Expansion Tank

[fayazdin1]

Dear Members,
My question is why do we need expansion tank on chilled water system? Here is the situation ……….
Ambient temperature = 40 deg. C

Chilled water temperature = 5 deg. C
Chiller Tons: 100

Thermal expansion of water is 0.00214 1/ deg. C = 0.0043 gallons per 25 deg. C
System volume = 1200 gallon

Most probably, chiller will start when outside temperature is 25 deg. C, that gives us 25 deg. C delta T. Total system water volume expansion would be 1200-gallons X 0.0043 = 5.16 gallons
This is a very small expansion compared with the size of the system. Elbows, fittings and expansion joints can handle this expansion.
Do we really need an expansion tank?

Sincerely,
Fayaz Din

 

[willard3]

In short, yes, you need an expansion tank.

 

[Drazen]

yes, you really need it because water is incompressible fluid and even few drops will make a difference, and without expansion tank your system can have uncontrolled surges, and you can even damage either circulation pumps or other equipment.

in best case your safety valve will frequently leak and you would need to add make-up water permanently.

 

[DrRTU]

Yes and run the numbers.

http://www.amtrol.com/support/extrol_com_sizing.html

 

[tcihvacff1]

Expansion tank has to be use to avoid VOLUMETRIC EXPANSION of water, which may lead to leakages at weak points or bursting of pipe in worst conditions in a closed loop chilled water system...

 

[fayazdin1]

Thank you all