I'm finishing the basement and along with that project, I finally got around to changing out the WH which I've had "issues" with over the years. The old one was junk from day 90 and now about at the end of it's 9 year warranty anyway. So instead of repairing it, I put in a new one, relocated it and added a second WH in series while I was at it for some needed extra HW capacity.
The new heaters were plumbed for H2O and functional, I was going to pipe the T&P valves the next day. Turned out to be a good thing I had to wait on that piping because I discovered the T&P's were "relieving" (via the 2-3 gallons in my basement floor the next AM). Had I only installed one heater, I'd have thought it was leaking, but as both drain pans on both new heaters were full, I knew I had a simultaneous discharge on both T&P valves (first of 2 new WH's is electric and not wired yet). So, I figured I had to have something up with pressure. A $10 Watts guage confirmed it, I found my PRV must be bad as the static pressure in the house was 120-130, peaking to 150+ . Thus the T&P relief. (City water is at ~120-130)
My expectation is that this has been going on for possibly years and I didn't know becasue the T&P was plumbed to a drain, and I would have never known if was relieving regularly. This might explain a not to distant failure of some poly lines in the old fridge (now replaced) and a subsequent poly line failure on the dishwasher, too
A little quick research, and I found I was missing the integral component - the expansion tank. While I did the repair and new WH install myself, the original design and install including the PRV was done by a "pro". So I don't get credit for the original miss on the no-expansion tank.
Of course I have replaced the PRV. Mine is a Watts with unions on both ends so the $35 at Home Depot for a new one and 10 minutes to change was better for me that to try to see what was wrong with the old one. Biggest problem I have right now is the wife is ill with the 50psi shower, she has become accustomed to the pressure washer we/she had last week .
Now to the expansion tank. I have a variety of places I can locate it, none are good. I've looked at every brand out there I think. I can only find one that comes with any warranty. It was a hair more expensive, mostly due to the special order, so for peace of mind, I have it on the way (State/AO Smith). They are probably all made at the same plant in China, but at least State was banking on it not failing for 5 years.
My question to you experienced guys is this; when these little expansion tanks fail, where do they fail? When I say fail, I don't mean internally with a bladder leak, I mean externally or anyplace that would cause a water leak. All my install locations are bad for leaks and I don't have any practical way (place) to put a drain pan under the thing. I envision (have nightmares about) a split expansion tank seam with water spewing out the side (picture - old submarine war movie). Do they fail like that, or just start to seep and drip?
For any that you have seen leak, where and how do they leak? How reliable are they (leak wise)?
And, for my wife's sake, I figured I'd turn the PRV "up" to maybe 75 psi (and charge the expansion tank appropriately). Any problems with that plan?