T&P Valve Leaking After OWB Install

[Mister Twister]

Have any of you guys with OWB's had any problems with your Hot Water tank T&P leaking? First of all I am running my OWB at 180 deg. F. When I installed my sidearm heat exchanger the original T&P valve leaked after disturbing it. So I replaced it with a new one from the local hardware store for $8 and some change. That one is leaking real slowly also. I have a small bowl under the overflow or drain and it fills up slowly over a couple of days. Was I supposed to get a certain T&P valve or should I just try another one?

 

[projectsho89]

T & P valves are designed to relieve themselves (LOL) when the pressure hits 150 psi or the temperature of the water in the tank exceeds the design specification of the particular valve. 150F is a common value.

If you are NOT on a private well, pick up an in-expensive peak reading pressure gauges from one of the big box stores for under $10 and see which condition is probably causing it.

Steve

 

[ericjeeper]

Expansion tank

Install a hot water expansion tank somewhere in line. That should solve your problems..

 

[Labman]

Right. When you heat water in a tank, the excess has to go somewhere. If you have a backflow preventer or check valve in the system somewhere, now required for most public water systems, you need an expansion tank.

 

[projectsho89]

There's a reason I was trying to see if he was on a well or not....

 

[Mister Twister]

I have a hot water expansion tank intsalled already it is not being caused by pressure. I am going to just change the T&P Valve again this weekend it must be I got a bad one. The first one had a reason for failure it was old and when I cracked it it could not reseat.

Thanks,
Guys

I will let you know how it goes.......

 

[mini14]

have u checked to c if the expansion tank is filled with water, and if it is set to correct psi. 3 things cause tp to leak, bad tp valve, bad expansion tank, bad pressure reducing valve.

 

[cfabe]

How hot is the tank getting? Maybe the valve is too low of a temp and it's just doing it's job? If you've got a 150F TP Valve, and a 180F boiler heating it up, I could see it overheating the valve. Might have to go to a plumbing supply store and order a higher temp version.

 

[Mister Twister]

Pressure is correct on expansion tank and the T&P is 150 PSI and 210 Deg. F. I would notice 150 PSI at the faucet. It was reaching 100 PSI when I went to the public water system from a well a year ago that is why I put in the expansion tank. I will replace the T&P again this weekend and post the results.

Again thanks for the great feedback this site is great.

 

[Jkebxjunke]

100psi !!! dang... I would hate to be around that when a pipe or riser burst.... you might need a pressure reducing valve on the main line coming in the house... I think most residential pressures should be around 40-60psi?

 

[Mister Twister]

100psi !!! dang... I would hate to be around that when a pipe or riser burst.... you might need a pressure reducing valve on the main line coming in the house... I think most residential pressures should be around 40-60psi?

Yes it surprised me when I put a gauge in the line. I had always been on a well and when the hot water tank heated it must have pushed back towards the well. When I changed to the public water system there was a check valve in the meter pit out front of the house preventing back flow. It only occurred if I happened to not use water for a while and the hot water tank heated in that period. Since I put in the expansion tank it compensates for the condition like it is designed to do. It was a learning experience and I am luck nothing bursted. My old T&P did not leak through that so now you see my confusion.....

 

[Jkebxjunke]

Yes it surprised me when I put a gauge in the line. I had always been on a well and when the hot water tank heated it must have pushed back towards the well. When I changed to the public water system there was a check valve in the meter pit out front of the house preventing back flow. It only occurred if I happened to not use water for a while and the hot water tank heated in that period. Since I put in the expansion tank it compensates for the condition like it is designed to do. It was a learning experience and I am luck nothing bursted. My old T&P did not leak through that so now you see my confusion.....

it could be that it had enough 'crud' on it to sufficiently seal it... and it may have been made better

 

[Mister Twister]

Yes my thoughts exactly thats why I am going to try a different one this weekend.

 

[projectsho89]

Get a pressure regulator installed in there ASAP and install a new T & P valve. The excessive and continued high pressure will make a T & P valve fail quickly.

Verify the exp tank is not waterlogged (the small ones, 2 gallons or so, do not have a particularly long lifespan. Adjust the tank's pressure to match the new average line pressure and you'll find your situation will be resolved since it will then be a properly installed system.

Steve

 

[mtfallsmikey]

Also...remember that a T&P valve is like a circuit breaker...will fail to seal or hold after it has been tripped.

 

[ghitch75]

side arms are the most dangerous set up out there....should be a heat exchanger,pump,zone valve and aqua stat so you can set the temp to 120,130 ect...so you tank isn't sitting at 180....and when mixin' valves fail they fail to the hot not cold and little kids(and big kids) could loose fingers with 3 degree burns!!!

just my 2 cents

 

[Valkyrie Rider]

100psi !!! dang... I would hate to be around that when a pipe or riser burst.... you might need a pressure reducing valve on the main line coming in the house... I think most residential pressures should be around 40-60psi?

The plumbing code requires a pressure reducing valve if pressure is over 80psi. You aren't doing your plumbing fixtures any good with that much pressure!

 

[Jkebxjunke]

but although... it would sure make a good shower.... think of it with a massaging shower head...

 

[Mister Twister]

The plumbing code requires a pressure reducing valve if pressure is over 80psi. You aren't doing your plumbing fixtures any good with that much pressure!

My pressure was only that high when I switched to the public water system a year ago or what ever it was. I had to put an expansion tank in to rectify the problem. The pressure increased due to thermal expansion when it sat for a while and the hotwater tank came on. My water system is at 60 PSI and that is not my problem.

 

[Mister Twister]

As promised I am giving my results. I replaced the T&P valve with another new one this time from LOWES on Saturday morning. It is also a Watts but it is slightly different it has a little longer body. Same rating 150 PSI 210 deg F. No leaks as of this posting.

But the weird thing was my sidearm didn't seem to be doing its job at first. The water did not appear to be moving through it's normal thermo siphon or convection what ever you want to call it. Had to plug in the water tank and use some gas to heat water. So last night I cracked a union on top of the sidearm and took a shower to try and release any trapped air and now it appears to be working. Could it have been air locked from draining the tank and refilling it? What do you guys think?