T&P Valve Leak

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Mikeyboy, Nov 29, 2008.

  1. Mikeyboy

    Mikeyboy New Member

    Messages:
    45
    It all started when my T&P valve started leaking so I replaced our expansion tank with a Wellsaver expansion tank from Lowes left it pre-charged at 25psi. Result - still leaking but less

    Then, I replaced the T&P with a new one. Result - still leaking but a lot less

    Then, I realized that my old expansion tank was a Watts that was pre-charged at 40 psi. So, I turned off the water and power from my 50 gal electric wh, released all pressure from from the T&P valve, added air to the expansion tank to 40psi. Result - still leaking but a lot less.

    Then, I bought a water pressure guage and connected it to the cold laundry side and here are the results:

    1) When I turned on the water, the gauge jumped to about 140 psi. When I open the faucet, the pressure drops but when I close the faucet the pressure slowly creeps up to 140psii.

    2) When all the pressure was released, I added more air to the expansion tank to approx 55psi where initially it had about 40psi. When I turned on the water again, the gauge went back to approx 140 psi.

    So, what is wrong? Is my expansion tank not working? Is it too small? I called the town and they did not increase any water pressure. Please keep in mind, this was all working fine with no drips a few months ago. The only thing we did within that time is winterize and blow our irrigation system but we do that at the end of every summer.

    I also I have a pressure reducing valve after the water meter that looks old. Should I try loosening the check nut on the prv counter-clockwise to hopefully lower pressure?
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,263
    Location:
    Cave Creek, Arizona
    tank

    The pressure in the tank is completely irrelevent as long as it is less than the relief valve setting, but normally it is set to the static pressure in the system. You have a defective pressure reducing valve, and the expansion tank has nothing to do with preventing that pressure increase.
  3. Mikeyboy

    Mikeyboy New Member

    Messages:
    45
    How can I verify it is the prv?

    Is there a way to repair it?

    Should I try loosening the check nut on the prv counter-clockwise to hopefully lower pressure?
  4. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    The fact tht you have 140 lbs pressure that drops considerably when you open the faucet verifies the PRV is bad. No they can not be rebuilt, must be replaced.
  5. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Not sure what brand of PRV you have but some of them do have rebuilding kits you can get...It may be difficult though to find one...it is normaly easier to replace them...
  6. Mikeyboy

    Mikeyboy New Member

    Messages:
    45
    If I need to replace the prv, do I have to put it in the same place right after the water meter? I had an irrigation system put in a few years ago and I was wondering if the new prv can be put in after the outgoing pipeline for the irrigation system so I can have increased water pressure for my springkler system?
  7. Terry

    Terry Administrator Staff Member

    Messages:
    15,419
    Location:
    Bothell, Washington
    What pressure do the irrigation controls handle?
    Most plumbing requires a pressure reducing valve for anything over 80 PSI
  8. Mikeyboy

    Mikeyboy New Member

    Messages:
    45
    Is it normal for the check nut on the prv to be completely tight like it was closed all the way? I have never touched this since we moved in over 2 years ago.

    I loosened it a lot, then closed the cold laundry faucet and waited for water pressure gauge to drop to zero. Once it hit zero, I turned on the laundry faucet and the pressure jumped to 60 psi instead of 140psi when the check nut was completely tight.

    Is this normal? Is the prv OK? What else can I check?

    When I open the cold water in a regular faucet, the pressure gauge drops to 30 - 40 psi.

    I will now wait to see if the gauge will go higher than 60 when no faucet is in use.
  9. Terry

    Terry Administrator Staff Member

    Messages:
    15,419
    Location:
    Bothell, Washington
    [​IMG]
    TO READJUST Pressure, loosen check nut and turn adjusting screw clockwise to raise pressure and counter clockwise to lower pressure.
    The use of a water pressure-reducing valve normally creates a closed system. When water is heated in a closed system, it expands, causing an increase in pressure. This pressure may increase to the set pressure of the relief valve (on the water heater) causing it to drip, thus releasing the expanding water and protecting the system against excessive pressure, This increase in the system pressure over that regulated by the reducing valve is called "thermal expansion pressure".

    http://www.watts.com/pro/_productsFull_tree.asp?catId=64&parCat=285&pid=776&ref=2
  10. Mikeyboy

    Mikeyboy New Member

    Messages:
    45
    But how will I truly know if my prv is working or not?

    What tests can I do?
  11. Terry

    Terry Administrator Staff Member

    Messages:
    15,419
    Location:
    Bothell, Washington
    That's a little hard to do.
    With Thermal Expansion, you will have some elevation of the pressure.
    The expansion tank is supposed to take care of that.

    Normally I would set the pressure for 60-65 psi to start.
    If it jumps up to 80 and more, you may have a problem with the prv

    If the prv is more than 10 years old you may have a problem.

    I've seen some older PRV's that keep the pressure lower, but have no volume. They don't run two faucets at the same time with enough pressure to keep the diverter on the tub to pressure up to the shower head.

    [​IMG]
  12. Mikeyboy

    Mikeyboy New Member

    Messages:
    45
    I woke up this morning with the pressure gauge at 70psi so will we assume that the prv is doing its job? The only problem I see is that when I was taking a shower and my wife was using the faucet in the kitchen, you can feel the pressure in the shower dropped. I will have to test the pressure with two showers running at the same time.

    I examined my pipes in the basement and they are on the smaller side so is that why I need more pressure to compensate for the small pipes. What psi should I keep the water pressure at to keep the people in the house happy and still prevent any damage on the water heater, expansion tank, pipes and yeah prevent the t&p from spitting?
Similar Threads: Valve Leak
Forum Title Date
Plumbing Forum, Professional & DIY Advice How to test a tub/shower valve body for leaks Nov 3, 2014
Plumbing Forum, Professional & DIY Advice Shut off valve leaking Aug 24, 2014
Plumbing Forum, Professional & DIY Advice Can i service stem which appears to be source of leak in watts ball valve? Feb 22, 2014
Plumbing Forum, Professional & DIY Advice Temporary fix for ball valve leaking since handle sheared off? Dec 14, 2013
Plumbing Forum, Professional & DIY Advice Tiny leak into bowl, but already changed flush valve and flapper Sep 12, 2013

Share This Page