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tnthvac 03-02-2008 08:37 PM

H2O htr
 
I have a gas hot water heater with a circulating hot water system, and the pressure temp. pop off keeps leaking water after the unit runs for a while. It has an expansion tank on it, any ideas on how to fix problem?

Mike Swearingen 03-03-2008 12:32 AM

T&P relief valves can go "bad".
Replace the existing one, and see if that doesn't solve the problem.
Good Luck!
Mike

tnthvac 03-03-2008 08:39 AM

Quote:

Originally Posted by Mike Swearingen (Post 103748)
T&P relief valves can go "bad".
Replace the existing one, and see if that doesn't solve the problem.
Good Luck!
Mike

It has been doing this since new, I have installed a pressure gauge on the spicket on the water heater and it varies from 55 psi water running and 120 psi after it sets for a while. What is the pressure relief set at on the valve, and could I have a bad pressure regulator on the main line? Thanks for your help!

End Grain 03-03-2008 10:07 AM

You might want to check the pressure of the cold water coming into the heater since it's probably very close to the main feed in your home. Here in AZ for example, outside pressure regulators are installed in many locations because of higher-than-normal or "boosted" line pressures so that homes in new developments that are farther away can also have water service. I carry a rather simple pressure tester that screws onto a garden hose bib, normally the one closest to the home's water main shutoff. Surprisingly, some of the line pressures on unregulated homes are often way up there, depending upon the time of the day and the water use. In the more serious occurences where no pressure regulator is installed or where it's become defective over time, copper tubes have split, PVC irrigation tubes have burst, toilet supply lines have ruptured, etc. Just a thought here before you get involved with the serious diagnostics.

Double A 03-03-2008 12:58 PM

Quote:

Originally Posted by tnthvac (Post 103796)
It has been doing this since new, I have installed a pressure gauge on the spicket on the water heater and it varies from 55 psi water running and 120 psi after it sets for a while. What is the pressure relief set at on the valve, and could I have a bad pressure regulator on the main line? Thanks for your help!

The T&P ( the one that keeps opening) is normally set for 150 psi and 180 degrees F.

It sounds as though you have one of two problems. The expansion tank is bad, or undersized or... the pressure regulator (the one on the main, incoming line) is failing.

On the expansion tank, you'll find an air fitting, like on a bicycle tire. Let a touch of air out. Did you get water out?

If so, you have a bad expansion tank.

When hot water is heated, it wants to take up more room. The expansion tank is two tanks in one, separated by a flexible bladder. Air on one side, water on the other. The air will compress and give the expanding water someplace to go other than out the T&P. If that bladder has failed, then the tank is completely filled with water and the system has no room to expand, so it opens the T&P valve to 'relieve' itself.

Hope this helps.

tnthvac 03-03-2008 08:08 PM

Thanks for the help I will try the pressure gauge on the cold water side and I will check the bladder tank and regulator, Thanks for the info!

Ron The Plumber 03-03-2008 08:23 PM

Quote:

Originally Posted by Double A (Post 103865)
The T&P ( 180 degrees F.

Thats 210 not 180

Double A 03-04-2008 01:31 AM

I stand rejected... erm, corrected.:laughing:


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