Pressure Relief Valve Leak

[Jeff Pogwizd]

I had a leak from the pressure relief valve on my gas hot water heater. I did some research and ended up replacing this valve with a new one with the same specs. That said, I still have a leak. What should my next steps be?

 

[FullySprinklered]

After all is said and done, you most likely will be replacing the expansion tank and pressure regulating valve.

 

[Sponsor]

 

[Terry]

After all is said and done, you most likely will be replacing the expansion tank and pressure regulating valve.

The garden department of a hardware store should carry pressure gauges that will fit a hosebib. Check your house pressure. It should be 80 PSI or less. If more you may need to install or replace a PRV. Pressure Reducing Valve.

 

[Jadnashua]

That valve will open with one of two situations assuming it is working properly:
- the pressure exceeds 150psi
- the temperature excedes 210F

YOu'd probably know if the water was near boiling. You may not notice that the pressure is high. If you have a closed system, if you don't have a functioning expansion tank, the pressure WILL get high enough to open the T&P valve.

 

[Alucard]

I have this same issue and it started when I determined our water pressure was 80 PSI or slightly higher so I put a reducing valve on so our system became a close system. After months or even a year or more of dripping, I took a pressure reading and determined our water pressure, after valve, is at 40 PSI-I screwed a gauge onto our laundry tub faucet. I then installed an expansion tank on the cold water side close to water heater, with a bladder and added air to the tank so it would be 40 PSI, same as house pressure. After a couple of days I'm still getting drips and the expansion tanks seems like it's empty. I took another air pressure reading on the expansion tank and it appeard to be about 35 PSI, probably from checking it so often. Nevertheless, it's still empty. It's probably unlikely but could the pressure relif valve on water heater be bad and therefore, releasing before the expansion tank has a chance to take on water? I did notice the relief valve on the water heater has alot of corrosion and deposits, probably from dripping so much. I opened it all the way hoping that perhaps there was sediment not allowing it to close fully but to no avail, still drips. I'm going to replace it anyway and see what happens as I'm not sure what else I can do. I don't think the water temperature goes over 210 or I would probably be able to tell and I have it set on a lower setting. The water dripping is hot but don;t think it's anywhere near boiling.

 

[Jadnashua]

The T&P valve is designed as a safety device and isn't really configured to operate reliably when opened numerous times a day as you use hot water and the expansion causes it to open. Worst case, it lodges shut and won't operate, allowing pressure to rise and things can literally explode if there's a fault. What you are seeing with it not resealing after long operation and mineral deposits is typical. A new one should permanently solve the problem. If there are deposits on the seal, sometimes opening it up fully will flush them out.

If the pressure tank's pressure dropped (you can't check it with water pressure on the other side - you have to shut the water off and relieve water pressure first), it could slightly change with temperature, but 5# is a lot. Get yourself a better cap for the air valve and make sure it is tight. If you didn't put the cap on, install it. The Schrader valve works much better with the cap on to help seal things.

 

[Alucard]

I replaced the safety valve and that was indeed the problem. No more dripping. I suppose it opening and closing so often is what did it in. I think the same things is happening with the safety valve on my boiler for house heating.