Pipe hammering

How do I stop a shower hot water line from hammering when it is turned on other than opening it fast? Thanks

 

Usually hammering occurs when water is turned off. Water hammer arrestsers seem to work pretty good.

 

Water hammer usually occurs when you (or a solenoid like in a washer) turns off the water fast. All that momentum of water in the pipe stops suddenly, and you get a thump and the pipes bounce.

In your post, you make it sound like if you turn the water on slowly, you get the noise, but if you turn it on fast, you don't. This is more of a vibrating problem, usually due to a loose or worn rubber washer somewhere. It could be in the shower valve, or a nearby shutoff valve.

Can you confirm what exactly you're experiencing?

 

Yes, that is exactly what is going on. The valve is new. Would you recommend taking it apart and checking the washer?

 

If there is a vacuum breaker in the hot water line (perhaps at the hot water tank), it could cause a vibrating/hammering noise on a slow start.

 

Thanks for the reply. There aren't any vacuum breakers or anti-hammer restrictors in the systems.

 

Sorry for the delay in getting back Sydney. Finding the source of the vibrations is often difficult. First check would be a pressure reducing valve (PRV) near the water entrance, or the main shutoff valve. If it's only that one fixture that's vibrating, check any valves on that specific pipe run. If you can change or temporarily stop the vibrations by opening or slightly closing a valve, you've probably found the offender.

Could also be the shower valve itself too.

Unfortunately, I don't know a good way to find the offending valve/washer without tweaking each one to see if it changes.

 

Thanks, everyone for the replies and suggestions.

 

Zorfdt, You were exactly right about the washer issue. Even though it was a new valve I pulled it apart and the washer, in my opinion, looked like crap, must be an imported valve, so I replaced it. I haven't had any more noise from it since. I tried to replace the cold water one also since I had to buy a two pack but could not get the screw loose. So far so good. Thanks again.

 

Glad you got it tracked down and fixed! Hope to see you around here again soon!