Plumbing Q: Annoying water hammer - PeachParts Mercedes-Benz Forum

spdrun · #1 02-01-2014, 09:58 PM

My shower always had a bit of water hammer at certain temp settings. I changed the leaky old tub spout, thus changing the length (and resonant frequency) of the system slightly. Feels like it made the water hammer (more of a buzz) at certain temp/pressure settings worse.

Putting a plastic gasket behind the tub spout reduced the problem, but didn't totally eliminate it. Any suggestions to get rid of the issue entirely? The vibration can't be good for the copper pipes in the wall!

Accessing the pipes would require cutting a hole in the kitchen wall (the wall on the shower side is tile over brick!) so hopefully that won't be needed.

kerry · #2 02-01-2014, 10:18 PM

Put a shock absorber in the system. They sell special anti-hammer shock absorbers. I've solved it in the past by T'ing into the line and putting a length of dead end pipe in the T and the air in that pipe absorbs the shock.

KarTek · #3 02-01-2014, 10:19 PM

I have heard this before in other systems but never had to fix/deal with it myself. I suspect it's the valve vibrating as water moves through it. If it was me, I'd try replacing the valve gaskets first and see if newer, softer rubber makes a difference.

True water hammer is a bang when a valve is closed suddenly and usually requires the addition of a small reservoir to trap air and act as a damper.

DeliveryValve · #4 02-01-2014, 10:52 PM

Quote:

Originally Posted by kerry

.... I've solved it in the past by T'ing into the line and putting a length of dead end pipe in the T and the air in that pipe absorbs the shock.

This^^. I've solved it every time by adding this extra pipe going upwards close to the valve.

.

cmac2012 · #5 02-02-2014, 01:52 AM

The shock absorber is much better IMO. Putting a length of pipe above the valve on a T works and is a classic fix. However, under that pressure, air will be absorbed by the water eventually. When the water reaches the top, you have to turn off house water and open an outdoor spigot - something lower than whatever is hammering again anyway. The water in the cavity will drain out and you have your shock absorber back. For awhile.

Also, the shock absorbers are easier to install after the fact - you can put them on the line in a crawl space, preferably semi-close to the hammering valve. Even under the sink is doable. There's a piston that compresses the air, so water can't run into the cavity. I still slope them upwards from the pipe, if it's horizontal, based on pure superstition. Putting an empty length of pipe above valves usually would require taking sheetrock or tile out.

Stretch · #6 02-02-2014, 02:00 AM

I'd also get a water shock absorber.

Here in Holland it is difficult to get old fashioned screw thread taps (in good quality) so most taps are of the lever on / off system - sudden shocks everywhere - consequently I five shock absorbers positioned at strategic points throughout the house. (Wasn't cheap but it works)

barry12345 · #7 02-02-2014, 12:36 PM

May be a temperature moderation valve noise rather than a water hammer. Water hammer is usually only there when you shut a valve I think.

May be easiest to disable the feature or adjust it out. I do not know if this is possible or not. May want to contact the fixture manufacturer. Chances are you would not be the only owner with this issue.

I have installed some Italian European plumbing accessories.

spdrun · #8 02-02-2014, 12:42 PM

I can try to replace the valve "cartridge" -- it's an American Standard valve. Sounds easy -- problem with this is that there's no water shutoff to the valve. I'd have to ask for the water to the building to be shut off and drained, and would prefer not to unless I really have to.

Stretch · #9 02-02-2014, 12:46 PM

You can get pipe freezing kits - freeze the pipe - cut - fit new stop cock

spdrun · #10 02-02-2014, 12:55 PM

Quote:

Originally Posted by Stretch

You can get pipe freezing kits - freeze the pipe - cut - fit new stop cock

Very little room to work -- the opening for the valve is maybe a 10-12 cm circle in a brick wall.

Stretch · #11 02-02-2014, 01:00 PM

And on the other side of the wall? (It's a long pipe!)

spdrun · #12 02-02-2014, 01:10 PM

Quote:

Originally Posted by Stretch

And on the other side of the wall? (It's a long pipe!)

There's a kitchen, which I would (in an ideal world) not knock holes in the wall of. Though if I do end up cutting some plaster, it may finally give me the impetus needed to tile that wall!

unkl300d · #13 02-02-2014, 02:49 PM

So, are the valve washers made of rubber or ceramic?

I have resolved hammering noise by replacing the rubber washers and re-tightening the washer retaining screw.

Sometimes they get loose and cause the banging noise.

The other options mentioned also work in case the water lines don't already have them.

Stretch · #14 02-02-2014, 02:56 PM

Quote:

Originally Posted by spdrun

There's a kitchen, which I would (in an ideal world) not knock holes in the wall of. Though if I do end up cutting some plaster, it may finally give me the impetus needed to tile that wall!

That sounds like one of my never ending automotive projects - don't go down that route!

cmac2012 · #15 02-02-2014, 03:20 PM

Quote:

Originally Posted by barry12345

May be a temperature moderation valve noise rather than a water hammer. Water hammer is usually only there when you shut a valve I think.

May be easiest to disable the feature or adjust it out. I do not know if this is possible or not. May want to contact the fixture manufacturer. Chances are you would not be the only owner with this issue.

I have installed some Italian European plumbing accessories.

Oops, didn't read the OP closely enough. The only time I experienced this was with a bathroom faucet. I eventually replaced the faucet and it stopped. If something is faulty, loose, or something with the gasket or the shaft, can make that happen. But that's not a really definitive solution.