Where to Place Water Hammer Arrester

[rockncountry101]

I have a brand new manufactured home. In both bathrooms I have water hammer. Anytime the toilets finish filling up or I turn off the cold or hot faucets I hear a single BANG in the wall in front of the showers. This is in both bathrooms. I have tried to install a regulator and set the PSI to 75 to keep it under the 80 that the manufacturer recommends. I had a plumber tell me to install an arrester on both the hot and cold water inlets to the washer. I don't have a washer yet but this problem is driving me nuts. The manufacturer wants to send out a tech to cut into the wall but I don't want him destroying my drywall chasing what we many not be able to find. It could be a loose strap but I can't believe it would be in BOTH bathrooms. Would an arrester help and if so where do I install it? Thanks!

 

[LLigetfa]

Generally the hammer stops should be located close to any fast closing valve. You might get away with just one if it is placed further out than the other valves. The plumber that suggested placing one at the washer inlet may have assumed the fast closing solenoid valves of a wash machine was the cause or simply because they are the easiest location to install. Obviously, if you don't have a washing machine, then that is not going to work.

 

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[Jadnashua]

Most valves do not close fast enough to create a hammer. Things like washing machines, dish washers, some toilet valves, ice makers generally can close fast enough. The hammer is a result of inertia...the faster and larger volume of water there is, the more inertia...shut the water off fast, and it tries to keep going. This can cause the pipe to move, potentially slamming into a rigid object. Lowering the pressure drops the inertia, so the pipe can't move as far, and thus, maybe stop or lessen the intensity of the hammer. But, loose or poorly routed pipes can be a big part of the problem. A well located arrestor can make a difference, but may not fix it entirely if the pipe can move excessively. So, if you can isolate where the pipe is hitting, clamping it so it won't hit something should solve the problem.

 

[Terry]

Water hammer arrestors are normally placed at washers, dishwashers and icemakers.
They can also be installed for any fixture in the home. A good place to install in the bathroom would be the lav.

This one fits between the 3/8" outlet on a shutoff and the supply line to the faucet.

 

[rockncountry101]

Terry, would installing one on the hot and cold prevent the issue? It's clearly water hammer. I also noticed that the arresters are rated for up to 250 PSIG but on the installation instructions it notes that systems which exceed 60 PSI static pressure shall be installed with a pressure reducing valve upstream of the arrester. I have a regulator installed between the outside source and the inlet going into the water heater. I have it set to 75 PSI.

 

[Terry]

Installing on the hot and on the cold should help.
Also, setting your PRV down to 60 would help.

 

[Jadnashua]

As I said earlier...the higher the pressure, the faster the water can flow meaning that when you shut a valve, there's more energy to disperse. The amount of energy is related to the weight of the water * velocity squared...so a little bit faster makes a much bigger difference than just the weight of the water.

 

[rockncountry101]

What I meant to ask was would installing the two (one for hot and one for cold) on the inlet for the washer help overall? If I turn my pressure down to 60 it's just not enough pressure and still doesn't eliminate the problem. The builder of the home wants to come and start tearing drywall because he says more straps are needed. Thanks for your help!

 

[LLigetfa]

What I meant to ask was would installing the two (one for hot and one for cold) on the inlet for the washer help overall?

First off, if there is no washer installed, then the valves at the washer box would be closed. The hammer stops made to go inline on the supply hoses only work if the valves are open. If you open the valves with no washer supply hoses terminated on a wash machine, you will flood the laundry room.

You would need to cap the ends so that the valves can be left open.

How well the hammer stops might work depends on how far down the line the washer box is relative to the other fixtures that are generating water hammer. The hammer stops need to be at or near the end of the line terminating at the valve that creates the water hammer. Terry posted a pic of a hammer stop that can be mounted inline after the angle stop near the fixture that is generating the water hammer.

 

[rockncountry101]

The house is 60 feet long. The washer taps are almost right in the middle. I can hear the water hammer behind both shower stalls which are on opposite ends. I can also hear it in the utility room right around where the water heater and washer taps are. It's really strange but I'm not too keen on having them come and tear into walls and insulation.

 

[Terry]

The builder of the home wants to come and start tearing drywall because he says more straps are needed. Thanks for your help!

I wonder if foaming the wall would do it. I would first install the arrestors on the lav in that bathroom.

SPECIFICATION Sioux Chief 660-GTR piston-type water hammer arresters shall be installed where required on supply valves. Water hammer arresters shall be specifically sized and have sufficient volume of air to dissipate the calculated kinetic energy generated by closing residential or commercial faucets or valves. Arresters shall be installed on both hot and cold lines on the supply stops where applicable. Arresters shall be approved for installation with no access panel required.

 

[Reach4]

Anytime the toilets finish filling up or I turn off the cold or hot faucets I hear a single BANG in the wall in front of the showers.

A water hammer arrestor for a toilet should be at the toilet. Switching to a slower-close fill valve could help that. Consider the Korky QuietFill.

If you get water hammer from hot and cold faucets, close them slower. Or maybe you are closing them extra-fast as a troubleshooting technique.

The manufacturer wants to send out a tech to cut into the wall but I don't want him destroying my drywall chasing what we many not be able to find.

If the manufacturer wants to send out a tech on his dime, he probably know something.

 

[Jadnashua]

Without the pipes being properly supported, a hammer arrester won't be able to do its job.