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Banging Hot Water Pipes

I have three bathroom sinks on the 2nd floor of my house. 1st and 2nd sinks are in the master bathroom, the 3rd sits in the other bathroom directly behind a wall (in other words, 2nd and 3rd sinks are separated by a wall). These two sinks separated by a wall experience loud banging. I think they are fed by the same hot water pipe because the 1st sink in the master bathroom never has this problem. The problem occurs about 1-2 minutes after running the hot water faucet: the pipes start banging behind the walls. It is deafening. Under one sink I can even see the hose feeding the faucet from the hot water valve literally jumping up and down. FYI this never happens with one sink in the master bathroom, nor any of the two showers on the 2nd floor. Only the 2 sinks separated by a wall. It stops immediately after shutting off the hot water. I investigated in the basement as well. When running the hot water from those 2 sinks I feel the vibration above the hot water heater, but don't think it's related to that site (it doesn't happen at any other sink in the house).

How do I fix this? From what I can see behind these two sinks, the pipes look pretty well tethered to the joists. I don't see any vibration except at the hose, but know the hose can't be making all that noise. How do I fix this without tearing up my entire 2nd floor walls?

If I can't fix it, and just decide to live with the annoying jackhammering, does this set me up for damage down the line to my pipes in 5 or 10 years? Do I have to fix it?

Re: Banging Hot Water Pipes

Try tightening the pipes to the house framing in a better way. I still think that the pipes are causing the noise when they get hot. Removing some drywall is necessary, then blocking and strapping.

Re: Banging Hot Water Pipes

:) Thanks. It looks like the previous homeowners did have to rip into the walls at some point bc I see a small area of them probably trying to color match the paint at a patched up site, likely over where the banging is loudest. is this typically something that needs to be fixed and re-adjusted every few years or so? what is the harm to the house if I just leave it alone? any risk of burst pipes? :(

Re: Banging Hot Water Pipes

Banging pipes happen from one of three sources;

1- air trapped in the pipes (hammering) which is solved by installing arrestors

2- pipes attached too firmly to the studding so that when the pipes heat and expand, the brackets release and grab the pipes alternately (sounds like your problem)

3- Pipes too loose, hanging in the air

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