Installed new Pressure Release Valve, vibration between 50-80PSI?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by JY2, Apr 15, 2019 at 9:37 PM.

  1. JY2

    JY2 New Member

    Orange County, CA
    Hello All,

    New member, looking forward to participating in this forum!

    I just replaced my pressure release value (Watts N45B M1) that was not regulating the pressure, it was reading nearly 120PSI. I replaced the part using a direct "drop-in", a Watts LF N45B M1. I used the original regulators fittings since it was compatible and simply used the new regulator and new gasket it came with.

    I left the pressure screw set to the default 50PSI and noticed when someone was using the shower, the pipes would vibrate loudly while the shower was on. When they turned off the shower, the loud vibration went away.

    Reading various posts on this forum I confirmed the water direction was correct on the regulator.. I took a photo of the old regulator before removing and confirmed the new part arrow is the right/same direction.

    On one post someone mentioned they liked to set the pressure to 70-90PSI so I adjusted the pressure screw to about 75PSI and turned on the shower. I noticed the loud vibration quieted down considerably, so I turned off the shower and increased the pressure to 80PSI. I turned the shower back on and noticed the loud vibration was just a slight humming sound now. I turned off the shower and adjusted the pressure to 85PSI. Now when I turn ON the shower I do not hear any sounds or vibration at all.

    My toliets still sound weird still after a couple of flushes, not sure if I just need to use them for a bit for the sound to go away..

    Do I have a bad regulator or did I install something incorrectly?

    Thank you for your advice,
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    There's a difference between a pressure release valve and a pressure reduction valve. Unfortunately, they both can use the same acronym. I assume you have a pressure reduction valve. Trying to use a pressure release valve could cause some issues.

    Do you get those noises with any other hot water use in the house?

    A PRV is on the incoming water line, and it should affect both hot and cold water use.
    WorthFlorida likes this.
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  4. WorthFlorida

    WorthFlorida Broad-Wing Hawk

    Oct 28, 2009
    Orlando, Florida
    Is there a drain valve near the PRV? You want find the source of the noise. Is it the PRV, the cartridge in the shower, a shutoff valve somewhere, possibly the water meter? By running water say to an outside spigot, do you get this noise? A drain valve would allow you to run water with the rest of the plumbing in front of it. If there is vibration then perhaps it is the PRV. If no, then something down stream is causing it. Changing the PRV I assume you turned off the water at the house entrance so that valve is now wide open. Check the shut offs at the water meter. Maybe someone many years ago closed one of them slightly to reduce pressure while the water was running.
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