I redirected my washer downstairs (directly below where it used to be) and since then have some pretty serious water hammer whenever the washer's cold water turns off. There is approximately 5 feet of 1/2" copper pipe that runs up to the ceiling. I installed a water hammer arrester (the $10 mini one from home depot) up toward the top of the 5' length of pipe. I also turned down the whole house's water pressure. I don't know the exact pressure but the cold water barely trickles out of the washer as a result (the rest of the house is fine). I also tried shutting the cold water valve to the washer half way closed but none of these have alleviated the problem. My wife also says that our shower's hot water bangs when you close it but I'm not convinced. Anyway, I NEED HELP! I thought of replacing the 5' length of pipe with 3/4" or putting a couple of elbows in the line (all in an attempt to slow down the flow so it does not bang) or put in a long 3/4" chamber or SOMETHING to stop the hammer OR just install a chamber. I'm not that confident that a chamber will work given that the arrester doesn't. If a chamber is the suggestion, should I make it 1/2" or 3/4" and how long should I make it (I've heard 12" is ideal but I do have room to be longer if necessary). Any help would be GREATLY appreciated!!

First and foremost, secure the pipes with real plumbing clamps. The kind with the threaded rod, base and clamp.

Second, make sure the arrestor is installed in the correct orientation.

Third, measure the water pressure at the washer and we'll work from here.

First and foremost, secure the pipes with real plumbing clamps. The kind with the threaded rod, base and clamp.

The pipes are not in contact with any studs (this is not a problem with banging pipes, it is water hammer).

Second, make sure the arrestor is installed in the correct orientation.

It is my understanding that arresters should be installed as close to the valve where there is an issue as possible. Unfortunately, the closest i can get is about 5' away (at the top of the vertical pipe that is hammering).

Third, measure the water pressure at the washer and we'll work from here.

I don't know the exact pressure but when i turn on my washer, the water is in no way forcing out into the washer basin the way it used to before i turned down the whole house's pressure. The washer's water pressure is quite low and takes quite a while to fill the basin.

Hammer and secured pipes are related. If the pipes can't move, it will have a hard time making any noise.

5' isn't a problem. Orientation is also defined as additude. If you were making an arrester with an air column, the column must be vertticle. It won't work sideways or upside down. That's what I mean my orintation.

No, turning down the flow has nothing to do with the pressure, but it should lessen the hammer.

Take a simple pressure guge with a hose fitting is all you would nned to check the pressure. You could probably even use a tire gage and fitting.

Sow closing valves are a possibility and so a re check valves on the water supply, but I didn't want to suggest these solutions quite yet.

Just so you don't think I'm making things up:

OMEGA-FLO™ 2-way Anti-water Hammer Solenoid Valves 1/2 " to 2 1/2 " NPT

Yes, EXPENSIVE.

The controls might be equally as difficult as well, but it would depend on the washer.
Say there was only one cold water supply valve and it operated on 120 V and you could not separate them. The washer valves may be rated for intermittant operation and you may not want them on most of the time.

The solution would be take the control signal and apply it to this valve and a delay on break timer. The delay on break timer would turn off the normal washer valve a little later than the anti-hammer valve. If this method were used, you would have to experiment with the timing because the washer sometimes introduces a small spray during the rinse cycle. I'm sure the time would be short. And you might have to extend the control signal to deal with the intermittand spray during the rinse cycle. It's not easy, but it is solveable.

Opening Time: 200 to 500 ms
Closing Time: 100 to 4000 ms

Another solution, if the washer valve would allow it, is to power the cold washer valve all the time and move the cold electrical connections to the anti-hammer valve. This would still likely require one delay on break timer.

Simple solutions first. These are too expensive.

KISS

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Originally Posted by Keithly

I redirected my washer downstairs (directly below where it used to be) and since then have some pretty serious water hammer whenever the washer's cold water turns off. There is approximately 5 feet of 1/2" copper pipe that runs up to the ceiling. I installed a water hammer arrester (the $10 mini one from home depot) up toward the top of the 5' length of pipe. I also turned down the whole house's water pressure. I don't know the exact pressure but the cold water barely trickles out of the washer as a result (the rest of the house is fine). I also tried shutting the cold water valve to the washer half way closed but none of these have alleviated the problem. My wife also says that our shower's hot water bangs when you close it but I'm not convinced. Anyway, I NEED HELP! I thought of replacing the 5' length of pipe with 3/4" or putting a couple of elbows in the line (all in an attempt to slow down the flow so it does not bang) or put in a long 3/4" chamber or SOMETHING to stop the hammer OR just install a chamber. I'm not that confident that a chamber will work given that the arrester doesn't. If a chamber is the suggestion, should I make it 1/2" or 3/4" and how long should I make it (I've heard 12" is ideal but I do have room to be longer if necessary). Any help would be GREATLY appreciated!!!!!!

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You need a Sioux Chief 660-H, which will thread directly on between the sill cock and the supply hose.

You also need to check and probably clean the screen at the solenoid where the supply hose connects to the back of the W/M.