I have read many posts about this problem and the answer is usually
"replace your ball valve washer". I have had a look in my toilet and
I do not exactly which part is the ball valve, although I do know
which part of the mechanism causes the water hammer. Also the parts
that causes the water hammer are made from plastic and do not have an
existing washer in the assembly.
I get water hammer through my pipes just as the cistern is at the end
of its refill. The long arm attached to the float has what looks like
a plastic screw mounted on it at the opposite end to the float. As
the float rises this screw pushes a "piston" into a "cylinder" (a
valve??) which eventually stops water flowing into the tank. If I
flush my toilet and push the piston with light pressure I can
reproduce the water hammer effect. The fact that the flowrate into
the tank slows as the piston is pushed in makes the water hammer noise
The piston and cylinder (valve?) are made from a white plastic. The
piston fits loosely but I cannot pull it out of the cylinder. Does
the washer go into the cylinder before the piston, preventing the
piston from vibrating as it is slowly closed? B&Q have a ball valve
diaphragm washer for
98pence(http://www.diy.com/bq/category/category.jhtml?CATID †735. Is
this what I need?
On 2 Dec 2003 07:59:48 -0800, firstname.lastname@example.org (anon) wrote:
You have identified the ball valve correctly.
Replacing the washer may help but generally the problem is due to
pressure/flow being too high.. You could try that first, and then
if not, fit some form of flow restrictor like a service valve in the
pipe. A more drastic solution is to replace the ball valve with a
Fluidmaster or Torbeck type. These come with a flow restrictor which
fits in the valve itself.
To email, substitute .nospam with .gl
A torbeck valve has the added advantage that it operates over a very small
change in level - maintaining full flow until *just* before it shuts off.
This would be a direct replacement for your existing ball valve, and very
easy to fit - but the bit inside the cistern is much smaller than a
conventional ball valve.
The trouble with a Fluidmaster is that it cuts off the water very suddenly.
This could make water hammer even worse.
Isn't one cause of water hammer due to un-clipped pipes?
I fitted a Fluidmaster with some difficulty. It is a bottom fill cistern and
the valve needed to be at the same end as the handle / siphon which limited
space. I also had difficulty adjusting the height of the water without the
valve body preventing the lid from fitting properly.
> > >I have read many posts about this problem and the answer is usually
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.
email@example.com (Zymurgy) wrote in message
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
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.
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
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