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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
    550

    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 01:35 PM.

  3. #3
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,168

    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
    550

    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; 10-18-2010 at 11:55 PM.

  5. #5
    Join Date
    Dec 2008
    Location
    Midwest
    Posts
    158

    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
    175

    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 08:16 AM.

  7. #7
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,168

    Default Re: Water Heater Temp/pressure valve leak

    Quote Originally Posted by Dobbs View Post
    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.
    The reason may be that a back flow device or a PRV has recently been installed.
    John

  8. #8
    Join Date
    Jul 2009
    Posts
    137

    Default Re: Water Heater Temp/pressure valve leak

    Quote Originally Posted by johnjh2o View Post
    The reason may be that a back flow device or a PRV has recently been installed.
    John

    Until we hear from Gator we don't know WHAT is going on there.

    Sounds like Gator is just playing games with us.

    I go along with Dobbs, and recommend a new water heater AND a new boiler, AND a new expansion tank.

    I'd also replace the cold water piping back to the street shutoff.
    Last edited by Pelton; 10-20-2010 at 02:17 PM.

  9. #9
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,557

    Default Re: Water Heater Temp/pressure valve leak

    I'm closing in on seventy years of age, have lived in several homes, and gone through I don't know how many water heaters but have never had to install an expansion tank. I have also never seen NashuaTech give false or misleading advice.

    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  10. #10
    Join Date
    Dec 2008
    Location
    Midwest
    Posts
    158

    Default Re: Water Heater Temp/pressure valve leak

    Quote Originally Posted by Dobbs View Post
    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.
    Well there dobbs why do you say I am shooting off my mouth? I am going off the fact that he had this problem and then put in a new T&P and still has the problem.If this is a closed loop system with or with out a check valve IT NEEDS AN EXSPANSION TANK. I am not trying to sell a boiler or a new heater. I am just giving my opinion. I also have never seen a water heater hold any air in the top to absorb any pressure or temp elevation. I do have 26 yrs of plumbing experiance under my belt.

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