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!

  • @im_mr_clean
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    131 year ago

    Sounds like “water hammer”. If you google that others can give a way better explanation of why it happens.

    I fixed mine by closing the main at the street, and opening the faucet highest and furthest from the main. In my house that was an upstairs faucet at the opposite corner from the main. Released all the pressure and then turned back on the main. Noise left and hasn’t come back for 6~ months. There are knock arresters you can install or have installed that stop the problem before it happens.

    • @h0rnmanOP
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      31 year ago

      So I’ve already done this one. Exactly according to the link posted a bit further down but no dice. I’m really confused as to why this only seems tied to the hot water though