Should I ad an expansion tank?

[tjbaudio]

With all of the other pluming I am doing right now it would be an easy time to add an expansion tank. The question is do I need one? Should I add one just because? I got a new water meter a few months ago and I have a 40 gallon gas HWH that is about 2 years old. The city is doing lots of work on the water plant and water lines in the streets. I could also add a permanent pressure gage. Any thoughts on this?

[Dunbar Plumbing]

Do you have a PRV on your incoming water line? If so, the tank is warranted.

[Gary Swart]

I just went through this, so maybe this will help. Get a pressure gauge and attach it to a hot water faucet. Watch what happens when the heater is in operation. My heat is gas, so it was quite simple to know when it began to heat. If yours is electric, run another hot water tap and drain the hot water down. If the pressure remains constant when the heater is operating, you don't need an expansion tank. If it rises, you do. Of course, it was already pointed out that if you have a PRV, you need the expansion tank because that creates a closed system. The new meter the water department put in may have a backflow prevention valve which also would cause a closed system. The pressure gauge will tell the tale very quickly.