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  1. #1
    Join Date
    Oct 2010
    Location
    Massachusetts
    Posts
    6

    Post Water Heater Temp/pressure valve leak

    I have a gas fired stand alone water heater that leaks when water is being heated. I checked my water pressure at the inlet to the house and it is fine and the temp is set at 140 degrees. I installed a new valve and I have the same problem.

    Do I need an expansion tank or something like that?

  2. #2
    Join Date
    Feb 2008
    Posts
    554

    Default Re: Water Heater Temp/pressure valve leak

    When you say it "leaks" I take it you mean it's leaking out of the throat of the new valve you just installed.

    A water temp setting of 140 degrees is a shade high to set it & could scald someone taking a shower; try reducing down to 130 or so to see if there's any change.

    Has the leak been of recent origin, or has it been leaking for some time???

    First check the tags on the new & old valve to make sure you installed the correct valve.

    Typical pressure relief valve setting is 150 lbs psi.

    Typical temperature relief valve setting is 210 degrees.

    These values should be stamped on the little tag on the old valve as well as the new valve.

    In other words, the water temp the water heater is making can't exceed 210 degrees and the house water pressure can't exceed 150 psi.

    Please post back with the brand name & model numbers of both valves, and the results you got for the house water pressure.
    Last edited by NashuaTech; 10-18-2010 at 02:35 PM.

  3. #3
    Join Date
    Feb 2010
    Location
    South*East
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    1,208

    Default Re: Water Heater Temp/pressure valve leak

    You need a thermal expansion tank. When the water is heated it expands causing the T&P valve to open. The valve is doing it's job. 140 degrees is also to hot.

    John

  4. #4
    Join Date
    Feb 2008
    Posts
    554

    Default Re: Water Heater Temp/pressure valve leak

    Hot water heaters supplying a domestic hot water circuit ordinaily don't need a thermal expansion tank; any rise in pressure due to expansion is partially absorbed by the piping & small amount of air in the top of the HWH; the rest of the pressure is backed up thru the water main out into the street main.

    The exception is when a check valve (anti-backflo valve) is installed at the water main--in such cases they are usually required by code.

    Sometimes the water main pressure can vary quite a bit between daily peak usage & overnight off-peak; this can create problems with varying pressure spikes in off-peak periods.
    Last edited by NashuaTech; 10-19-2010 at 12:55 AM.

  5. #5
    Join Date
    Dec 2008
    Location
    Midwest
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    173

    Default Re: Water Heater Temp/pressure valve leak

    Just wondering what type of WATER HEATER has air in the top? This sytem needs a therm expansion tank. Period!

  6. #6
    Join Date
    Feb 2008
    Posts
    198

    Default Re: Water Heater Temp/pressure valve leak

    Quote Originally Posted by MSSP View Post
    Just wondering what type of WATER HEATER has air in the top? This sytem needs a therm expansion tank. Period!

    Well, we still haven't heard from the OP as to why all of a sudden something's changed after all this time & the valve is leaking.

    It's just sloppy troubleshooting procedure to shoot off your mouth & insist on additional components & expense when the system may or may not need them----how about throwing in a new boiler while we're at it???

    I agree with Nashua.
    Last edited by Dobbs; 10-20-2010 at 09:16 AM.

  7. #7
    Join Date
    Oct 2010
    Location
    Massachusetts
    Posts
    6

    Thumbs up Re: Water Heater Temp/pressure valve leak

    I installed the expansion tank this past Saturday. The leak has stopped and everything seems to be working properly.

    Thank you everyone for all your help.

  8. #8
    Join Date
    Dec 2008
    Location
    Midwest
    Posts
    173

    Default Re: Water Heater Temp/pressure valve leak

    Gator12 Glad to hear your leak is over. Post a pic for all to see your work and enjoy some relaxation time. Glad we all could help
    Last edited by MSSP; 10-25-2010 at 07:34 PM.

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