Pipes knocking in wall


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Old 04-26-16, 04:45 AM
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Pipes knocking in wall

Hello - Every time I run my washing machine or dish washer, the pipes bang when the water is shut off during their cycles. I've also noticed the toilets in the house also give a light bang when shutting off. I've had a water arrestor installed on the washing machine line but that hasn't helped. I have also had the whole townhouse water pressure adjusted to a safe, required level as well but the knocking continues. My questions are...

1. Is there anything I can do to stop the knocking of pipes? Would the walls need cut into in order to inspect and fix the knocking?

2. What's the likelihood one or more of the pipes could burst within the walls if this isn't repaired?

Thank you for all advice and help!
 
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Old 04-26-16, 06:26 AM
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You can install water hammer arrestors on your other problem fixtures. The type of arrestor can also have an impact. They come in different sizes. Small ones can work in mild cases but larger ones may be needed if the problem is more severe.

Depending on where the knocking is occurring you would have to open the walls to gain access and secure the pipes. If you're able to locate where they are banging you could try drilling a small hole into the wall cavity and inject expanding spray foam. Make sure you get the foam that expands. The stuff meant for doors and windows is low expansion (which you do not want).
 
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Old 04-26-16, 10:52 AM
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I've heard good things about the Watts hammer arrestors. I'm sure there are other decent ones out there, but if it's working correctly, once installed, it should resolve the issue at that fixture. You'll need additional arrestors at other fixtures.

It sounds like you solved the high pressure issue, that's usually the biggest issue. Do you know what your resulting pressure is? 80psi or less?

It sounds like either the pressure is still too high. It's not common to have the pipes banging that much all the time with all different fixtures.
 
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Old 04-26-16, 10:57 AM
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It is also very possible that where you hear the pipes banging they weren't fastened. I've used a small amount of spray foam to fix problems like that. The stud is located, a small hole is made next to it and then the nozzle is inserted into the wall. A few seconds shot of foam will expand and hold the pipes.
 
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Old 04-26-16, 02:46 PM
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Thank you!

Thank you all for the very helpful replies! It is much appreciated!!! Iím going to give your suggestions a try and Iíll let you know how it goes! Thank you again!
 
 

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