I installed a brand new water heater about 4 months ago, noticed that that relief valve was dripping like crazy. Checked the expansion tank and it was filled with water. I replaced it with a brand new expansion tank only a few months old. It was properly installed, got an accurate reading for water pressure from the city, set the air in the tank to a few pounds under that according to instructions.
Problem was fixed, the relief valve stopped dripping altogether for at least a month. This recently started back up however and right in the middle of a home inspection no less (I am currently selling the home). The home inspector included in his report that I have a faulty safety relief valve on my water heater and it needs to be replaced. The buyers in turn demanded that I replace the safety relief valve despite the fact that I am not even sure if that is the problem.
I even explained to the home inspector and buyers when they were there that the water heater and expansion tank are brand new. In your opinion is this a problem with the relief valve or the expansion tank or both? Is it normal to buy a new water heater with a faulty relief valve? Is it normal for a brand new expansion tank to already be taking on water?
I last measured this a few months ago, after opening faucet and releasing pressure from the water heater I got 30 psi. The water heater temperature is between HOT and A, but the knob goes all the way up to C. I filled up my NEW expansion tank to 28 psi and the dripping stopped completely for over a month. My father in law seems to think that calcium can buildup around the relief valve and cause this dripping I am seeing and that it is more likely to be a problem with the relief valve than the brand new tank.