I have a very odd issue that I can’t solve, perhaps someone here could help. The pipe attached to my main shutoff valve is emitting a soft knocking sound at around 120 beats per minute. The sound persists as long as there is any amount of pressure, and I can feel it in the pipe nearby as well as in the valve handle itself. The weird part is that if I turn on any hot water tap, the noise vanishes. I’m a new homeowner so I don’t have much experience, so any help would be appreciated. What I’ve checked so far:

Drained the system completely and refilled

Turned the water off overnight and checked toilets for leaks

I don’t feel the pulse at the water meter line

Turning hot water on anywhere in the house stops the noise.

Thanks in advance!

  • @ttenborough
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    31 year ago

    Do you have a PRV? Is the sound worse at the PRV?

    The hot water flow making the sound go away isn’t explained by a bad PRV but everything else could be.

    • @h0rnmanOP
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      11 year ago

      PRV? Not sure what that is or where i would find it

      • @nowwhatnapster
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        11 year ago

        Pressure reducing valve. Typically found directly after the water meter to reduce high municipal water pressure to reasonable residential water pressures.