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  1. #1
    Join Date
    Sep 2008
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    Default New Expansion Tank/T&P Valve Still Leaking

    Our T&P valve has been leaking for months. We would just turn the cold water off to the water heater to get it to stop. We finally had our landlord install an expansion tank. It's installed, but the T&P valve still leaks continuously. The pressure coming into the house is 40 psi. I checked the pressure on the tank - it's also 40 psi. The expansion tank fills up as the water heats and expands, and when it's full, the T&P valve leaks until we use some hot water or turn off the cold water to the heater. Any thoughts?

  2. #2
    Join Date
    Jun 2007
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    Fayette County, Ohio
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    Default Re: New Expansion Tank/T&P Valve Still Leaking

    Bad T&P valve or dirt in the valve. Try opening and closing it a couple of times to see if it flushes out dirt, if not replace valve.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #3
    Join Date
    Sep 2008
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    Default Re: New Expansion Tank/T&P Valve Still Leaking

    I forgot to say that this is the second valve for the water heater - I tried that before anything else. It's been flushed several times over the past few days. Should I get a new valve? Could it be anything else?

  4. #4
    Join Date
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    Default Re: New Expansion Tank/T&P Valve Still Leaking

    When you say that the tank pressure is also 40psi...do you mean you checked the air pre-charge and it was 40 psi?

    Have you tried depressing the air fill valve on the expansion tank when the T&P is leaking? If water comes out then it means that the internal bladder is faulty/has a tear in it... and there is no air cushion. Just a quick tap on it should tell you. The longer you hold it down, the more air pre-charge you will lose if it still has a pre-charge in it.

    The problem may prove to be in the T&P though, as Jack suggested.

    Am also curious as to when/why this problem first began. Was something changed and then the problem suddenly appeared? City installed back-flow preventers on the water lines, maybe?
    Last edited by goldhiller; 09-15-2008 at 11:39 PM.

  5. #5
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    Default Re: New Expansion Tank/T&P Valve Still Leaking

    40 psi should be absolutely no problem, I beleive the specs for a T&P valve is to release between 124 and 150 psi and 210 degrees F.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  6. #6
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    Default Re: New Expansion Tank/T&P Valve Still Leaking

    or the temperature is set too high on the tank and the T&P is doing it's job.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  7. #7
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    Default Re: New Expansion Tank/T&P Valve Still Leaking

    Quote Originally Posted by JLMCDANIEL View Post
    40 psi should be absolutely no problem, I beleive the specs for a T&P valve is to release between 124 and 150 psi and 210 degrees F.
    Jack
    Understood. What I'm wondering is when was the pressure checked. Maybe the tank had no precharge at all. Ya never know.

  8. #8
    Join Date
    Jun 2007
    Location
    West Jordan, Utah
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    84

    Default Re: New Expansion Tank/T&P Valve Still Leaking

    Do you have any other appliances or connections to your water lines that may be causing the excess pressure? Maybe the water heater isn't the problem, it is just the point where the pressure is relieved.

  9. #9
    Join Date
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    Default Re: New Expansion Tank/T&P Valve Still Leaking

    Quote Originally Posted by Blake View Post
    Do you have any other appliances or connections to your water lines that may be causing the excess pressure? Maybe the water heater isn't the problem, it is just the point where the pressure is relieved.
    Interesting notion.

  10. #10
    Join Date
    Sep 2008
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    32

    Default Re: New Expansion Tank/T&P Valve Still Leaking

    Do you have any other appliances or connections to your water lines that may be causing the excess pressure? Maybe the water heater isn't the problem, it is just the point where the pressure is relieved.
    Nope. There are no other heat or pressure producing appliances hooked up to the water line.

    It sounds like the options here are to either:

    1. Get a new water heater to eliminate the possibility of a broken thermostat or heating coil that won't shut off (and make sure there are no heat traps or check valves in the new heater)

    or

    2. Get a new PVR that permits backflow into the city system (assuming the city system is less than 140 PSI)

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