Pipes bang when turning taps off.

[daverey]

Hi
Not sure if anyone can help me on this one.
We recently had our bathroom re-fitted, and ever since it was done there has been a banging noise in the pipes somehwere in the house whenever a tap has been turned off.
There is no noise at all when using the taps, but as soon as the flow is stopped there is a kind of double-knocking sound somewhere in the pipes. This happens when any tap in the house is used, and even after the toilet has re-filled, or when the dishwasher is on - basically whenever there has been some water flow in the house.
It also doesn't matter where the water is flowing, the noise always appears to come from the same place.
I tried locating the sound and placing wedges around the pipes, but to no avail.
The guy who fitted the bathroom has no idea what it is - does anyone know what this might be and how we could fix it easily?

Thanks in advance
Dave

 

[daverey]

apologies for answering my own question....
I have just been searching on the internet and culd the problem I describe be "water-hammer"???
If so it seems a good solution is to turn the main stop cock down a touch - I'll try this tonight.
Dave

 

[Bahco]

Could be the ball valve in your loft cistern needs attention.

 

[daverey]

Hi
Thanks for the reply - although we have a combi-boiler and don't have a loft cistern.

Dave

 

[petetheleak]

The guy cant be a plumber son if he doesnt know what is causing it.Would get the rest of his work checked out if i were you.

 

[daverey]

This is true - although to be fair, he was cheap as chips and actually did a cracking job of the rest of it!

 

[bengasman]

No real surprise; I know cheap plumbers and good plumbers but no good cheap plumbers.
Definitely water hammer. Remedy is simple and cheap. Clip hot and cold water pipes where-ever they are not supported for more than 2 meters. Especially in basement or in crawl space where the pipe comes from stop cock. As someone else mentioned; if your so called plumber had no idea, get the rest checked. It is one of the most basic things in plumbing. Very easy to find as well. When you find a length of unsupported pipe, have someone turn a tap on and off. You can see the pipe move when the tap closes. I remember one case where I saw the pipe move nearly 10 centimeters. Or about 4 inches in old money.

 

[daverey]

Just tried turing the stop-cock a little to reduce the pressure slightly, and hey-presto, no banging. I can't believeit was so simple (and I can't believe our "plumber" didn't know about it - but anyway...).
Thanks for all your suggestions though.
Dave

 

[abcdefg]

cnt belive your so called plumber couldent tell u that any plumber that has half a clue would know that was water hammer and the first and most simple remidy to try was to turn presure down a bit