Expansion Tank Sizing Calculation (Hydronic System)

17
Expansion Tank EasyCalc eil software 2008 1 Expansion Tank EasyCalc HYDRONIC SYSTEM EXPANSION TANK CALCULATION (c) 2000 ASHRAE Handbook, HVAC Systems & Equipment, Hydronic Heating & Cooling System Desig Equations for Sizing Expansion Tanks: Date Prep. 3/11/2022 (Sometimes called a plain steel tank) Open Tanks with air/water interface: (i.e., A tank open to the atmosphere & must be located above the highest point in the system) For Diaphragm Tanks: (Flexible membrane between the air & the water. Another configuration is the bladder tank) R Data Entry Expansion Tank Calculation Where: Site Altitude-Elevation (m)0 Closed Open Diaphragm = 39 Temp T2 Hi 144 = volume of water in system, gallons 3000 3000 3000 3000 = lower temperature, °F 40 40 40 40 = higher temperature, °F 220 220 220 220 = atm.pres.psia (14.696 psia at sea le 14.696 14.696 not reqrd. not reqrd. = pressure at lower temperature, psia 4.0 4.0 not reqrd. 4.0 = pressure at higher temperature, psia 39.7 39.7 not reqrd. 39.7 = 0.01602 0.01602 0.01602 0.01602 = 0.01677 0.01677 0.01677 0.01677 = 180 180 180 180 = linear coef.of thermal expansion, in/ 6.50E-06 6.50E-06 6.50E-06 6.50E-06 ` System Equipment Data (Sys. Components) Vol. of Water in Sys Hydronic Components Water Content Capacity Liters Gallons Piping Distribution System 11356.25 3000.00 Fan Coils 0.0057 Liters - - per lps of airflow Total Lps Air Handling Units 1.2 Liters - - per Ton of Refrigeration Total Tons Chillers 0.7 Liters - - per Ton of Refrigeration Total Tons Boilers 1.9 Liters - - per Kw Total Kw Radiators 2 Liters - - Total 11356.25 3000.00 Plus safety factor for other components, fittings etc. (%) 0.0% - - MODA GDMW, Engineering Design Branch, Developed by: Edgar I. Lim, EasyCalc Software ® EasyCalc Software Email Address For Closed Tanks with air/water interface: Vt vol.of expansion tank, gal (Closed, Ope Vs t1 t2 Pa P1 P2 v1 specific vol.of water at lower temp., v2 specific vol.of water at higher temp. (t2−t1),°F, temperature differential (α equals to 6.5 ×10 −6 in/in-°F for steel or 9.5 ×10 −6 in/in-°F for copper) Water Volume in Hydronic System Components (Cooling or Heatin per m 2 of Heat Surface Tot. m 2 of H.S

description

EXCEL CALCULATION OF HYDRONIC SYSTEM EXPANSION TANK in accordance with ASHRAE standards

Transcript of Expansion Tank Sizing Calculation (Hydronic System)

Expansion Tank EasyCalc

eil software 2008 1 Expansion Tank EasyCalc

HYDRONIC SYSTEM EXPANSION TANK CALCULATION(c) 2000 ASHRAE Handbook, HVAC Systems & Equipment, Hydronic Heating & Cooling System Design, Chap.12

Equations for Sizing Expansion Tanks:

Job no.: Date Prep. 4/8/2023

Equation (12) (Sometimes called a plain steel tank)

● Open Tanks with air/water interface: (i.e., A tank open to the atmosphere & must be Equation (13)

located above the highest point in the system)

● For Diaphragm Tanks: (Flexible membrane between the air & the water. Equation (14) Another configuration is the bladder tank)

REQUIRED DATA FOR CALCULATIONS Data Entry Expansion Tank Calculation

Where: Site Altitude-Elevation (m)► 0 Closed Open Diaphragm

= ► 39 Temp T2 Hi 144

= volume of water in system, gallons 3000 3000 3000 3000

= lower temperature, °F 40 40 40 40

= higher temperature, °F 220 220 220 220

= atm.pres.psia (14.696 psia at sea level) 14.696 14.696 not reqrd. not reqrd.

= pressure at lower temperature, psia 4.0 4.0 not reqrd. 4.0

= pressure at higher temperature, psia 39.7 39.7 not reqrd. 39.7

= 0.01602 0.01602 0.01602 0.01602

= 0.01677 0.01677 0.01677 0.01677

Δt = 180 180 180 180

α = linear coef.of thermal expansion, in/in-°F 6.50E-06 6.50E-06 6.50E-06 6.50E-06

`

System Equipment Data (Sys. Components) Vol. of Water in System Hydronic Components Water Content Capacity Liters Gallons

Piping Distribution System 11356.25 3000.00

Fan Coils 0.0057 Liters - -per lps of airflow Total Lps

Air Handling Units 1.2 Liters - -per Ton of Refrigeration Total Tons

Chillers 0.7 Liters - -per Ton of Refrigeration Total Tons

Boilers 1.9 Liters - -per Kw Total Kw

Radiators 2 Liters - -

Total 11356.25 3000.00

Plus safety factor for other components, fittings etc. (%) 0.0% - -

Grand Total Volume of Water in System11356 3000

MODA GDMW, Engineering Design Branch, Developed by: Edgar I. Lim, EasyCalc Software®

EasyCalc Software Email Address

● For Closed Tanks with air/water interface:

Vt vol.of expansion tank, gal (Closed, Open, Diaph)

Vs

t1

t2

Pa

P1

P2

v1 specific vol.of water at lower temp., ft3/lb

v2 specific vol.of water at higher temp. ft3/lb

(t2−t1),°F, temperature differential

(α equals to 6.5 ×10−6 in/in-°F for steel or 9.5 ×10−6 in/in-°F for copper)

Water Volume in Hydronic System Components (Cooling or Heating)

per m2 of Heat Surface Tot. m2 of H.S

F11
Edgar I. Lim: Open Tanks are to be used only for low temperature system with maximum system temperature of 200oF. Open tanks are not to be used for medium & high temp. system.
G20
Edgar I. Lim: Provide data entries on yellow cells only. For help, see respective cell comments & other notes provided below this sheet. Entries for pressures at lower & high temperatures shall be absolute pressures. The local atmospheric pressure must be added to the gauge pressure to arrive at the true absolute pressure of the site.
H20
Edgar I. Lim: An expansion tank is required in the water loop to allow for the thermal expansion of the water. Expansion tanks can be open type, closed type with air-water interface or diaphragm type. Tank location will influence the type. Open tanks must be located above the highest point in the system (for example, the penthouse). Air water interface and diaphragm type tanks can be located anywhere in the system. Generally, the lower the pressure in the tank, the smaller the tank needs to be. Tank size can be minimized by locating it higher in the system.
F21
Edgar I. Lim: Site altitude entry (in meters) is required only for Closed Expansion Tank calculation. Enter 0 for sea level atmospheric pressure (14.696 psia) Note: Calculation is disabled at altitude in excess of 8,850 m. Mount Everest is the highest mountain in the world at 8,850 m (29,035 ft).
H21
Edgar I. Lim: A closed tank, contains a captured volume of compressed air and water, with an air water interface (sometimes called a plain steel tank). Note: Current design practice normally employs diaphragm tanks. (c) 2000 ASHRAE Handbook, HVAC Systems and Equipment, Chapter 12
I21
Edgar I. Lim: Open Tanks are to be used only for low temp system with max. system temp of 200oF. Program does not accept temp for opent tanks above 200oF. Open tanks are not to be used for medium & high temp. system. Note: Current design practice normally employs diaphragm tanks.
J21
Edgar I. Lim: A diaphragm tank, in which a flexible membrane is inserted between the air and the water (another configuration of a diaphragm tank is the bladder tank). In the plain steel tank and the open tank, gases can enter the system water through the interface and can adversely affect system performance. Thus, current design practice normally employs diaphragm tanks. (c) 2000 ASHRAE Handbook, HVAC Systems and Equipment, Chapter 12
H22
Edgar I. Lim: Notes: 1) If the specific vol.of water at lower temp.(v1) equals the specific vol.of water at higher temp.(v2) then no water volume expansion occurs in the system thus no expansion tank is required. 2) Closed expansion tank capacity available commercially (from Armstrong) Minimum - 15 gal. Maximum - 525 gal. See the complete list of commercially available tank sizes below this sheet.
I22
Edgar I. Lim: Notes: 1) If the specific vol.of water at lower temp.(v1) equals the specific vol.of water at higher temp.(v2) then no water volume expansion occurs in the system thus no expansion tank is required. 2) Open expansion tanks are not available commercially from Armstrong. These open expansion tanks are usually fabricated by project contractors.
J22
Edgar I. Lim: Notes: 1) If the specific vol.of water at lower temp.(v1) equals the specific vol.of water at higher temp.(v2) then no water volume expansion occurs in the system thus no expansion tank is required. 2) Diaphragm/Bladder expansion tank capacity available commercially (from Armstrong). See the complete list of commercially available tank sizes below this sheet. Minimum - 7.8 gal. Maximum - 1056 gal. Diaphragm from - 7.8 to 211 gallons Bladder from - 53 to 1056 gallons ( Bladder tank is another configuration of a diaphragm tank and tank sizing equation is the same for both tank configuration)
F23
Edgar I. Lim: No entry required here. See calculation tabulation below where the required entries are to be made. Note: The volume of water in system shall include all the water in the system. All interconnected components of the system such us the pipe works, boilers, heat exchangers, AHU etc. shall be accounted for the calculation of water volume in the system.
F24
Edgar I. Lim: USE DROPDOWN LIST TO SELECT TEMPERATURE HEATING SYSTEM: t1 = Raw water initial or entering temperature usually 40–50°F Temperature at Fill Condition. The size of expansion tank must be based on temp. changes during initial system fill. For example, in low temp. hydronic heating system when boiler and piping system need to be initially filled during winter time, the city water temp. could be as low as 40°F, which must be heated to 200°F. In this case, the piping system will experience a large temp. difference and the system expansion tank must be sized to handle this large temp. increase. COOLING SYSTEM: t1 = Normally operates with a design supply water temp. of 40 to 55°F, usually 44 or 45°F min. - 40 oF, max. - 100 oF (Armstrong limits)
F25
Edgar I. Lim: HEATING SYSTEM: t2 = Design supply water temp.of hot water system (varies as per design). See notes. COOLING SYSTEM: t2 = The ambient temp. of site usually 115 °F for KSA hot areas. See Design Weather Data. min. - 50 oF, max. - 240 oF (Armstrong limits)
F26
Edgar I. Lim: Enter elevation input above to generate atmospheric pressure entry on this cell at said site altitude. This input is required only for closed tank sizing. Atmospheric pressure at sea level (0 altitude) is 14.696 psia. Atmospheric pressures at different altitude is based from 1997 ASHRAE Handbook, Fundamentals, Chapter 6 Table 1 Standard Atmospheric Data (See copy of table on this Excel worksheet)
I26
Edgar I. Lim: Atm.pres.psia data (Pa) & pressures for lower & higher temp (P1 & P2) are not required for Open tank calculation.
J26
Edgar I. Lim: Atm.pres.psia data (Pa) not required for Diaphragm tank calculation.
F27
Edgar I. Lim: See notes from ASHRAE System Fill Pressure/Minimum System Pressure (Psia) (System minimum pressure) The lower pressure is usually selected to hold a positive pressure at the highest point in the system (usually about 10 psig or 24.696 psia). (Min. pres. cannot be less than the site altitude atm. pressure. (c) 2000 ASHRAE Handbook, HVAC Systems and Equipment, Chapter 12 Other Estimates: System Fill Pressure/Minimum System Pressure Estimate: Static plus adequate positive pressure at top, at tank location. Height of System +5 to 10 Psig OR 5–10 Psig, whichever is greater. min. - 17.2 psia, max. - 104.7 psia (Armstrong limits)
I27
Edgar I. Lim: Atm.pres.psia data (Pa) & pressures for lower & higher temp (P1 & P2) are not required for Open tank calculation.
B28
Edgar I. Lim: Common Boiler Design Pressures in psig. Add 14.696 to get absolute pressure at sea level. 1. 15 Psig 2. 30 Psig 3. 60 Psig 4. 125 Psig 5. 150 Psig 6. 200 Psig 7. 250 Psig 8. 300 Psig 9. 350 Psig
F28
Edgar I. Lim: See notes from ASHRAE System Operating Pressure/Maximum Operating Pressure (Psia) The higher pressure is normally set by the maximum pressure allowable at the location of the safety relief valve(s) without opening them. Or relief valve pressure setting less 10%, at tank location. (c) 2000 ASHRAE Handbook, HVAC Systems and Equipment, Chapter 12 min. - up to 139.7 psia (Armstrong limits) HEATING SYSTEM: P2 = See notes from ASHRAE COOLING SYSTEM: P2 = Usually equivalent to pump TDH + 14.7 , psia
I28
Edgar I. Lim: Atm.pres.psia data (Pa) & pressures for lower & higher temp (P1 & P2) are not required for Open tank calculation.
F29
Edgar I. Lim: Program generated entry from ASHRAE Fundamentals Table 3 Thermodynamic Properties of Water at Saturation Note: The specific vol. of water from 33oF to 51oF is 0.01602 ft3/lb
F30
Edgar I. Lim: Program generated entry taken from ASHRAE Fundamentals Table 3 Thermodynamic Properties of Water at Saturation Note: ASHRAE TABLE thermodynamic Properties limited up to 300oF temp. Properties from 300 to 470 oF were taken from other sources. The specific vol. of water from 33oF to 51oF is 0.01602 ft3/lb
F31
Edgar I. Lim: No entry required here.
F32
Edgar I. Lim: Use the dropdown list to select the linear coef.of thermal expansion for steel or copper (in/in-°F) STEEL = 6.5 ×10−6 in/in-°F COPPER = 9.5 ×10−6 in/in-°F
J37
Edgar I. Lim: Note: The volume of water in system shall include all the water in the system. All interconnected components of the system such us the pipe works, boilers, heat exchangers, AHU etc. shall be accounted for the calculation of water volume in the system.
F38
Edgar I. Lim: Design factors of the water content of the respective system components.
H38
Edgar I. Lim: Cumulative sum of equipment capacities connected to the operation of the hydronic system.
G39
Edgar I. Lim: See tabulated calculation below.
H39
Edgar I. Lim: See tabulated calculation below.
G40
Edgar I. Lim: Value taken from Design Consultant Firm engineering values. This value may be changed as appropriate. Original value: 0.0057 liters per lps of FCU airflows
G42
Edgar I. Lim: Value taken from Design Consultant Firm design engineering values. This value may be changed as appropriate. Original value: 1.2 liters per ton of refrigeration
C44
Edgar I. Lim: Chilled water (CW) system. This hydronic cooling system normally operates with a design supply water temperature of 40 to 55°F, usually 44 or 45°F, and at a pressure of up to 120 psi. Antifreeze or brine solutions may be used for applications (usually process applications) that require temperatures below 40°F or for coil freeze protection. (c) 2000 ASHRAE Handbook, HVAC Systems and Equipment, Chapter 12
G44
Edgar I. Lim: Value taken from Design Consultant Firm design engineering values. This value may be changed as appropriate. Original value: 0.7 liters per ton of refrigeration
C46
Edgar I. Lim: Working Pressure and Temperature With few exceptions, all boilers are constructed to meet ASME Boiler and Pressure Vessel Code, Section IV Low-pressure boilers are constructed for maximum working pressures of 15 psig steam and up to 160 psig hot water. Hot water boilers are limited to 250°F operating temperature. Medium- and high-pressure boilers are designed to operate above 15 psig steam or above 160 psig or 250°F for water boilers. Water boilers are available in standard sizes from 50,000 to over 100,000,000 Btu/h, many of which are in the low-pressure class and are used for space heating. Some water boilers may be equipped with either internal or external heat exchangers to supply domestic (service) hot water. (c) 2000 ASHRAE Handbook, HVAC Systems and Equipment, Chapter 27
G46
Edgar I. Lim: Value taken from Design Consultant Firm design engineering values. This value may be changed as appropriate. Original value: 1.9 liters per boiler kw.
C48
Edgar I. Lim: RADIATORS, convectors, and baseboard and finned-tube units are heat-distributing devices used in steam and low-temperature water heating systems. They supply heat through a combination of radiation and convection and maintain the desired air temperature in a space without the use of fans. (c) 2000 ASHRAE Handbook, HVAC Systems and Equipment, Chapter 32
G48
Edgar I. Lim: Value taken from Design Consultant Firm design engineering values. This value may be changed as appropriate. Original value: 5.1 liters per m2 of heat surface.
H51
Edgar I. Lim: Enter in percentage & not decimal. Negative entries allowed to enable lowering of the total volume to a desired value.

Expansion Tank EasyCalc

eil software 2008 2 Expansion Tank EasyCalc

Grand Total Volume of Water in SystemLiters Gallons

Water Volume Calculation in System Distribution Pipe Works

Nom. Pipe Size Pipe Length Liters per Water Vol. Water Vol.

Inch mm meters Lineal meter Liters Gallons

1/2" 15 4.25 196 0.196 0.8 0.2

3/4" 20 344 0.344 - -

1" 25 557.6 0.558 - -

1-1/4" 32 965 0.965 - -

1-1/2" 40 19 1313 1.313 24.9 6.6

2" 50 333 2165 2.165 720.9 190.5

2-1/2" 65 3089 3.089 - -

3" 75 4769 4.769 - -

4" 100 8213 8.213 - -

5" 125 822 12907 12.907 10609.5 2802.7

6" 150 18639 18.639 - -

8" 200 32280 32.280 - -

10" 250 50870 50.870 - -

12" 300 72190 72.190 - -

14" 350 87290 87.290 - -

16" 400 114000 114.000 - -

18" 450 144300 144.300 - -

20" 500 179400 179.400 - -

Total water volume in distribution pipe works11356.25 3000.00

Liters GallonsNOTES:(c) 2000 ASHRAE Handbook, HVAC Systems & Equipment, Hydronic Heating & Cooling System Design, Chap.12

Low-temperature water (LTW) system. Medium-temperature water (MTW) system. Max. allowable working pres. for low-pres. boilers is Operates at temperatures between 250 & 350°F, 160 psig,with a max. temp. limitation of 250°F. with pressures not exceeding 160 psi.

Usual max. working pres. for boilers for LTW Usual design supply temperature is approx. 250 to 325°F,

systems is 30 psi with a usual pres.rating of 150 psi for boilers & equipment.

High-temperature water (HTW) system. Chilled water (CW) system. Operates at temp. over 350°F & usual pressures Normally operates w/ design supply water temp.of 40 to of about 300 psi. 55°F, usually 44 or 45°F, & at a pres. of up to 120 psi.

Max. design supply water temp.is usually about 400°F,

w/ a pres.rating for boilers & equipt. of about 300 psi

The connected piping in hydronic systems is subject to expansion & contraction due to changes in system temp. especially during

initial system fill. Expansion tanks (or compression tanks) are required to protect against thermal expansion of the piping system

due to temperature rise. During initial fill the piping system could experience the largest thermal expansion.

In good design practice, in order to reduce the size of the expansion tank, it is preferred to install the tank before the system pump.

The size of the tank can also be reduced when the tank is installed at the highest point of the piping system where the pressure is

the lowest.

As an example, the lower temp. for a heating system is usually normal ambient temp. at fill conditions (e.g., 50°F) & the higher

temp. is the operating supply water temp. for the system. For a chilled water system, the lower temp. is the design chilled water

supply temp., & the higher temp. is ambient temp. (e.g., 95°F or 115oF for KSA hot areas). For a dual-temp. hot/chilled system,

the lower temp. is the chilled water design supply temp., & the higher temp. is the heating water design supply temperature. Pressures at the expansion tank are generally set by the following parameters: 1) The lower pressure is usually selected to hold a positive pressure at the highest point in the system (usually about 10 psig

or 24.696 psia).

2) The higher pres. is normally set by the max. pres. allowable at the location of the safety relief valve(s) without opening them.

Other considerations are to ensure that (1) the pres. at no point in the system will ever drop below the saturation pres. at the

aTable 2 Steel Pipe Data (excerpts) (c) 2000 ASHRAE Hndbk, Chap.40 HVAC Sys.& Equipment

Flow Area.a

mm2

C68
Edgar I. Lim: Data taken from Marks Handbook. This pipe size is not available in Table 2 of ASHRAE.

Expansion Tank EasyCalc

eil software 2008 3 Expansion Tank EasyCalc

operating system temp. and (2) all pumps have sufficient net positive suction head (NPSH) available to prevent cavitations.

Enable/Disable notes on page 2 above yesExample Calculation of Expansion Tanks From 2000 ASHRAE Handbook, HVAC Systems & Equipment, Chap. 12

The minimum pressure at the tank is 10 psig (24.7 psia) & the maximum pressure is 25 psig (39.7 psia). (Atmospheric pressure

is 14.7 psia.) The volume of water is 3000 gal. The piping is steel.

1. Calculate the required size for a closed tank (plain steel tank) with an air/water interface.

From Table 3 in Chap. 6 of the ASHRAE Handbook—Fundamentals,

Given Data:ASHRAE Data Users Entry

Example 2 Data Page1

= 3000 3000

= 40 40

= 220 220 ASHRAE Data in Formula as per Example no.1)

= 14.7 14.696

= 24.7 4.0

= 39.7 39.7

= 0.01602 0.01602

= 0.01677 0.01677

Δt = 180 180 Answers: Volume of Diaphragm Expansion Tank

α = 6.50E-06 6.50E-06 578 Gallons (ASHRAE Data as per Example no.1)

= 578 39 39 Gallons ( User's Entries calculation at page 1)

Given Data: ASHRAE Data Users EntryExample 2 Data Page1

= 3000 3000

= 40 40 ASHRAE Data in Formula as per Example no.2)

= 220 220

= 24.7 4.000

= 39.7 39.7

= 0.01602 0.01602

= 0.01677 0.01677

Δt = 180 180 Answers: Volume of Diaphragm Expansion Tank

α = 6.50E-06 6.50E-06 344 Gallons (ASHRAE Data as per Example no.2)

= 344 144 144 Gallons ( User's Entries calculation at page 1)

EXPANSION TANK MINIMUM PRESSURE

The expansion tank must be pressurized to provide at least 4 psi (28 kPa) of positive pressure at the highest point in the

hydronic piping system. This will also ensure no air is drawn into the piping. The amount of charge pressure in pounds per

square inch (psi) that is required in the expansion tank is equal to 4 psi (28 kPa) plus the height (in feet) from the chiller

to the highest point in the hydronic system divided by 2.31.

of 100 feet. The total pressure required in the expansion tank is:

Example 1. Size an expansion tank for a heating water system that will be operated at a design temperature range of 180 to 220°F.

Solution: For lower temperature t1 , use 40°F

v1 at 40°F = 0.01602 ft3/lb v2 at 220°F = 0.01677 ft3/lb

Vs Solution: Using Equation (12), t1

t2

Pa

P1

P2

v1

v2

Vt=

Vt Vt=

Example 2. If a diaphragm tank were to be used in lieu of the plain steel tank, what tank size would be required?

Solution: Using Equation (14),Vs

t1

t2

P1

P2

v1

v2

Vt=

Vt Vt=

Example: The expansion tank elev. is 10 feet. The hydronic system is piped to an air handler on the roof with an elevation

E113
Edgar I. Lim: To hide notes on page 2 for report purposes, select "no" in the dropdown list. Otherwise select "yes" to enable the notes.

Expansion Tank EasyCalc

eil software 2008 4 Expansion Tank EasyCalc

4 psi + (100 ft – 10 ft)/2.31 = 42.96 psi

Thus an expansion tank with a pre-charged pres. at 40 psi from factory will require an additional 3 psi pressure.

Boiler System Types:

1. Low Temperature Heating Water Systems: Add 14.696 to get absolute pressure at sea level.

a. 250°F. &Less.

b. 160 psig maximum. 1. 15 Psig 6. 200 Psig

2. Medium Temperature Heating Water Systems: 2. 30 Psig 7. 250 Psig

a. 251–350°F. 3. 60 Psig 8. 300 Psig

b. 160 psig maximum. 4. 125 Psig 9. 350 Psig

3. High Temperature Heating Water Systems: 5. 150 Psig

a. 351–450°F.

b. 300 psig maximum.

EXPANSION TANKS COMMERCIAL LISTED SIZES (ARMSTRONG)

EXPANSION TANKS LISTED COMMERCIAL SIZES

Diaphragm Tank Bladder Tank Configuration Closed Tank

liters gallons liters gallons liters gallons

29.5 7.8 200.6 53 56.8 15.0

41.3 10.9 302.8 80 90.8 24.0

82.1 21.7 401.3 106 113.6 30.0

127.2 33.6 499.7 132 151.4 40.0

168.1 44.4 598.1 158 227.1 60.0

210.8 55.7 798.7 211 302.8 80.0

257.4 68.0 999.3 264 378.5 100.0

291.5 77.0 1200.0 317 454.2 120.0

340.7 90.0 1400.6 370 511.0 135.0

416.4 110.0 1597.4 422 662.4 175.0

499.7 132.0 1998.7 528 832.8 220.0

601.9 159.0 2498.4 660 908.5 240.0

798.7 211.0 2998.0 792 1154.6 305.0

3997.4 1056 1116.7 295.0

1514.2 400.0

1911.6 505.0

1987.3 525.0

A. Class I Boilers. ASME Boiler &Pressure Vessel Code, Section I:

1. Steam Boilers, Greater than 15 Psig

2. Hot Water Boilers:

a. Greater than 160 Psig

b. Greater than 250°F.

B. Class IV Boilers. ASME Boiler &Pressure Vessel Code, Section IV:

1. Steam Boilers, 15 psig &less

2. Hot Water Boilers:

a. 160 psi &less

Common Boiler Design Pressures ( psig.)

A174
Edgar I. Lim: Manufacturers of Expansion Tanks: Bell and Gossett; Taco; Amtrol; Woods
A175
Edgar I. Lim: ASME Pre-charged Diaphragm Expansion Tank, stamped 125 PSI working pressure. Tank supplied with a heavy-duty butyl diaphragm. Tank shall provided with a NPT system connection. An air charging valve connection (standard tire valve) is also provided to facilitate adjusting pre-charge pressure, to meet the actual system conditions. Consult factory for 175, 200 and 250 psi applications.
E175
Edgar I. Lim: ASME Pre-charged Bladder Expansion Tank, stamped 125 PSI working pressure. Tank shall be supplied with a ring base, lifting rings, and a NPT system connection. An air charging valve connection (standard tire valve) shall be also provided, to facilitate adjusting pre-charge pressure to meet the actual system conditions. Consult factory for 175, 200 and 250 psi applications.

Expansion Tank EasyCalc

eil software 2008 5 Expansion Tank EasyCalc

b. 250°F. &less

Hot Water Boilers Steam Boilers ChillersA. Boiler Types: A. Boiler Types: A. Chiller Types:

1. Fire Tube Boilers: 1. Fire Tube Boilers: 1. Centrifugal:

a. 15–800 BHP. a. 15–800 BHP. a. 200 Tons &Larger.

b. 500–26,780 MBH. b. 518–27,600 Lb./Hr. b. 0.55–0.85 KW/Ton.

c. 30–300 psig. c. 15–300 psig. c. 4.14–6.39 COP.

2. Water Tube Boilers: 2. Water Tube Boilers: d. Turndown Ratio, 100% to 10%.

a. 350–2,400 BHP. a. 350–2,400 BHP. 2. Reciprocating:

b. 13,000–82,800 MBH. b. 12,075–82,800 Lb./Hr. a. 200 Tons &Smaller.

c. 30–525 psig. c. 15–525 psig. b. 0.90–1.30 KW/Ton.

3. Flexible Water Tube Boilers: 3. Flexible Water Tube Boilers: c. 2.70–3.90 COP.

a. 30–250 BHP. a. 30–250 BHP. d. Turndown Ratio, Staged or Stepped

b. 1,000–8,370 MBH. b. 10,000–82,000 Lb./Hr. based on nos of cyl.& unloadingcontrol.

c. 0–150 psig. c. 15–525 psig. 3. Rotary Screw:

4. Cast Iron Boilers: 4. Cast Iron Boilers: a. 50–1100 Tons.

a. 10–400 BHP. a. 10–400 BHP. b. 1.00–1.50 KW/Ton.

b. 345–13,800 MBH. b. 1,035–8,625 Lb./Hr. c. 2.34–3.50 COP.

c. 0–40 psig. c. 0–150 psig. d. Turndown Ratio, 100% to 25%.

5. Modular Boilers: 5. Electric Boilers: 4. Absorption (Steam or Hot Water):

a. 4–115 BHP. a. 15–5,000 KW. a. 100 Tons &Larger.

b. 136–4,000 MBH. b. 51–17,065 MBH. b. 18,750 Btuh/Ton; 0.64 COP 1-Stage.

c. 0–150 psig. c. 0–300 psig. c. 12,250 Btuh/Ton; 0.98 COP 2-Stage.

6. Electric Boilers: d. Turndown Ratio, 100% to 10%.

a. 15–5,000 KW. 5. Absorption (Gas or Oil):

b. 51–17,065 MBH. a. 100 Tons & Larger.

c. 0–300 psig. b. 11,720 Btuh/Ton; 1.02 COP Gas.

c. 12,440 Btuh/Ton; 0.96 COP Oil.

d. Turndown Ratio, 100% to 10%.

Low Temperature Heating Water Systems: Chilled Water Systems:

1. Leaving Water Temperature (LWT): 180–200°F. 1. Leaving Water Temperature (LWT): 40–48°F.

2. ΔT Range 20–40°F. (60°F.Maximum)

3. Low Temperature Water 250°F. & less; 160 psig maximum 2. ΔT Range 10–20°F.

Medium &High Temperature Heating Water Systems: Low Temperature Chilled Water Systems

1. Leaving Water Temperature (LWT): 350–450°F. (Glycol or Ice Water Systems)

2. ΔT Range 20–100°F. 1. Leaving Water Temperature (LWT): 20–40°F.

3. Medium Temperature Water 251–350°F.; 160 psig maximum (0°F. minimum)

4. High Temperature Water 351–450°F.; 300 psig maximum 2. ΔT Range 20–40°F.

Dual Temperature Water System Types: Condenser Water Systems:

1. Leaving Cooling Water Temperature 40–48°F. 1. Entering Water Temperature (EWT): 85°F.

2. Cooling ΔT Range 10–20°F. 2. ΔT Range 10–20°F.

Expansion Tank EasyCalc

eil software 2008 6 Expansion Tank EasyCalc

3. Leaving Heating Water Temperature: 180–200°F. 3. Normal ΔT 10°F.

4. Heating ΔT Range 20–40°F. Water Source Heat Pump Loop

1. Range: 60–90°F.

2. ΔT Range 10–15°F.

AC Condensate Flow:

1. Range: 0.02–0.08 GPM/Ton 5. AHU (50% Outdoor Air): 0.065 GPM/1,000 CFM

2. Average: 0.04 GPM/Ton 6. AHU (25% Outdoor Air): 0.048 GPM/1,000 CFM

3. Unitary Packaged AC Equipment: 0.006 GPM/To 7. AHU (15% Outdoor Air): 0.041 GPM/1,000 CFM

4. AHU (100% outside Air): 0.100 GPM/1,000 CFM 8. AHU (0% Outdoor Air): 0.030 GPM/1,000 CFM

AC Condensate Pipe Sizing

1. Minimum Pipe Sizes are given in the following table.

AC Tons of Refrigeration 0-20 21-40 41-60 61-100 101-250 251 &Larger

Minimum Drain size (inch) 1" 1-1/4" 1-1/2" 2" 3" 4"

Expansion Tanks &Air Separators

A. Minimum (Fill) Pressure:

1. Height of System + (5 to 10 psi)

or 5–10 psi, whichever is greater.

B. Maximum (System) Pressure:

1. 150 Lb. Systems: 45–125 psi

2. 250 Lb. Systems: 125–225 psi

C. System Volume Estimate:

1. 12 Gal./Ton

2. 35 Gal./BHP

The sizing of low-temperature hot water pipes is usually based on a pressure drop of 1 to 3 ft per 100 ft of pipe length. For a small

low-temp. hot water heating system, an open-type expansion tank is often used. An open expansion tank has the disadvantage of

allowing air to enter the system via absorption in the water. A diaphragm tank is often used for a large system. On-line circulating

pumps with low head are often used.

Table 1 Standard Atmospheric Data Atmospheric Data Calculation

for Altitudes to 10 000 m For Different Altitudes

Altitude, Pressure, Altitude, Pressure,

m kPa psia m kPa psia

−500 107.478 15.588 555 94.833 13.754

0 101.325 14.696

500 95.461 13.845

1 000 89.875 13.035

1 500 84.556 12.264

2 000 79.495 11.530

2 500 74.682 10.832

3 000 70.108 10.168

4 000 61.64 8.940

5 000 54.02 7.835

6 000 47.181 6.843

Expansion Tank EasyCalc

eil software 2008 7 Expansion Tank EasyCalc

7 000 41.061 5.955

8 000 35.6 5.163

9 000 30.742 4.459

10 000 26.436 3.834

(c) 2005 ASHRAE Handbook, Fundamentals, Chapter 6

Expansion Tank EasyCalc

eil software 2008 8 Expansion Tank EasyCalc

Expansion Tank EasyCalc

eil software 2008 9 Expansion Tank EasyCalc

Expansion Tank EasyCalc

eil software 2008 10 Expansion Tank EasyCalc

Example Calculation of Expansion Tanks From 2000 ASHRAE Handbook, HVAC Systems & Equipment, Chap. 12

The expansion tank must be pressurized to provide at least 4 psi (28 kPa) of positive pressure at the highest point in the

hydronic piping system. This will also ensure no air is drawn into the piping. The amount of charge pressure in pounds per

The expansion tank elev. is 10 feet. The hydronic system is piped to an air handler on the roof with an elevation

Expansion Tank EasyCalc

eil software 2008 11 Expansion Tank EasyCalc

Thus an expansion tank with a pre-charged pres. at 40 psi from factory will require an additional 3 psi pressure.

Expansion Tank EasyCalc

eil software 2008 12 Expansion Tank EasyCalc

based on nos of cyl.& unloadingcontrol.

b. 18,750 Btuh/Ton; 0.64 COP 1-Stage.

1. Leaving Water Temperature (LWT): 40–48°F.

1. Leaving Water Temperature (LWT): 20–40°F.

Expansion Tank EasyCalc

eil software 2008 13 Expansion Tank EasyCalc

Expansion Tank EasyCalc

eil software 2008 14 Expansion Tank EasyCalc

ASHRAE FundamentalsTable 3 Thermodynamic Properties of Water at Saturation

Temp., Specific Vol. Temp., Specific Vol. Temp., Specific Vol. Temp., Specific Vol. Temp., Specific Vol.

°F °F °F °F °F

32 0.01747 60 0.01604 88 0.01609 116 0.01619 144 0.01631

33 0.01602 61 0.01604 89 0.0161 117 0.01619 145 0.01632

34 0.01602 62 0.01604 90 0.0161 118 0.0162 146 0.01632

35 0.01602 63 0.01604 91 0.0161 119 0.0162 147 0.01633

36 0.01602 64 0.01604 92 0.01611 120 0.0162 148 0.01633

37 0.01602 65 0.01604 93 0.01611 121 0.01621 149 0.01634

38 0.01602 66 0.01604 94 0.01611 122 0.01621 150 0.01634

39 0.01602 67 0.01605 95 0.01612 123 0.01622 151 0.01635

40 0.01602 68 0.01605 96 0.01612 124 0.01622 152 0.01635

41 0.01602 69 0.01605 97 0.01612 125 0.01623 153 0.01636

42 0.01602 70 0.01605 98 0.01612 126 0.01623 154 0.01636

43 0.01602 71 0.01605 99 0.01613 127 0.01623 155 0.01637

44 0.01602 72 0.01606 100 0.01613 128 0.01624 156 0.01637

45 0.01602 73 0.01606 101 0.01613 129 0.01624 157 0.01638

46 0.01602 74 0.01606 102 0.01614 130 0.01625 158 0.01638

47 0.01602 75 0.01606 103 0.01614 131 0.01625 159 0.01639

48 0.01602 76 0.01606 104 0.01614 132 0.01626 160 0.01639

49 0.01602 77 0.01607 105 0.01615 133 0.01626 161 0.0164

50 0.01602 78 0.01607 106 0.01615 134 0.01627 162 0.0164

51 0.01602 79 0.01607 107 0.01616 135 0.01627 163 0.01641

52 0.01603 80 0.01607 108 0.01616 136 0.01627 164 0.01642

53 0.01603 81 0.01608 109 0.01616 137 0.01628 165 0.01642

54 0.01603 82 0.01608 110 0.01617 138 0.01628 166 0.01643

55 0.01603 83 0.01608 111 0.01617 139 0.01629 167 0.01643

56 0.01603 84 0.01608 112 0.01617 140 0.01629 168 0.01644

57 0.01603 85 0.01609 113 0.01618 141 0.0163 169 0.01644

58 0.01603 86 0.01609 114 0.01618 142 0.0163 170 0.01645

ft3/lbw ft3/lbw ft3/lbw ft3/lbw ft3/lbw

59 0.01603 87 0.01609 115 0.01619 143 0.01631 171 0.01646

172 0.01646 206 0.01667 270 0.01717 338 0.01785 415 0.01886

173 0.01647 207 0.01668 272 0.01719 340 0.01787 420 0.01894

174 0.01647 208 0.01669 274 0.01721 342 0.01789 425 0.01901

175 0.01648 209 0.01669 276 0.01722 344 0.01792 430 0.01909

176 0.01648 210 0.0167 278 0.01724 346 0.01794 435 0.01918

177 0.01649 212 0.01671 280 0.01726 348 0.01796 440 0.01926

178 0.0165 214 0.01673 282 0.01728 350 0.01799 445 0.01935

179 0.0165 216 0.01674 284 0.01730 352 0.01801 450 0.01943

180 0.01651 218 0.01676 286 0.01731 354 0.01804 455 0.01952

181 0.01651 220 0.01677 288 0.01733 356 0.01806 460 0.01961

182 0.01652 222 0.01679 290 0.01735 358 0.01808 465 0.01971

183 0.01653 224 0.0168 292 0.01737 360 0.01811 470 0.01980

184 0.01653 226 0.01682 294 0.01739 362 0.01813

185 0.01654 228 0.01683 296 0.01741 364 0.01816

186 0.01654 230 0.01684 298 0.01743 366 0.01818

187 0.01655 232 0.01686 300 0.01745 368 0.01821

188 0.01656 234 0.01688 302 0.01747 370 0.01823

189 0.01656 236 0.01689 304 0.01749 372 0.01826

190 0.01657 238 0.01691 306 0.01751 374 0.01828

191 0.01658 240 0.01692 308 0.01753 376 0.01831

192 0.01658 242 0.01694 310 0.01755 378 0.01834

193 0.01659 244 0.01695 312 0.01757 380 0.01836

194 0.01659 246 0.01697 314 0.01759 382 0.01839

195 0.0166 248 0.01698 316 0.01761 384 0.01842

196 0.01661 250 0.01700 318 0.01763 386 0.01844

197 0.01661 252 0.01702 320 0.01765 388 0.01847

198 0.01662 254 0.01703 322 0.01767 390 0.01850

199 0.01663 256 0.01705 324 0.01770 392 0.01853

200 0.01663 258 0.01707 326 0.01772 394 0.01855

201 0.01664 260 0.01708 328 0.01774 396 0.01858

202 0.01665 262 0.01710 330 0.01776 398 0.01861

203 0.01665 264 0.01712 332 0.01778 400 0.01864

204 0.01666 266 0.01714 334 0.01780 405 0.01871

205 0.01667 268 0.01715 336 0.01783 410 0.01878