Home Improvement Stack Exchange
Home Improvement Stack Exchange

Questions tagged [water-hammer]

Finding and fixing the causes of water hammer, a shuddering, knocking or banging noise in water pipes.

Water hammer is a shuddering, knocking or banging noise in water pipes, caused by sudden changes in the speed of the water flowing in the pipes.

In the home, washing machines and dishwashers are often the culprits because they have electromechanical valves that open and close very quickly on their water supply lines. It can also occur in the supply lines for toilets.

Related tags:

  • for general plumbing related questions. If you're asking a question about water hammer, it's probably appropriate to include this tag too.

External references

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How do I fix a "water hammer" problem?

When I shut off a water faucet or right after the toilet tank refills after flushing, I hear a vibrating sound in my pipes. It last between one and two seconds. On the interwebs, I found out that it's called "water hammer" and that it can be fixed…
vitule
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Can I reduce or eliminate water hammer without plumbing?

I have a friend who lives in an apartment with terrible water hammer problems which the management is unwilling to fix. I'm curious if there is a product or device that would attach, for instance, to a faucet with the faucet on that would act as a…
Adam Davis
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What's the science between the double pipes behind washer feed?

I opened up the wall to relocate my washer's water feeds and discovered an interesting double pipe arrangement. For each of the cold and hot feeds, there is an extra arm/appendix about 3feet long that dead-ends into an end cap. What's that for? I'm…
init_js
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How can I stop the loud banging sound in my water pipes when using my clothes washer?

We just bought a townhome and every time we use the LG Front loading washing machine there is a loud bang throughout the pipe system. I checked the back and there are already 2 water hammer arrestors (Size AA) installed on the inlet to the washing…
Larry L
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Vacuum Breaker Valve on Hose Bib Humming / Noise

I have one of these vacuum breakers on my outdoor hose faucet. Every time I turn it on, it creates a loud noise in the form of a hum or drone I can hear throughout the house. While I have been able to find many similar questions on the web, as good…
HodlDwon
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Laundry box and water hammer arrestor

I am trying to install my new washer & dryer combo. There are a few things that I am not sure since plumbing hardware and markings are a bit different in the US compared to once I used in Russia. Please take a look at the photo and help me figuring…
Igor Soloydenko
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Water hammer or something else?

I'm having a bit of a mysterious problem. A couple of weeks ago I've replaced a dimmer switch in the upstairs bathroom. Of course while working on that I shut off the electricity for that part of the house. Since turning it back on we've been…
Ruben
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How can I locate and eliminate mysterious water hammer related to humidifier?

In the morning, early, when my thermostat kicks back up, I hear a banging/rattle sound that I've determined is related to my humidifier. It only lasts about 10 seconds so by the time I get down to the basement it's gone. Turning on/off the…
Andrew
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Why does my Rinnai Infinity water heater fire up after turning off the cold tap?

I have a Rinnai Infinity XR20. It's about 3 years old. I've just recently noticed a peculiar issue with it that I hadn't noticed before. If I turn on a cold tap like the one to the garden hose and then turn it off, the unit momentarily…
hookenz
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What causes hammering from a new diverter when other faucets are quickly turned on and off?

We're doing a minor remodel of our master bathroom, and I have replaced the 30+ year old diverter and nearby pipe with a new one from Delta. Now when any faucet in the house is turned on and off quickly, there is a hammering or banging sound coming…
joshdoe
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How can I stop pipes from vibrating / rattling / hammering after a new pressure valve was installed?

I tested the water pressure last month and it came up at 89psi. My old pressure regulating valve said it would only go to 75psi and turning the bolt didn't change the pressure, so I assumed it was shot and replaced it. No leaks and the new valve…
pennstump
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Is this water hammer? Why are my dead legs not helping?

I live in Houston, where we had a severe freeze a few months ago. I opened a bunch of faucets to drip, but one of my pipes (above a master closet) still burst. That forced me to turn off the water and drain some sections of pipe to patch the hole…
John Freeman
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How to stop whole house water hammer?

I am in a newly built house (completed in 2020). For the first 8 months or so, the plumbing worked great. We had a toilet gasket warp and so the tank would slowly leak, and I started noticing a persistent thunking every time that tank…
eerick
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Why does my water hammer arrestor ask for 5psi less than house pressure and not 10 psi or 20 psi?

I have Watts LF150A water hammer arrestors attached to the hot and cold supply valves for my washing machine (my LG washer is crazy about the water hammer). The LF150A instructions say to add pressure in the valve that is 5 psi less than the house…
Anthony
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Is the operation of a hard-start domestic water pump improved by the addition of an external soft-start controller?

I have a ½ HP 115V/230V 1PH 60Hz water pump (inside my house) that starts and stops hard. It is connected to a simple on/off pressure switch. The noise at startup is jarring. The quarter-turn ball valve shutoff between the supply and the pump has…
Jean-Paul Calderone
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