-9 refers to the use of single-wall metal vent connec-tors with Type B vent. In the first column find the row associ-ated with a thirty (30) foot height and a ten (10) foot lateral.Read across this row, looking at the FAN Min and FAN Maxcolumns, to find that a three (3) inch diameter single-wall metalvent connector is not recommended. Moving to the next larger


WATER HEATERS

FIGURE G.1(m) MULTISTORY GASVENT DESIGN PROCEDUREFOR EACH SEGMENT OF SYSTEM

FIGURE G.1(n) PRINCIPLES OF DESIGN OF MULTISTORYVENTS USINGVENT CONNECTOR AND COMMONVENT

DESIGNTABLES.

size single-wall connector (four (4) inch), we find that a four (4)inch diameter single-wall metal connector has a recommendedmaximum vent capacity of 144,000 Btu/h. The 80,000 Btu/hfan-assisted appliance is outside this range, so the conclusionis that a single-wall metal connector could be used to vent theappliance. Table 5-9 shows the acceptable range of vent ca-pacities for a four (4) inch vent with five (5) feet of lateral tobe between 72,000 Btu/h and 157,000 Btu/h.

If the appliance cannot be moved closer to the verticalvent, then a Type B vent could be used as the connector ma-terial. In this case, Table 5-8 shows that, for a thirty (30) foothigh vent with ten (10) feet of lateral, the acceptable range ofvent capacities for a four (4) inch diameter vent attached to afan-assisted appliance is between 37,000 Btu/h and 150,000Btu/h.

G.1.3. Example 3: Interpolating Between Table Values.Aninstaller has an 80,000 Btu/h input appliance with a four (4)inch diameter draft hood outlet that needs to be vented into atwelve (12) foot high Type B vent. The vent connector has a5-foot lateral length and is also Type B vent. Can this appli-ance be vented using a four (4) inch diameter vent?

SolutionTable 5-8 is used in the case of an all Type B Vent system.However, since there is no entry in Table 5-8 for a height oftwelve (12) feet, interpolation must be used. Read down thefour (4) inch diameter NATMax column to the row associatedwith a ten (10) foot height and five (5) foot lateral to find thecapacity value of 77,000 Btu/h. Read further down to the fif-teen (15) foot height, five (5) foot lateral row to find the ca-pacity value of 87,000 Btu/h. The difference between thefifteen (15) foot height capacity value and the ten (10) footheight capacity value is 10,000 Btu/h. The capacity for a ventsystem with a twelve (12) foot height is equal to the capacityfor a ten (10) foot height plus two-fifths (2⁄5) of the differencebetween the ten (10) foot and fifteen (15) foot height values,or 77,000 + 2⁄5 x 10,000 = 81,000 Btu/h. Therefore, a four (4)inch diameter vent can be used in the installation.

G.2 Examples Using Common Venting Tables.G.2.1 Example 4: Common Venting Two Draft-Hood-Equipped Appliances.A 35,000-Btu/h water heater is to becommon vented with a 150,000 Btu/h furnace, using a com-mon vent with a total height of thirty (30) feet. The connec-tor rise is two (2) feet for the water heater with a horizontallength of four (4) feet. The connector rise for the furnace isthree (3) feet with a horizontal length of eight (8) feet.Assumesingle-wall metal connectors will be used with Type B vent.What size connectors and combined vent should be used inthis installation?See Figure G.2.1.


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FIGURE G.1.1 SINGLE DRAFT HOOD-EQUIPPED APPLIANCE– EXAMPLE 1

FIGURE G.1.2 SINGLE FAN-ASSISTED APPLIANCE – EXAMPLE 2

FIGURE G.2.1 COMMONVENTINGTWODRAFT HOOD-EQUIPPEDAPPLIANCES – EXAMPLE 4

SolutionTable 5-15 should be used to size single-wall metal vent

connectors attached to Type B vertical vents. In the vent con-nector capacity portion of Table 5-15, find the row associatedwith a thirty (30) foot vent height. For a two (2) foot rise onthe vent connector for the water heater, read the shadedcolumns for draft-hood-equipped appliances to find that athree (3) inch diameter vent connector has a capacity of37,000 Btu/h. Therefore, a three (3) inch single-wall metalvent connector can be used with the water heater. For a draft-hood-equipped furnace with a three (3) foot rise, read acrossthe appropriate row to find that a five (5) inch diameter ventconnector has a maximum capacity of 120,000 Btu/h (whichis too small for the furnace), and a six (6) inch diameter ventconnector has a maximum vent capacity of 172,000 Btu/h.Therefore, a six (6) inch diameter vent connector should beused with the 150,000 Btu/h furnace. Since both vent con-nector horizontal lengths are less than the maximum lengthslisted in Table 5-8, the table values can be used without ad-justments.

In the common vent capacity portion of Table 5-15, findthe row associated with a thirty (30) foot vent height and readover to the NAT + NAT portion of the six (6) inch diametercolumn to find a maximum combined capacity of 257,000Btu/h. Since the two (2) appliances total only 185,000 Btu/h,a six (6) inch common vent can be used.

G.2.2 Example 5(a): Common Venting a Draft-Hood-EquippedWater Heater with a Fan-Assisted Furnace intoa Type B Vent. In this case, a 35,000-Btu/h input draft-hood-equipped water heater with a four (4) inch diameter draft hoodoutlet, two (2) feet of connector rise, and four (4) feet of hor-izontal length is to be common vented with a 100,000 Btu/hfan-assisted furnace with a four (4) inch diameter flue collar,three (3) feet of connector rise, and six (6) feet of horizontallength. The common vent consists of a thirty (30) foot heightof Type B vent.What are the recommended vent diameters foreach connector and the common vent? The installer would liketo use a single-wall metal vent connector. See Figure G.2.2.

Solution (See Table 5-15)Water Heater Vent Connector Diameter. Since the water

heater vent connector horizontal length of four (4) feet is lessthan the maximum value listed in Table 5-15, the ventingtable values can be used without adjustment. Using the VentConnector Capacity portion of Table 5-15, read down theTotal Vent Height (H) column to thirty (30) feet and readacross the two (2) feet Connector Rise (R) row to the firstBtu/h rating in the NAT Max column that is equal to or ex-ceeding the water heater input rating. The table shows that athree (3) inch vent connector has a maximum input rating of37,000 Btu/h. Although this rating is exceeding the waterheater input rating, a three (3) inch vent connector is prohib-ited by Section 511.1.1(5). A four (4) inch vent connector hasa maximum input rating of 67,000 Btu/h and is equal to thedraft hood outlet diameter. A four (4) inch vent connector is


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NOMINALLINER SIZE(inch)

INSIDE DIMEN-SIONS OFLINER(inch)

INSIDE DIAMETER OREQUIVALENT DIAME-

TER(inch)

EQUIVALENTAREA(inch2)

4 x 8 21⁄2 x 61⁄2 4.0 12.25.0 19.66.0 28.37.0 38.3

8 x 8 63⁄4 x 63⁄4 7.4 42.78.0 50.3

8 x 12 61⁄2 x 101⁄2 9.0 63.610.0 78.5

12 x 12 93⁄4 x 93⁄4 10.4 83.311.0 95.0

12 x 16 91⁄2 x 131⁄2 11.8 107.512.0 113.014.0 153.9

16 x 16 131⁄4 x 131⁄4 14.5 162.915.0 176.7

16 x 20 13 x 17 16.2 206.118.0 254.4

20 x 20 163⁄4 x 163⁄4 18.2 260.220.0 314.1

20 x 24 161⁄2 x 201⁄2 20.1 314.222.0 380.1

24 x 24 201⁄4 x 201⁄4 22.1 380.124.0 452.3

24 x 28 201⁄4 x 241⁄4 24.1 456.228 x 28 241⁄4 x 241⁄4 26.4 543.3

27.0 572.530 x 30 251⁄2 x 251⁄2 27.9 607.030 x 36 251⁄2 x 311⁄2 30.9 749.9

33.0 855.336 x 36 311⁄2 x 311⁄2 34.4 929.4

36.0 1017.9

TABLE G.2.3MASONRY CHIMNEY LINER DIMENSIONSWITH CIRCULAR

EQUIVALENTS

For SI units, 1 in. = 25.4 mm, 1 in.2 = 645 mm2.Note:When liner sizes differ dimensionally from those shown in this table,equivalent diameters can be determined from published tables for squareand rectangular ducts of equivalent carrying capacity or by other engi-neering methods.

FIGURE G.2.2 COMMONVENTING A DRAFT HOOD-EQUIPPEDWATER HEATERWITH A FAN-ASSISTED FURNACE INTO ATYPE B DOUBLE-WALL COMMONVENT – EXAMPLE 5(a).

selected. Since the water heater is equipped with a draft hood,there are no minimum input rating restrictions.

Furnace Vent Connector Diameter. Using the Vent Con-nector Capacity portion of Table 5-15, read down the TotalVent Height (H) column to thirty (30) feet and across the three(3) foot Connector Rise (R) row. Since the furnace has a fan-assisted combustion system, find the first FAN Max columnwith a Btu/h rating exceeding the furnace input rating. Thefour (4) inch vent connector has a maximum input rating of119,000 Btu/h and a minimum input rating of 85,000 Btu/h.

The 100,000-Btu/h furnace in this example falls withinthis range, so a four (4) inch connector is adequate. Since thefurnace vent connector horizontal length of six (6) feet is lessthan the maximum value listed in Table 5-8, the venting tablevalues can be used without adjustment. If the furnace had aninput rating of 80,000 Btu/h, then a Type B vent connectorwould be needed in order to meet the minimum capacity limit(See Table 5-14).

Common Vent Diameter. The total input to the commonvent is 135,000 Btu/h. Using the CommonVent Capacity por-tion of Table 5-15, read down the Vent Height (H) column tothirty (30) feet and across this row to find the smallest vent di-ameter in the FAN + NAT column that has a Btu/h ratingequal to or exceeding 135,000 Btu/h. The four (4) inch com-mon vent has a capacity of 132,000 Btu/h and the five (5)inch common vent has a capacity of 202,000 Btu/h. There-fore, the five (5) inch common vent should be used in this ex-ample.Summary: In this example, the installer can use a four (4) inchdiameter, single-wall metal vent connector for the waterheater and a four (4) inch diameter, single-wall metal ventconnector for the furnace. The common vent should be a five(5) inch diameter Type B vent.

G.2.3 Example 5(b): Common Venting into an Interior Ma-sonry Chimney. In this case, the water heater and fan-assistedfurnace of Example 5(a) are to be common-vented into a clay-tile-lined masonry chimney with a thirty (30) foot height. Thechimney is not exposed to the outdoors below the roof line.The internal dimensions of the clay tile liner are nominallyeight (8) inches x twelve (12) inches.Assuming the same ventconnector heights, laterals, and materials found in example5(a), what are the recommended vent connector diameters,and is this an acceptable installation?

SolutionTable 5-17 is used to size common venting installations in-volving single-wall connectors into masonry chimneys.

Water Heater Vent Connector Diameter. Using Table 5-17, Vent Connector Capacity, read down the Vent Height (H)column to thirty (30) feet, and read across the two (2) footConnector Rise (R) row to the first Btu/h rating in the NATMax column that is equal to or exceeding the water heaterinput rating. The table shows that a three (3) inch vent con-

nector has a maximum input of only 31,000 Btu/h, while afour (4) inch vent connector has a maximum input of 57,000Btu/h. A four (4) inch vent connector must therefore be used.

Furnace Vent Connector Diameter. Using the Vent Con-nector Capacity portion of Table 5-17, read down the totalVent Height (H) column to thirty (30) feet and across the three(3) feet Connector Rise (R) row. Because the furnace has afan-assisted combustion system, find the first FAN Max col-umn with a Btu/h rating exceeding the furnace input rating.The four (4) inch vent connector has a maximum input ratingof 127,000 Btu/h and a minimum input rating of 95,000Btu/h. The 100,000 Btu/h furnace in this example falls withinthis range, so a four (4) inch connector is adequate.

Masonry Chimney. From Table G.2.3, the equivalent areafor a nominal liner size of eight (8) inches x twelve (12)inches is sixty-three and six-tenths (63.6) of a square inch.Using Table 5-17, Common Vent Capacity, read down theFAN + NAT column under the Minimum Internal Area ofChimney value of sixty-three (63) to the row for thirty (30)foot height to find a capacity value of 739,000 Btu/h. Thecombined input rating of the furnace and water heater,135,000 Btu/h, is less than the table value so this is an ac-ceptable installation.Section 511.1.8 requires the common vent area to not exceedseven (7) times the smallest listed appliance categorized ventarea, flue collar area, or draft hood outlet area. Both appli-ances in this installation have four (4) inch diameter outlets.From Table G.2.3, the equivalent area for an inside diameterof four (4) inches is twelve and two-tenths (12.2) of a squareinch. Seven (7) times twelve and two-tenths (12.2) equalseighty-five and four-tenths (85.4), which is exceeding sixty-three and six-tenths (63.6), so this configuration is accept-able.G.2.4 Example 5(c): Common Venting into an ExteriorMasonry Chimney. In this case, the water heater and fan-as-sisted furnace of Examples 5(a) and 5(b) are to be common-vented into an exterior masonry chimney. The chimneyheight, clay-tile-liner dimensions, and vent connector heightsand laterals are the same as in Example 5(b). This system isbeing installed in Charlotte, North Carolina. Does this exte-rior masonry chimney need to be relined? If so, what corru-gated metallic liner size is recommended? What ventconnector diameters are recommended? See Table G.2.3 andFigure 5-14.

SolutionAccording to 511.2.17, Type B vent connectors are re-

quired to be used with exterior masonry chimneys. Use Table5-21 and Table 5-22 to size FAN+NAT common venting in-stallations involving Type-B double-wall connectors into ex-terior masonry chimneys.

The local 99 percent winter design temperature needed touse Table 5-21 and Table 5-22 can be found in the ASHRAEHandbook – Fundamentals. For Charlotte, North carolina,this design temperature is 19°F (-7.22°C).

Chimney Liner Requirement.As in Example 5(b), use thesixty-three (63) square inch column of Table 5-21 to the thirty


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(30) foot height row to find that the combined appliance max-imum input is 747,000 Btu/h. The combined input rating ofthe appliance in this installation, 135,000 Btu/h, is less thanthe maximum value, so this criterion is satisfied. Table 5-22,at a 19°F (-7.22°C) design temperature, and at the same ventheight and internal area used earlier, shows that the minimumallowable input rating of a space-heating appliance is 470,000Btu/h. The furnace input rating of 100,000 Btu/h is less thanthis minimum value. So this criterion is not satisfied, and analternative venting design needs to be used, such as a Type Bvent shown in Example 5(a) or a listed chimney liner systemshown in the rest of the example.

According to Section 511.2.19, Table 5-9 or Tables 5-14or 5-15 are used for sizing corrugated metallic liners in ma-sonry chimneys, with the maximum common vent capacitiesreduced by 20 percent. This example will be continued as-suming Type B vent connectors.

Water Heater Vent Connector Diameter. Using Table 5-14 Connector Capacity, read down the total Vent Height (H)column to thirty (30) feet, and read across the two (2) footConnector Rise (R) row to the first Btu/hour rating in the NATMax column that is equal to or exceeding the water heaterinput rating. The table shows that a three (3) inch vent con-nector has a maximum capacity of 39,000 Btu/h. Althoughthis rating is exceeding the water heater input rating, a three(3) inch vent connector is prohibited by Section 511.1.6. Afour (4) inch vent connector has a maximum input rating of70,000 Btu/h and is equal to the draft hood outlet diameter. Afour (4) inch vent connector is selected.

Furnace Vent Connector Diameter. Using Table 5-14,Vent Connector Capacity, read down the total Vent Height (H)column to thirty (30) feet, and read across the three (3) footConnector Rise (R) row to the first Btu/h rating in the FANMAX column that is equal to or exceeding the furnace inputrating. The 100,000 Btu/h furnace in this example falls withinthis range, so a four (4) inch connector is adequate.

Chimney Liner Diameter. The total input to the commonvent is 135,000 Btu/h. Using the CommonVent Capacity por-tion of Table 5-14, read down the total Vent Height (H) col-umn to thirty (30) feet and across this row to find the smallestvent diameter in the FAN + NAT column that has a Btu/h rat-ing exceeding 135,000 Btu/h. The four (4) inch common venthas a capacity of 138,000 Btu/h. Reducing the maximum ca-pacity by 20 percent (See 13.2.19) results in a maximum ca-pacity for a four (4) inch corrugated liner of 110,000 Btu/h,less than the total input of 135,000 Btu/h. So a larger liner isneeded. The five (5) inch common vent capacity listed inTable 5-14 is 210,000 Btu/h, and after reducing by 20 percentis 168,000 Btu/h. Therefore, a five (5) inch corrugated metalliner should be used in this example.

Single Wall Connectors.Once it has been established thatrelining the chimney is necessary, Type B double-wall ventconnectors are not specifically required. This example couldbe redone using Table 5-15 for single-wall vent connectors.For this case, the vent connector and liner diameters would bethe same as found for Type B double-wall connectors.

The following is originally from NFPA54, National Fuel GasCode, which contains additional reference.

Example of Combination of Indoor and Outdoor Com-bustion and Ventilation Opening Design.

J.1 Example of Combination Indoor and Outdoor Com-bustion Air Opening. Determine the required combinationof indoor and outdoor combustion air opening sizes for thefollowing appliance installation example.

Example Installation:Afan-assisted furnace and a draft-hood-equipped water heater with the following inputs are lo-cated in a fifteen (15) foot x thirty (30) foot basement with aneight (8) foot ceiling. No additional indoor spaces can be usedto help meet the appliance combustion air needs.Fan-Assisted Furnace Input: 100,000 Btu/h

Draft-Hood-Equipped Water Heater Input: 40,000 Btu/h

Solution(1) Determine the total available room volume: Equipment

room volume:Fifteen (15) feet x thirty (30) feet with an eight (8) footceiling = thirty-six-hundred (3,600) cubic feet

(2) Determine the total required volume: The standard methodto determine combustion air will be used to calculate therequired volume.The combined input for the appliances located in thebasement is calculated as follows:100,000 Btu/h +40,000 Btu/h = 140,000 Btu/hThe Standard Method requires that the required volumebe determined based on fifty (50) cubic feet per 1,000Btu/hour.Using TableA.9.3.2.1, the required volume for a 140,000Btu/h water heater is seven-thousand (7,000) cubic feet.

Conclusion: Indoor volume is insufficient to supply com-bustion air since the total of thirty-six-hundred (3,600)cubic feet does not meet the required volume of seven-thousand (7,000) cubic feet. Therefore, additional com-bustion air must be provided from the outdoors.

(3) Determine ratio of the available volume to the requiredvolume:

(4) Determine the reduction factor to be used to reduce thefull outdoor air opening size to the minimum required basedon ratio of indoor spaces:

1.00 – 0.51 (from Step 3) = 0.49


WATER HEATERS

3,600 ft.3 = 0.517,000 ft.3

(5) Determine the single outdoor combustion air openingsize as if combustion air is to come from outdoors. In thisexample, the combustion air opening directly communi-cates with the outdoors.

(6) Determine the minimum outdoor combustion air open-ing area:

Outdoor opening area = 0.49(from Step 4) x 47 in.2= 23 in.2

Section 507.3 requires the minimum dimension of the airopening shall be not less than three (3) inches.


WATER HEATERS

APPLIANCE INPUT (Btu/h) REQUIREDVOLUME (ft.3)5000 25010 000 50015 000 75020 000 100025 000 125030 000 150035 000 175040 000 200045 000 225050 000 250055 000 275060 000 300065 000 325070 000 350075 000 375080 000 400085 000 425090 000 450095 000 4750100 000 5000105 000 5250110 000 5500115 000 5750120 000 6000125 000 6250130 000 6500135 000 6750140 000 7000145 000 7250150 000 7500160 000 8000170 000 8500180 000 9000190 000 9500200 000 10 000210 000 10 500220 000 11 000230 000 11 500240 000 12 000250 000 12 500260 000 13 000270 000 13 500280 000 14 000290 000 14 500300 000 15 000

TABLE A.9.3.2.1STANDARD METHODVOLUME, ALL APPLIANCES

507.4.1 See Figure 5-8 • 507.4.1(1) See Figure 5-9 and Figure 5-10 •507.4.1(2) See Figure 5-11 • 507.4.2 See Figure 5-12

140,000 Btu/h = 47 in.23,000 Btu/in.2

CALIFORNIA 2010 - IAPMO Group California Plumbing Code/Chapter 05.pdf · 507.3 Indoor Opening Size...

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