Originally Posted By: dnewby This post was automatically imported from our archived forum.
Hello to all. I am a new member. I have seen this expansion tank before on a water heater and do not know what its function is. Is it suppose to be on the cold water side? Thanks.
Originally Posted By: dhadler This post was automatically imported from our archived forum.
I would think it should be on the hot water side? Wouldn’t it still work to control water hammer as well as do it’s real function? Kill two birds with one stone.
Just asking 
-- Darrell Hadler
Five Star Home Inspections
Medicine Hat, Alberta CANADA
Originally Posted By: rmoore This post was automatically imported from our archived forum.
Donna,
It?s more properly referred to as a thermal expansion tank. On a closed supply system, such as occurs when you have a backflow preventer (check valve) or pressure regulator at the supply entrance, the heated water tries to expand and has no where to go. So?instead it increases pressure. Depending on initial pressure, and the amount of heat added, this can often lead to pressures over 150, which will cause the TPR valve to leak or possibly damage the plumbing.
The flexible bladder in the TX-tank allows this thermal expansion somewhere to go with only a small increase in pressure. If the system is ?open? to the main supply, then probably not needed (may be ?required?), but they do also help with water hammer and some install them just for that.
Usually installed on the cold water side, although I can?t think of a reason they wouldn?t work on the hot side other than the rubber bladder may deteriorate faster.
-- Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com