Whenever a tap or cistern valve is turned off there is a short hammering noise. This occurs only on taps or valves connected directly to the mains and not those connected to the cold or hot water tanks. This problem started a few months after replacing a toilet inlet valve (connected directly to the mains) but I am not sure if this has caused/introduced the problem.
Any ideas before a leak occurs!!!

Gary Cash, March 2010

noise of water flow sounds like you have high pressure mains.
you quieten them down by slightly reducing any isolation valves under the tap but not to much or you'll so the flow.

hi-spec plumbing & heating (essex), March 2010

Hi
Thanks for the 2 inputs, much appreciated. Yes I turned the stop cock off to change toilet valve. I have also been adjusting the stop cock to quieten a noisy tap (noise of water flow). So, it looks like I need a warter hammer arrestor...do you agree?

Thanks

Gary

Gary Cash, March 2010

you won't get a leak from water hammer.
did you shut the stopcock to change the toilet valve ?
you can sometimes try shutting the stopcock slightly
but don't over do it or you'll start reducing the flow.
water hammer is pressure related and if that don't cure it fit a water hammer arrestor.

hi-spec plumbing & heating (essex), March 2010

try altering position of stop tap, if its been in one position for ages then switched off and on again but not to same position you can have problems. Also get water pressure tested. Often find this becomes evident when new valves fitted as new valves shut off more instant than old ones. Anything over 3 bar and you are likely to get problems

rawplumb, March 2010