1. 1 Expansion Tanks

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3. 3 Expansion Tanks WHY USE THEM TYPES LOCATION SIZING

4. 4 Expansion Tanks WHY USE THEM?

5. 5 Air Charge System Fluid Low Temperature ConditionHigh Temperature Condition System Effect of Temperature Change Water is incompressible It expands when heated If the volume of the system cannot change, pressure will increase

6. 6 Standard Compression Tank Diaphragm Tank Bladder Tank Types of Tanks

7. 7 Expansion Tank Types Compression Tank Water Gas System Bladder Water Gas System Diaphragm Tank Bladder Tank (Larger Systems) Charging Connection Charging Connection Diaphragm Water

8. 8 Standard Compression Tank System Connection

9. 9 Standard Tank Fitting Purpose: Separates air bubbles from the system liquid at the boiler. Prevents free air from spreading into the system. Still found in older, larger volume boilers. Air Water

10. 10 Boiler P NOTE: No auto air vents! Or, valved off if used

11. 11 Diaphragm Tank System Connection Air Charge What happens if air charge is lost?

12. 12 System Connection Air Charge Replaceable bladder Bladder Tank

13. 13 Effect of the “net expansion” Absorbs the net thermal expansion, V 1 – V 2, keeps the system within the “allowable pressure rise” band. Cold Warming Design Temperature P1V1P1V1 P2V2P2V2

14. 14 Compression or Diaphragm Tanks? Compression Water and air in contact May be larger, heavier Require tank fittings Rarely require repair Low initial cost Difficult initial set up Seismic Considerations Diaphragm/Bladder Impermeable barrier Probably smaller Require vents and thermal loop Repair difficult or impossible Higher initial cost

15. 15 Location: At the POINT OF NO PRESSURE CHANGE

16. 16 Closed Loop System

17. 17 Closed Loop System

18. 18 Closed Loop System 12 PSI Point of no pressure change

19. 19 Closed Loop System 12 PSI Point of no pressure change Pump 14 PSID

20. 20 Closed Loop System 12 PSI Point of no pressure change Pump decreases pressure here to -2 PSI 14 PSID across system

21. 21 Closed Loop System 12 PSI Point of no pressure change Pump increases pressure here to 26 PSI Pump 14 PSID

22. 22 Closed Loop System 12 PSI Point of no pressure change Pump 14 PSID 5 PSI 19 PSI

23. 23 Closed Loop System 12 PSI Air Charge 12 PSI

24. 24 Bladder Tank Rolairtrol Air Separator Cold Water Supply Reducing Valve From System Blowdown To Pump Suction By-Pass with Globe Valve System Components High Capacity Air Vent

25. 25 Expansion Tanks Tank System Drain

26. 26 Expansion Tank Sizing Required Data: –Total System Water Content (Volume) –Average Design Water Temperature –Minimum Fill Pressure –Maximum Operating Pressure (usually 10% below relief valve )

27. 27 Expansion Tank Sizing Example #1: 1200 Gallon System 12 PSI Fill 180 F Temperature 75 PSI Relief Valve 5 Gallons in Boiler

28. 28 Expansion Tank Sizing Example #1: Required Data: –Total System Water Content (Volume) 1205 Gallons –Average Design Water Temperature 50 o F heated to 180 o F –Minimum Fill Pressure 12 PSI Fill –Maximum Operating Pressure (usually 10% below relief valve ) 65 PSI

29. 29 Expansion Tank Sizing Calculation Volume x (Net Water Expansion Factor) = Gallons Expanded Gallons Expanded / (Acceptance Factor) = Total Gallons Gallons Expanded = Acceptance Volume Total Gallons = Total Tank Volume

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32. 32 Calculation 1205 X 0.02757= 33.22 gals expanded 33.22 gals expanded / 0.665 = 49.95 gals Expansion Tank Sizing 50F heated to 180 F 12psi fill and 65psi maximum operating pressure

33. 33 Expansion Tank Sizing Calculation 1205 X.02757 = 33.22 Acceptance Volume 33.22 /.665 = 49.95 Total Tank Volume

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