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  1. #1
    Join Date
    Oct 2013

    Default High water pressure - new PRV and water expansion tank - still high

    Over several weeks, I would hear a high pitch noise after flushing some of our toilets in my house or using certain sinks. I checked my PSI - 120 to 140 psi. I changed out my PRV - noise stopped but pressure still too high. Valve installed correctly with the arrow in the right direction. I was told to check my hot water expansion tank - checked it and it was filled with water so I changed it out and set the new tank to 60 psi. I was all excited my problem was solved - unfortunately not. Pressure still reading at 120 to 140 PSI. Besides the pressure still being too high, I
    notice the pipe coming into my basement right before the PRV vibrates for several seconds when a toilet is flushed or water turned on. I am baffled - what should I do. Change out the new PRV to see if it is defective??

    Also, do I need to worry about my new expansion tank bladder rupturing since my pressure is still too high?

  2. #2
    Join Date
    May 2008
    Pacific Northwet

    Default Re: High water pressure - new PRV and water expansion tank - still high

    You didn't say that you tried adjusting the pressure regulator. Unscrewing the adjustment screw should lower the pressure; have a faucet open slightly when adjusting or you won't see the pressure drip.

    (BTW, the term 'PRV' usually means Pressure Relief Valve, which rather than regulating pressure opens to relieve excess pressure.)
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  3. #3
    Join Date
    Jul 2010

    Default Re: High water pressure - new PRV and water expansion tank - still high

    New pressure reducing valves are usually set at 50-70 when new. If yours shows 120, and you can't lower it, then something else is going on.

    If you are on city water, call your water company and ask then what the street pressure is. Also, ask neighbors if they have the same problem.

    Not knowing what you have, it's hard to suggest what to do. Call a plumber for an inspection.

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