Wall Knocking

Old 03-12-22, 12:06 PM
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Wall Knocking

My hot water heater started knocking so I took step to clean it.
Turned out the knocking was coming from inside a wall.
I have a wall that separates my 2 from my 3 car garage.
The previous owner took a water softer with them when they sold the place, the piping is still there for it.
That piping runs back inside the wall down low. Turns out the knocking is inside that wall when pressure is relieved/water is in use inside the house.
What would be in the wall to cause this?
Old 03-12-22, 12:12 PM
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Water cavitation can cause unsecured pipes to move. The solution would be to open the wall and either remove or secure the pipes with clamps so they can't move.
Old 03-12-22, 07:10 PM
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Another solution that I've used in the past is identify in the wall where the knock is coming from.

Make/drill a small hole large enough to get the extension hose in from a can of spray foam and give it a five second squirt. Easy enough to fill the hole back in and touch up. You'll want to use non-expanding foam so as not to blow the wall open. The foam will stop the knocking if you get it in the right place.

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