Water hammer trouble

[Komodo]

Thank you for making this forum available for non plumbers as well as professionals. As you probably guess, I'm not a professional plumber and need some advice. On the third floor of my duplex, I have what I think is called a Water Hammer. The symptom is that each time I open and close the hot water tap I hear a loud bang. It's only on the hot water tap in the bathroom sink. I tried to drain the water from the system but the banging came back in a few days. After doing some research on the net, I think I need to install a Water Hammer Arrester. I was hopping that someone with experience can help me determine if this is the proper next step and if so where do I put the Water Hammer Arrester. I included a crude map of my setup. I hope its OK.

 

[phishfood]

A hammer arrestor would most likely solve your problem. To avoid having to cut out walls, you could install the arrestor on the supply piping underneath the bathroom sink.

 

[majakdragon]

I would install it on the outlet pipe (hot line) of the water heater.

 

[Mr_David]

Although many think a water hammer arrestor is the fix-all for water hammer, it is not. The very few that I have installed in most cases did not solve the problem. You say it only happens when you use a particular faucet.
Sometimes it is just the old washer in the angle stop supply to the faucet. Try replacing the angle stops if they are the old style screw in type and not the 1/4 turn type. Is this hammer a new problem or has it always done that.
single handle faucet can also have loose or worn washers.

 

[LiQuId]

Back in the day One would make a air chamber from a pipe one size larger and install on the ends ofthe branch run.. these would eventually become water logged and fail to work, hence they are now not allowed by code.

As some have suggested, you could place a mechanical arrestor on the line and It may solve or diminish the problem, You could also Check the pressure available at the end line as If it is really high you will getr hammer also as the valve stops and the chatter runs through the pipe. in some cases a PRV valve will help, but the easier solution is to install a arrestor.

Also, Pex pipe installed dampens water hammer as it allows for deflection of the line.

 

[Caduceus]

I have to follow Mr David on this one. The problem probably is in the stem/cartridge or in the angle stop. Especially with the info that was given regarding the drain down and return of the issue.

 

[Komodo]

Thank you all for the fine advice. I started by replacing all the washers in the bathtub tap and then drained the pips. This worked for only three days. The banging came back. Then I installed a hammer arrestor on both the cold and hot water lines. It's been almost two weeks and all is well. Thank you again for helping me solves this problem.

 

[Caduceus]

Nice to hear that the issue has been resolved. One more thing you may want to check is the house pressure. For the washer replacement to work and then come back, then the arrestors to work may indicate that you have high pressure and may be causing some internal damage to your faucets. A gauge that screws onto your hose connection is available at home improvement stores and it couldn't hurt to check. Depending on your house piping, stories and fixtures your pressure should be between 45 and 65 psi. Anything over 75 is considered damaging.
Thanks for the update.