Leaking Valve ... almost serious

[jebatty]

For no good reason, today I tested the pressure relief valve on my 1000 gal storage tank, and it worked ... too well. It wouldn't seal again, and I started to lose a good stream of water out of the relief line. Fortunately, I had installed plenty of isolation valves and I was able to quickly isolate the storage tank before losing too much water. The boiler system has been in operation since the winter of 2007-8. When I removed the defunct pressure valve, the seals inside were completely shot.

This could have been a much worse situation if the valve opened due to high pressure and then failed to seal again. I also have a pressure relief valve on the boiler itself, and this summer will be the time to test that valve. Maybe the lesson learned is to test the pressure relief valves periodically to make sure they function as intended.

A ride to the local hardware store, a new 30 psi relief valve, added some replacement water to the system, and all is back to normal again.

 

[velvetfoot]

Why the multiple prvs? Redundancy? Could've put both off a common pipe off the boiler, if that's the case. That's the heat generator, not the tank.

 

[maple1]

How did you test it?

 

[jebatty]

No good reason except for redundancy, actual reason more likely ignorance. No need for one on the LP tank, as it clearly can handle far more pressure than 30 psi. I can see a possible need for redundancy, though, and two on one pipe with isolation valves might be a good idea, or just one with an isolation valve and a spare on hand.

Tested by pulling the release lever on top of the valve. It should snap back and close, but when I pulled the lever, it also broke apart the seals inside the valve, thus causing the leak. Occasional testing seems to be a good idea.

 

[Bad LP]

Does the code not allow a valve in the same line as the PRV due to it inadvertently being closed?

Having a spare on the shelf sounds a lot more reasonable.

 

[velvetfoot]

You know, this reminds me of closing an isolation valve for an old toilet..you hope it actually works. Then again, that's not a safety hazard like the prv, unless you slip and fall on the water covered floor, hah. So, I guess it's good to test it once in a while, the moral of the story being not during heating season. Hopefully this thread doesn't cause copycat leakers while the heat is still on! Then again, it's unsafe to operate without a functioning prv, so maybe that'd be a good thing!

 

[peakbagger]

That's what homeowners insurance used to be for but most policies exclude basement flooding expect if you get a special rider.

Standard warning from most plumbers is never test a safety relief as they will generally leak. If you want to test it have a spare in hand or go with commercial valve. My old burnham wood boiler has two safeties, one was supposed to be set for 27 psi, the outlet is plumbed directly into the fire box so that if it pops it puts out the fire. The other one is 30 PSI piped to the floor. The 27 psi version leaks so I just replaced it with 30 PSI off the shelf version as getting a custom 27 psi valve is darn expensive.

 

[coaly]

Does the code not allow a valve in the same line as the PRV due to it inadvertently being closed?

Having a spare on the shelf sounds a lot more reasonable.

Correct, you can not be able to isolate a relief valve where one is required, as on the boiler. Since this one is not required, it could have a valve between tank and relief valve to allow replacement easily. If it is possible to plumb it away from the heat, this may extend life of components that degrade. Boilers and pressure tanks that are rarely shut down or depressurized have multiple relief valves on a rotating disc so they can be replaced on the plate and rotated into position.