Pressure Relief Valves Won't Stop Leaking

Discussion in 'Water Heater Forum, Tanks' started by niteowler, Apr 2, 2009.

  1. niteowler

    niteowler New Member

    Messages:
    6
    I Recently replaced my hot water heater with exact same model as I had before. However after I installed the new water heater the pressure relief valve began to leak. Both water heaters are table top water heaters with the pressure relief valve located on top of the water heater directly in the center. The old heater pressure relief valve wasn't even piped. I could tell by the lack of any water stains of any kind that the pressure relief valve had never leaked or if so very little.
    I called the manufacturer after the new water tank's pressure valve began leaking and fortunately they sent me a new one. Replaced it and piped it up according to the manufacturers specifications six inches above the floor. It also leaks about 1 to 2 cups of water daily. Turned the water pressure down to the point where the water barely ran and it still leaks. Also turned the water temperature down to 120 degrees with the same result. Two exact same water heaters with the exact same setup except the new heater pressure relief valve is piped (like it should be) and it won't quit leaking. At this point I don't know. Any comments is greatly appreciated.
  2. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Have you got a thermal expansion tank?
  3. niteowler

    niteowler New Member

    Messages:
    6
    I don't have a thermal expansion tank but I may have to consider one if it doesn't stop leaking.
  4. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    What is your water pressure?

    Do you have a pressure reducing valve?
    Usually they are near the meter and look like this...

    [​IMG]
  5. niteowler

    niteowler New Member

    Messages:
    6
    I don't know what the pressure is now but i turned the pressure reducing valve down to the point where the water barely ran in the house to see if that would help. The pressure relief valve still leaked to my amazement. I turned it back up since it didn't help and the pressure was to low to even be useful.
  6. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,395
    Location:
    Yakima WA
    There is a very simple answer to your problem. You must install an expansion tank. This pressure regulator valve has a check valve internally that prevents the expansion from the water heater to be absorbed by the city water main. When the pressure reaches the limit of the pressure relief valve, it does exactly what it is supposed to do. It trips to relieve the pressure. Along with this, you need to get a pressure gauge to set the pressure regulator to somewhere around 60 psi. Then set the air pressure in the expansion tank to just a shade less than 60 psi. Use a small hand air pump for this. The expansion tank installs in the water supply line between the pressure regulator and the water heater. It must be well supported.
  7. ChuckS

    ChuckS New Member

    Messages:
    96
    Location:
    Aurora, CO
    I never understood this, why do you set it a tad below normal pressure? My simple mind thinks it would stay full if you set it a tad below. I wanted to set mine a tad above normal pressure thinking it will only take in water as pressure rises.

    I took mine to grease monkey and had them run the air up to max. I was then able to release the air to the needed level before I installed it.
  8. bad prv valve

    you probably have a bad pressure reduceing valve...

    allowing the pressure to rise over time to whatever the incomming pressure is.. and then the pressure rises as the water heats till it hits the point the t+p valve weeps...

    get a new one and put in the larger expansion tank somewhere in the system near the heater if possible..

    my opinion on it all is to set the desired pressure you want everythign to be at, like 70 lbs on your new PRV valve, , then set the expansin tank at about 85 psi...,,, then anything above that will rise into the expansion tank and not trip off the prv valve which usually is set at a much higher level...... like I dont know exactly somewhere around 150??

    of course these settings will be debated....
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,251
    Location:
    Cave Creek, Arizona
    leak

    Guessing will never solve your problem. First you have to determine why the valve is leaking. Whether it is leaking continually or periodically, since they are signs of two different conditions. Also, the amount of water which leaks, if it is intermittent, is relevent.
  10. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    You possibly have a bad new T&P valve...you may need someone who knows how to corectly diagnose the problem...possible problems are a bad...

    T&P

    Pressure Reducing valve

    bad Thermal Expansion Tank

    Or needing to install a Thermal Expansion Tank

    Or some combination...

    [​IMG]
    T&P Valve looking at two sides.
    Last edited by a moderator: Apr 24, 2009
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,316
    Location:
    New England
    A couple of cups after a large hot water use is probably correct to account for heating all of the cold water that replaced the original hot...get a pressure gauge and install an expansion tank (or replace the bad one if you have one already) and you'll probably solve your problem. The gauge will tell you what's happening, so that's your first task. Plain fact...water expands as you heat it...pipes don't (at least not to the same degree), pressure rises, it leaks at the weakest point. With a PRV, that's in the house, without one (or a check valve), it pushes back into the main from the street (which is why they don't like it - you could be inserting pollutants if your plumbing was compromised into the public system).
  12. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,395
    Location:
    Yakima WA
    He has a new tank that had a new T/P and that leaked. He got another T/P from the factory and that leaked. He doesn't have a thermal expansion tank, but he does have a PRV. He has changed the T/P with no success. Could he have a bad PRV? Yes, but that would not cause the T/P to trip. This sure sounds like thermal expansion to me, and even if the PRV ends up being bad too, he still need an expansion tank in a closed system.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,251
    Location:
    Cave Creek, Arizona
    T&p

    The old T&P may not have leaked, even if it should have, because it was corroded and could not operate. That is the reason to test a T&P periodically and replace it if it does not shut off properly.

    [​IMG]
    T&P Valve looking at two sides.
    Last edited by a moderator: Apr 24, 2009
  14. niteowler

    niteowler New Member

    Messages:
    6
    I would like to think everyone for their well thought out and knowledgeable comments. This water heater problem is actually my neighbors. She is 88 years old and lives by herself and her close family members live many states away. I try to help her as much as I can if she needs it. Hopefully I will be taking her to town soon to get an expansion tank and water pressure gauge and it solves the problem. Thanks for your great advice!
  15. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Get just the pressure gauge. Post back with a water pressure reading.
  16. niteowler

    niteowler New Member

    Messages:
    6
    I connected a water pressure gauge inside the house and it read 107 psi. Whoa! Turned the water pressure down on the PRV to the point where the water barely ran. With the water running it read 10 psi and when i shut the water off it crept back up to at least 100 psi. Looks like the PRV is probably the culprit.
  17. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Not sure how you couls do that as most PRVs have a minimum setting of 25 or 35 PSI try replacing it...how did you turn it down...did you use a screw driver or a wrench or did it have a handle???
  18. niteowler

    niteowler New Member

    Messages:
    6
    Replaced the PRV and everything appears to be fine now. A friend of mine says he has lived in his house now for 20 years and he is on his third PRV. I didn't know they went bad very often.
  19. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,395
    Location:
    Yakima WA
    Any device manufactured by man will fail in time. This has nothing to do with country of origin, brand, cost, or anything else. The point you must understand is that when you have a PRV in a home, you must also have a Thermal expansion tank. To see for yourself what the problem is, adapt a pressure gauge to a faucet connect it to a hot water faucet in the home. Drain hot water until the heater begins to heat. Open the faucet with the gauge attached and watch the temperature rise. If that doesn't make the convince you of the need for a thermal expansion tank, nothing will.
Similar Threads: Pressure Relief
Forum Title Date
Water Heater Forum, Tanks Water heater leaks out pressure relief valve Apr 30, 2014
Water Heater Forum, Tanks Temperature Pressure Relief Valve (TPR) re-location? Apr 17, 2014
Water Heater Forum, Tanks Water Heater pressure relief line covered by concrete Jul 3, 2013
Water Heater Forum, Tanks Necessity of Vacuum Relief Valve - Not Pressure Relief Valve Oct 23, 2012
Water Heater Forum, Tanks Water Heater Pressure Relief Valve Leaked About a 2 Quarts of Water Jul 2, 2009

Share This Page