Another Leaking T&R Valve

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Another Leaking T&R Valve

Postby rymillsy » Wed Apr 19, 2017 7:38 am

Hey guys, I've been scouring the internet, consulting a couple contractor buddies and the guys at my local Ace Hardware and I'm pretty much out of ideas. I've tried searching the forums here to get an answer but couldn't really find any new info. Here's a description of my problem with my 40 gal, gas WH.
- noticed T&R valve leaking a few months ago and hadn't ever dealt with that so watched Shannon's vid on swapping one out. Grabbed a new one and installed it without any issues.
- new valve was a longer shank than the original but the sensor was the same length so figured I was ok. Valve worked fine for about a week then starting dribbling/leaking again...but more than the first one (mind you, it only leaks when the burner kicks thermal expansion?)
- turned the temp down one click below the "recommended" setting to see if maybe water was getting too hot, but also checked at full hot water in kitchen and bathroom sinks. Water was hot, but nowhere near 210 as I could hold my hand under it for 8-10 seconds before it got too uncomfortable+when I lowered the temp the valve still leaked when burner kicked on
- that lead me to think the pressure was too high, so threw a gauge onto the hose bib. PSI was constant at about 50 PSI. (there is no PRV or expansion tank on the system and never has been as it's never been needed for the 10 years I've lived in the house, which was built in the 70's)
- After consulting some smarter guys than myself at Ace, they said it was because I installed a long shank T&R valve, so I got a new shorter one (again, same length sensor rod) and installed without any issues
- Refilled tank, turned gas back on and a few minutes after burner kicked on the T&R valve started dribbling again, so went back through the whole process again of turning down temp & checking PSI. Same results again
- last night, I opened hot water on kitchen faucet to full, drained about 10 gal of water from the tank then kept faucet on while refilling and opened T&R valve a few times to make sure all air was out of lines and everything pressurized correctly...she still leaks from the same valve again and it's enough to be a significant problem for the home inspection I'll be having soon (did I mention I'm selling the house? :) )

At this point, I'm thinking my only option is to throw an expansion tank onto the system but I have never had/needed one before and if the PSI coming in from city is significantly lower than pressure pushing back from WH then why the sudden change of my open system no longer pushing excess pressure back into city main? Is an expansion tank going to make the difference in this case or should I be looking at something else? THANKS!

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Re: Another Leaking T&R Valve

Postby Shannon » Wed Apr 19, 2017 8:25 am

Connect your pressure tester and then run the hot water until the water heater cuts in. Close the hot water tap and note the pressure on the gauge. Watch to see if the pressure creeps up on the gauge as the water heater heats the water. My guess is that you have a back check valve and as the heater heats the water the extra pressure has no where to go. Why this just became a problem? I do not know? I think an expansion tank will be your fix in this case.
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Posts: 2
Joined: Wed Apr 19, 2017 7:14 am
Location: Columbus, OH

Re: Another Leaking T&R Valve

Postby rymillsy » Wed Apr 19, 2017 9:39 am

Will do give that a shot. Thanks Shannon!

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Re: Another Leaking T&R Valve

Postby Mastercarpentry » Thu Apr 20, 2017 3:43 am

A friend had a leaky T&P on a ten-year old house and replaced it. A month later it was leaking again, so he put another new one on. Two months later same thing. In the interim he also had a toilet fill valve refuse to shut of so he replaced that. Finally he checked the incoming pressure from the meter- it was 160 PSI- yikes! Turns out the city had tied in a different main supply nearby, raising the pressure in the whole neighborhood and now other folks were having problems. None of those houses had pressure regulators as it wasn't required when they were built, but other nearby houses did so they didn't experience any problems.

So check your water pressure at the WH tank and at your regulator if you've got one. And I'd recommend adding a regulator if you don't have one just to protect yourself from whatever may happen with the mains.


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