Pressure creep with bad PRV

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by santhon2, Jan 26, 2014.

  1. santhon2

    santhon2 New Member

    Messages:
    5
    Location:
    Georgia
    I have major water pressure creep all the time. New water heater installed with expansion tank and the pressure is being relieved by the pressure release valve. I have tested the lines with a pressure gauge and the flow is regulated at 40-50 psi when running. The gauge registers a high of 150 psi over night which triggers the release valve. I have tested the line with the water heater turned off so I know it's not thermal expansion. My question, is the pressure regulator valve on the incoming line supposed to shut off the inlet when the line pressure reaches the set psi at say 50 or do they usually allow the pressure to continue? Do I need a different valve to keep out the higher pressure? I am the last house at the end of the street and I believe the water main ends here and does not continue. Not sure if the pressure regulator valve is bad as it does regulate when running. Thanks for the help.
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,413
    Location:
    Bothell, Washington
    You need to either install a rebuild kit to your PRV, or replace it.
    Most of the time, we replace the PRV, mainly because we can do that in one trip. You could look up the tag on your unit and see if parts are available.
  3. santhon2

    santhon2 New Member

    Messages:
    5
    Location:
    Georgia
    But, does the PRV shut off the water when the system is pressurized at the set psi or continue to allow creep? Or is that a different valve?
  4. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,508
    Location:
    Houston, TX

    If it is bad, It is hard to tell what it may do.

    But it will most likely still pass water, and not regulate.
  5. santhon2

    santhon2 New Member

    Messages:
    5
    Location:
    Georgia
    I guess I'm noting asking the question right. Will a NEW pressure reducing valve keep the water pressure at the set psi or do they still allow creep? When the system is fully pressurized at 50 psi does the prv hold back the additional pressure if the incoming is 150 psi or higher or do i need something else?
  6. Terry

    Terry Administrator Staff Member

    Messages:
    15,413
    Location:
    Bothell, Washington
    That's what it does. It keeps the pressure at that setting, unless there is thermal expansion. That's why you also have a thermal expansion tank.
    You mentioned that with the water heater turned off, that the pressure climbs to 150 PSI, up from 50. You have a bad PRV
  7. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,508
    Location:
    Houston, TX

    A good working one will stop the flow of water at the preset limit.

    Is your expansion tank pre-charged properly ?


    Good Luck.
  8. santhon2

    santhon2 New Member

    Messages:
    5
    Location:
    Georgia
    I charged the expansion tank to 60 psi, didn't help. So until i get a new prv installed should i turn off the water at night and during the day when there is no one here or just let the pressure valve on the water heater take care of it?
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    It's kind of unusual for the supply pressure to be in excess of 150psi, but it can happen if you're close to the pump or water tower, or sitting at the bottom of a big hill. But, if it is, check the specs on the PRV you are using. Most can handle that pressure differential, but some might require a second one in series to drop the pressure incrementally. Have you measured your supply pressure?

    To check and adjust the expansion tank, you must turn the water off, open a faucet to relieve any pressure, then you can check and adjust the pressure in the ET, otherwise, you are just checking the water pressure in the system.
  10. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,508
    Location:
    Houston, TX
    I do know that 150 psi will test your plumbing for weak points.

    It will also check Appliances and water fill valves.


    I would kill water when not at home, until you can get it fixed. That should be ASAP.
  11. dj2

    dj2 Member

    Messages:
    437
    Location:
    California
    Regulators go bad every once in a while. If you know how to fix them and have the time to do it, call the manufacturer for a kit. Otherwise, replace it, which is quicker and I bet cheaper.

    Like was said before, if you leave the house, shut the water. You don't want to come home to a flood.
  12. Reach4

    Reach4 Well-Known Member

    Messages:
    2,793
    Location:
    IL
    How fast does your water pressure creep up? You maybe able to work around this for a few days by opening a cold water tap to a veryslow trickle until you get the repair.
  13. santhon2

    santhon2 New Member

    Messages:
    5
    Location:
    Georgia
    Pressure creeps up pretty fast when it isn't being used, the 150psi is only what I gauged it at before the relief valve worked, it could be more. No leaks anywhere else at that pressure.
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