"BigWallop" wrote in message
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"anon" wrote in message
om...
(Zymurgy) wrote in message
. com...
(anon) wrote
I have read many posts about this problem and the answer
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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.

Have a look on the pipe feeding the cistern to see if there is a service
valve. It looks very like a straight plumbing connection, but it has a
small slot on a circular shaped piece in the middle.

This service valve will allow you turn down the water flow which reaches
the
cistern, and will also reduce some of the pressure being placed on the
float
valve inside.

Flush the loo and then put a screwdriver in the slot on the service valve.
When the hammering begins, turn the screwdriver slowly until it stops.

SORRY !!! I mean till the hammering stops, not the screwdriver.


Flush the loo again and make sure the water is still flowing fast enough
to
fill the cistern quickly, but not under to much pressure that it causes
the
hammering.