VENTING AND COMBUSTION AIR Roberts Mechanical Equipment Co. .

VENTING AND VENTING AND COMBUSTION AIRCOMBUSTION AIRRoberts Mechanical Equipment Co.Roberts Mechanical Equipment Co.

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ANSI CATEGORIESANSI CATEGORIES

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ANSI Categories ANSI Categories will tell you a great will tell you a great deal about the deal about the boiler and the boiler and the application.application.

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Understand the TableUnderstand the Table

Left side indicates a Left side indicates a negative pressure.negative pressure.

Right Side indicates Right Side indicates a positive pressure.a positive pressure.II

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IV

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Understand the TableUnderstand the Table

Top indicates non-Top indicates non-condensing condensing appliance (85% or appliance (85% or less).less).

Bottom indicates Bottom indicates condensing condensing appliances (86% or appliances (86% or more).more).

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Examples (negative)Examples (negative)

Atmospheric Atmospheric

Some fan assistedSome fan assisted

Masonry Chimney Masonry Chimney

B-Vent materialB-Vent materialII

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Examples (Positive)Examples (Positive)

Forced Draft Forced Draft

Side wall ventedSide wall vented

In line fan In line fan

UL Pressure stack or UL Pressure stack or welded steelwelded steel

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Condensing / Non-CondensingCondensing / Non-CondensingEffect of Inlet Water Temperature to Boiler Effect of Inlet Water Temperature to Boiler EfficiencyEfficiency

natural gas = 1050 Btu/ftnatural gas = 1050 Btu/ft

inlet water temperatureinlet water temperature

boile

r effi

cien

cy, %

boile

r effi

cien

cy, %

1801804040 1301308080

100100

8686

9494

condensing boilercondensing boiler non-condensing boilernon-condensing boiler

dew pointdew point

8080

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IWWW.ROBERTSMECH.COM WWW.ROBERTSMECH.COM



Lining A Masonry Lining A Masonry Chimney (Cat. I)Chimney (Cat. I)

Atmospheric – Clay Atmospheric – Clay Tile Liner Tile Liner

Fan Assisted – Clay Fan Assisted – Clay Tile Liner (Interior) Tile Liner (Interior) Metal Liner (Exterior)Metal Liner (Exterior)

Exception: Clay tile liner can be used with exterior chimney if an Atmospheric appliance is connected to the same chimney

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Reference: ANSI Z223.1-2002 10.4.1 and 13.1.9, NFPA211 4-2.2




Lining A Masonry Lining A Masonry Chimney (Category III)Chimney (Category III)

Forced Draft – Welded Forced Draft – Welded Steel, Pressure Stack, Steel, Pressure Stack, or Inner Liner of or Inner Liner of Pressure Rated StackPressure Rated Stack

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Lining A Masonry Lining A Masonry Chimney (Category II)Chimney (Category II)

Fan Assisted– (85%Fan Assisted– (85%+ Combustion + Combustion Efficiency) AL29-4CEfficiency) AL29-4C

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Lining A Masonry Lining A Masonry Chimney (Category IV)Chimney (Category IV)

Fully Condensing – Fully Condensing – AL29-4CAL29-4C

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Safe Venting by CodeSafe Venting by Code

• Horizontal distances

• Large stack area

• Self venting connector rise

• Fan Min capacities

• Different type of appliances

• Existing masonry chimneys

• Location of draft inducer

National Fuel Gas CodeNFPA54 * IAS (A.G.A.) * ANSI Z 223.1




Common ViolationsCommon Violations

10.6.1.4 The total horizontal distance of a vent plus the horizontal vent connector serving draft hood-equipped appliances shall not be greater than 75 % of the vertical height of the vent.

Table 13.1 and 13.2 The total horizontal length of the vent plus the vent connector for a single Category I appliance is: 100% of the height (vent 6 – 30 ft high); 30 ft (vent 31 – 50 ft high); 50% of the height (vent 51 – 100 ft high)

(NFPA 54) Z223.1-2002 (Venting of Equipment)

Heightof

Vent

Not Greater than 75%of the Vertical Height





13.2.2 The maximum vent connector horizontal length shall be 18 in./in of connector diameter.

13.2.4 The length of the common vent manifold shall not exceed 18 in./in. of common vent diameter.

13.2.5 The horizontal length of the common vent offset shall not exceed 18 in./in. of common vent diameter.

(NFPA 54) Z223.1-2002 13.2 (Sizing of Venting Systems)

Diameter

18 inches per inch

3" 4" 5" 6" 7" 8" 9" 10" 12" 14" 16" 18" 20" 22" 24"4.5' 6' 7.5' 9' 10.5'12' 13.5'15' 18' 21' 24' 27' 30' 33' 36'

3" 4" 5" 6" 7" 8" 9" 10" 12" 14" 16" 18" 20" 22" 24"4.5' 6' 7.5' 9' 10.5'12' 13.5'15' 18' 21' 24' 27' 30' 33' 36'





(NFPA 54) Z223 Sizing Tables

1’ Min. (3”-10” diameter)2’ Min. (12”- 18” diameter)4’ Min. (20” and above)





13.2.17 Where two or more appliances are connected to a vertical vent or chimney, the flow area of the largest section of vertical or chimney shall not exceed seven times the smallest listed appliance categorized vent areas, flue collar area, or draft hood outlet area unless designed in accordance with approved engineering methods.

(NFPA 54) Z223.1-2002 13.2.17 (Sizing of Venting Systems)

Outlet Diameter

Not Greater than 7 Timesthe Smallest Outlet Area

3" 4" 5" 6" 7" 8" 9" 10" 12" 14" 16"7" 10" 12" 14" 18" 22" 22" 26" 30" 36" 42"

3" 4" 5" 6" 7" 8" 9" 10" 12" 14" 16"7" 10" 12" 14" 18" 22" 22" 26" 30" 36" 42"





10.10.4.2 Vent connectors serving Category I appliances shall not be connected into any portion of mechanical draft systems operating under positive static pressure, such as those serving Category III or Category IV appliances.

(NFPA 54) Z223.1-2002 10.10.4.2 (Venting of Equipment)





10.5.4.3 Masonry chimneys shall be built and installed in accordance with NFPA 211.

4-2.2 Masonry chimneys shall be lined….Cat II, III and IV gas appliances - special gas vents listed for installation within masonry chimneys.

(NFPA 54) Z223.1-2002 10.5.4.3(NFPA 211) 4-2.2





10.3.3 Forced draft systems and all portions of induced draft systems under positive pressure during operation shall be designed and installed so as to prevent leakage of flue or vent gases into a building.

10.3.4 Vent connectors serving equipment vented by natural draft shall not be connected into any portion of mechanical draft systems operating under positive pressure.

(NFPA 54) Z223.1- 2002 10.3 (Mechanical Draft Systems)




Resolving Codes using Resolving Codes using Mechanical Draft Mechanical Draft SystemSystem

503.6.9.3 Mechanical draft. Chimney venting systems using mechanical draft shall be sized in accordance with approved engineering methods.

10.5.3.1 Size of Chimneys. Chimney venting systems using mechanical draft shall be sized in accordance with approved engineering methods.

International Fuel Gas International Fuel Gas CodeCode - Section 503 - Section 503 (Venting of Equipment)(Venting of Equipment)

International Fuel Gas International Fuel Gas CodeCode - Section 503 - Section 503 (Venting of Equipment)(Venting of Equipment)

Z223.1- 2002 Z223.1- 2002 Standard for Venting Standard for Venting of Equipmentof Equipment

Z223.1- 2002 Z223.1- 2002 Standard for Venting Standard for Venting of Equipmentof Equipment




Mechanical Draft Mechanical Draft SystemSystem(Check List)(Check List)

System should be UL listed (as a designed system).

System must Monitor proper draft at all times.

System must interlock, alarm and lock out appliances.

System must be supplied with engineering (Acceptable Engineering Method) specific to installed appliances.

System should modulate to match today’s efficient appliances.

System performance should be guaranteed.




Vent Category ReviewVent Category Review

CategorCategoryy

CharacteristicCharacteristic TypeType DraftDraft VentVent

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IVIV

Non-

Condensing

Negative

pressure

Natural draft

appliance and

fan assisted

< 86 % efficient

Draft hood:

Negative

Fan-assist: - 0.02

to - 0.08

B-Vent

Condensing

Negative pressure

Fan assisted

appliance

> 86 % efficient

Fan-assist:

- 0.02 to -

0.08

AL29-4C

Non-Condensing

Positive pressure

Forced draft /

Direct Vent

< 86 % efficient

Positive

Forced Draft(Pressure stack) Direct Vent (AL29)

Condensing

Positive pressure

Fan assisted/

Pulse

Positive AL29-4C




Combustion AirCombustion Air



Combustion AirCombustion AirCodeCode

8.3.3.2 One Permanent Opening Method: One permanent 8.3.3.2 One Permanent Opening Method: One permanent opening, commencing within 12 in. of the top of the opening, commencing within 12 in. of the top of the enclosure, shall be provided. The opening shall enclosure, shall be provided. The opening shall directly communicate with the outdoors or shall directly communicate with the outdoors or shall communicate through a vertical or horizontal duct communicate through a vertical or horizontal duct to the outdoors or spaces that freely communicate to the outdoors or spaces that freely communicate with the outdoors and shall have a minimum free with the outdoors and shall have a minimum free area of the following:area of the following:

1 in.²/3000 Btu of the total input rating of all equipment 1 in.²/3000 Btu of the total input rating of all equipment located in the enclosure, and not less than the sum located in the enclosure, and not less than the sum of the areas of all vent connectors in the space.of the areas of all vent connectors in the space.

8.3.3.2 One Permanent Opening Method: One permanent 8.3.3.2 One Permanent Opening Method: One permanent opening, commencing within 12 in. of the top of the opening, commencing within 12 in. of the top of the enclosure, shall be provided. The opening shall enclosure, shall be provided. The opening shall directly communicate with the outdoors or shall directly communicate with the outdoors or shall communicate through a vertical or horizontal duct communicate through a vertical or horizontal duct to the outdoors or spaces that freely communicate to the outdoors or spaces that freely communicate with the outdoors and shall have a minimum free with the outdoors and shall have a minimum free area of the following:area of the following:

1 in.²/3000 Btu of the total input rating of all equipment 1 in.²/3000 Btu of the total input rating of all equipment located in the enclosure, and not less than the sum located in the enclosure, and not less than the sum of the areas of all vent connectors in the space.of the areas of all vent connectors in the space.

Z223.1-2002 8.3.3 Outdoor Combustion AirZ223.1-2002 8.3.3 Outdoor Combustion Air.



Sizing Combustion Air Sizing Combustion Air Louvers (Gravity)Louvers (Gravity)

Louver(s) Sizing:1 sq.in./4000 Btu per louver1 sq.in./4000 Btu per louver 4000 MBH = 1000 in24000 MBH = 1000 in2 of of freefree area per louver. area per louver.

Typical louver has 30-60% free area.

Depending on louver design Depending on louver design actual louver size will be:actual louver size will be:

Using 45% free area Using 45% free area louverslouvers = Two 5’ x 4’ = Two 5’ x 4’ louverslouvers

2000 MBH

2000 MBH

Tip: Check with the Louver Manufacturer for accurate ‘free Tip: Check with the Louver Manufacturer for accurate ‘free space’ than watch equal products in the submittals.space’ than watch equal products in the submittals.



Combustion Code Combustion Code Summery.Summery.

NFPA 54gas

NFPA 31oil

BOCAall

SBCCIgas & oil

SBCCIsolid

Minimum No. openings required 2 2 2 2 2

Outdoor opening, sq. in./Btuh 1/4000 1/4000 1/4000 1/4000 2/1000

Vertical ducts, sq. in./Btuh 1/4000 1/4000 1/4000 1/4000 -

Horizontal ducts, sq. in./Btuh 1/2000 1/2000 1/2000 1/2000 -

Ducts same as opening yes yes - yes -

Minimum duct dimension, inches 3 3 3 3 3

Louver & grill free area opening opening - - opening

Free area allowance, wood* 20-25% 20-25% 25% - -

Free area allowance, metal* 60-75% 60-75% 75% - -

Damper interlocked yes yes yes - -

*use manufacturer's free area rating when available.



Below Grade Mechanical Below Grade Mechanical RoomsRooms

Total fuel input rate of all fuel-burning devices located in the boiler room considered.

The Btu rate per hour of all boilers at maximum burning rate, plus other devices such as water heaters, are used to size air openings.

Outside air openings sizing must be done based on its free area. (Protective mesh must be no smaller than 0.25 inch to minimize dirt build-up or obstruction.



Direct Connect Direct Connect Combustion AirCombustion Air

Best with Fan Assisted Appliances.

Roof or Single side.Careful combining

Combustion air intakes.

Watch Horizontal lengths (fitting equal 10’).

FREEZE PROTECTION

Tip:Tip: Freeze protection should be proven damper system operating in the specific boiler sequence.

Allows combining inlet also prevent freezing without power.



Combustion AirCombustion AirCodeCode

8.3.6 Mechanical Combustion Air Supply. Where all combustion 8.3.6 Mechanical Combustion Air Supply. Where all combustion air is provided by a mechanical air supply system, the air is provided by a mechanical air supply system, the combustion air shall be supplied from outdoors at the combustion air shall be supplied from outdoors at the minimum rate of 0.35 ft³/min per 1000 Btu/hr for all minimum rate of 0.35 ft³/min per 1000 Btu/hr for all appliances located within the space.appliances located within the space.

8.3.6.1 Where exhaust fans are installed, additional air shall be 8.3.6.1 Where exhaust fans are installed, additional air shall be provided to replace the exhausted air.provided to replace the exhausted air.

8.3.6.2 Each of the appliances served shall be interlocked to the 8.3.6.2 Each of the appliances served shall be interlocked to the mechanical air supply system to prevent main burner mechanical air supply system to prevent main burner operation where the mechanical air supply system is not in operation where the mechanical air supply system is not in operation.operation.

8.3.6 Mechanical Combustion Air Supply. Where all combustion 8.3.6 Mechanical Combustion Air Supply. Where all combustion air is provided by a mechanical air supply system, the air is provided by a mechanical air supply system, the combustion air shall be supplied from outdoors at the combustion air shall be supplied from outdoors at the minimum rate of 0.35 ft³/min per 1000 Btu/hr for all minimum rate of 0.35 ft³/min per 1000 Btu/hr for all appliances located within the space.appliances located within the space.

8.3.6.1 Where exhaust fans are installed, additional air shall be 8.3.6.1 Where exhaust fans are installed, additional air shall be provided to replace the exhausted air.provided to replace the exhausted air.

8.3.6.2 Each of the appliances served shall be interlocked to the 8.3.6.2 Each of the appliances served shall be interlocked to the mechanical air supply system to prevent main burner mechanical air supply system to prevent main burner operation where the mechanical air supply system is not in operation where the mechanical air supply system is not in operation.operation.

Z223.1-2002Z223.1-2002



Mechanical Mechanical Combustion AirCombustion Air

Guaranteed to provide proper combustion air.

Small opening / more aesthetic.

Solves Code Issues

Tip:Tip: Multiple water heaters or boilers running high efficiency firing rates warrant a modulating

combustion air system.



Sizing Mechanical Sizing Mechanical Combustion AirCombustion Air

Louver Sizing:Engineered using ASHRAE

Chimney Design Equation.

Flue Gas Volume corrected for temperature = 1,400 cfm of combustion air

1400 cfm/500 fpm = 2.8 ft2 of louver free area

Using a 45% free area louver = One 3’ x 2’ louver

Tip:Tip: Be sure to consider any mechanical exhaust in the boiler. Fan must keep up with all ventilation as well.

2000

MBH

2000

MBH



The Barometric The Barometric DamperDamper

NORMAL OPERATION

Barometric Damper is weighted to open and ‘break’ draft by mixing a % of room air.

The chimney is drawing at a specific rate, but now draws from the water heater/boiler and room.

Typical draft for negative commercial appliances is -.02 to -.08.

Tip:Tip: Use a barometric damper on stacks over 25’ or 30’ as long as the appliance is category I or II (negative).



The Barometric The Barometric DamperDamper

NEGATIVE MECH ROOM:

Room goes negative.

Barometric is pulled into the room.

The barometric becomes a source of make up air for the room.

Problem is, this make up air is deadly.

Tip:Tip: Pay close attention to the combustion air in a room. Look for sources of problems such as old leaky returns.



Thank You!Thank You!

More Information / Additional Training:More Information / Additional Training: Roberts Mechanical EquipmentRoberts Mechanical EquipmentP: 216-587-0005P: 216-587-0005F: 216-587-0008F: 216-587-0008

Or visit our industry leading web site at:Or visit our industry leading web site at:www.robertsmech.com

More Information / Additional Training:More Information / Additional Training: Roberts Mechanical EquipmentRoberts Mechanical EquipmentP: 216-587-0005P: 216-587-0005F: 216-587-0008F: 216-587-0008

Or visit our industry leading web site at:Or visit our industry leading web site at:www.robertsmech.com

Written by/Property of: Grant RobertsWritten by/Property of: Grant Roberts


http://www.robertsmech.com/

http://www.robertsmech.com/


VENTING AND COMBUSTION AIR Roberts Mechanical Equipment Co. .

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Transcript of VENTING AND COMBUSTION AIR Roberts Mechanical Equipment Co. .