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Waterhammer

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dik

dik

Structural
Apr 13, 2001
26,072
We live in a 2 storey home with washrooms upstairs and downstairs. In the last week, we have a waterhammer noise that continues until a tap in the washroom to allow water to run.

Can anyone suggest the cause of the waterhammer 'buzz' and a means of stopping it, or even where to try? It is just recent event, but, is annoying.

Dik
 
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If you have an expansion tank on your water heater, I'd start there. Make sure it is functional.
 
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I don't think I do, but, I'll check.

Thanks, Dik
 
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"In the last week, we have a waterhammer noise that continues until a tap in the washroom to allow water to run."

"Waterhammer" is not a continuous thing, and in a typical house, it's more of an echo of the valve being closed, given the speed of sound in water.

What's initiating the noise? Have you tried changing the speed of closure of the valve?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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did it just start recently ?

there are lots of plumbing add-ons for removing water hammer ... google "water hammer prevention"

another day in paradise, or is paradise one day closer ?
 
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Does your air handler unit drain to the same location as that sink in the washroom?

I ask because in my current house, my AHU drain to the master bath drain line. About two years ago I noticed noises and it would stop when I turned on that sink (the water muffled the sounds coming from the open AHU drain). I installed a vent on the AHU drain line to minimize the pressurization of the line and I cleaned the line. The sounds went away for over a year. When the flex hose section starts to clog (located in the vanity in the master bath) it will start to pop occasionally, so I just pull out the hose and clean it.
 
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IRS:
"What's initiating the noise? Have you tried changing the speed of closure of the valve?"
Is that the valve that 'fills' the toilet tank?

RB1957:
It's just started in the last few days.

DVWE:
I haven't been able to locate an expansion tank.

Thanks... Dik
 
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Is it just that one toilet? Is that valve old? Possibly, it's a problem with the toilet valve itself; they tend to make funny noises when they aren't working correctly.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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IRS: It's a distinct 'hum' from waterhammer and if I turn on the downstairs bathroom sink tap, it stops. I will replace the upstairs valve and see if that has any effect... it's time to replace it anyway.

Dik
 
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if it just started then something's changed with the system recently. maybe a valve is getting old and needs to be replaced (thank goodness we're not valves !) maybe someone knocked the fill valve (outside the tank, near floor level) partially closing (or opening it) and that's created the change in the system ?

another day in paradise, or is paradise one day closer ?
 
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waterhammer does not create a humming noise. it is more of a knocking or "hammering" noise as indicated by the descriptive name. what you describe sounds more like a valve that is not quite closed such as a fill valve in a toilet. that can create humming, vibrating, whistling and all sorts of noises.
 
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cvg: It's sort of a loud vibration sound... and it's tied into the water system... when the upstairs toilet flushes, there is a loud vibration sound and if I turn on the downstairs bathroom sink tap, it stops... maybe not waterhammer, but, something. I thought this was waterhammer.

Dik
 
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Check your water pressure. For years I had no problems then all of a sudden I had water hammer (which is a bang when you turn a valve off, not a hum). Turned out the water utility had jacked up the pressure in my neighborhood. I had to put in a pressure reducing valve (why don't they call these pressure regulators?).

You toilet valve may be chattering, dropping the pressure by opening the downstairs sink lets it shut fully. The toilet valve may need to be replaced but the root problem may still be excessive water pressure.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
 
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Waterhammer is a singular event, more like a single "thump" as the momentum of flowing water is absorbed by the plumbing upon the closure of a valve. Since the speed of sound in water is something like 3000 ft/s, water hammer lasts probably less than half of a second.

As a point of fact, a toilet flush typically cannot create a water hammer; the shutoff of flow into the tank is gradually reduced by the float valve, depending on type of float valve. The older ones with the floating ball and arm had a slightly quicker shutoff than the column float types.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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If one of our outside faucets is closed incompletely, or left on, and a hose with a small leak is attached, running one of the interior faucets would make the outside faucet buzz loudly.
 
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Might be that the valve is 'fluttering' giving rise to a loud 'whine'. Might not be waterhammer... it's not like a 'thud' when something is turned off... and it might be that the sound is transmitted through the house.

Dik
 
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If you have a pressure regulator in your plumbing (normally near the main water inlet) you may have to replace it. After 5 years in my new home, I had to replace mine due to water hammer from the outside sprinkler system.
 
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First replace the toilet float valve. These valves are very cheap and are not made to last long. The humming sound is one of the failure modes.
 
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Agree with all here - this is not water hammer, but a filling valve failure or hardening of a valve seat.

Just change the washer or diaphragm seal on the toilet in question and it will go away.

Been there, done that. It works.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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Thanks LI... I was going to replace the valve on the weekend to see if that changes things...

Dik
 
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