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(Zymurgy) wrote in message . com...
(anon) wrote
I have read many posts about this problem and the answer is usually
"replace your ball valve washer".

I get water hammer through my pipes just as the cistern is at the end
of its refill.
If I flush my toilet and push the piston with light pressure I can
reproduce the water hammer effect.

I'm no toilet expert, but I believe water hammer occurs when the flow
is abrupty stopped. e.g. when turning off a tap sharply, causing
standing waves back down the pipe.

Is the ball valve sticking, do the mechanisms move smoothly ?

Alternatively, new inlet valve assembly's are cheap enough, i'd change
it as in some cases it'd be easier than trying to diagnose what's
wrong inside your current one.

HTH

Cheers.

Paul.

Thanks for all the replies. Everything moves smoothly until the water
level is nearly full and the ball valve starts to close. The piston
part vibrates inside the cylinder part which is what causes the water
hammer. This loud humming noise goes on for about 20 seconds until
the valve finally closes. I expect that the vibrations of the valve
cause the flow to be started and stopped repeatedly at high frequency,
causing the hum.

There doesn't appear to be a washer inside the assembly, so maybe the
valve has become loose allowing it to vibrate. If I push the valve
with my finger, partially closing it I can cause the humming noise.