Hello

We've had a problem with banging mains water pipes recently which I traced
back to a cistern valve that I recently replaced. The valve is a very
compact bottom entry type with a float on a very short lever - I believe
they are called Torbeck valves.

http://www.toolstation.com/shop/Plum...ngs/d20/sd2835 - see
item with Code 32033

It seems like the valvle is on a hair-trigger and the slightest vibration
can set off a short cycle of open/close giving rise to quite a loud
water-hammer in the mains pipework. This can happen when a cold tap is
turned on or (more disconcertingly) when someone sits on the loo - I think
this causes a slight wave in the cistern water leading to a movement in the
float.

Any suggestions?
Is it a feature of this model of valve, a fault in this particular valve, or
does the problem lie with the pipework or mains pressure?

Thanks for any advice
Thomas

"Thomas" wrote in news:ZE2ss.471501$Bz2.264444
@fx11.am4:

http://www.toolstation.com/shop/Plum...ngs/d20/sd2835

Not much yo ucan do other than replace the washer - it may have lost its
resiliance and therefore some tolerance to slight fluctuations.
Alternatively consider changing to a Fluidmaster Valve.

On Nov 24, 11:59*am, "Thomas" wrote:
Hello

We've had a problem with banging mains water pipes recently which I traced
back to a cistern valve that I recently replaced. The valve is a very
compact bottom entry type with a float on a very short lever - I believe
they are called Torbeck valves.

http://www.toolstation.com/shop/Plum...gs/d20/sd2835- see
item with Code 32033

It seems like the valvle is on a hair-trigger and the slightest vibration
can set off a short cycle of open/close giving rise to quite a loud
water-hammer in the mains pipework. This can happen when a cold tap is
turned on or (more disconcertingly) when someone sits on the loo - I think
this causes a slight wave in the cistern water leading to a movement in the
float.

Any suggestions?
Is it a feature of this model of valve, a fault in this particular valve, or
does the problem lie with the pipework or mains pressure?

Thanks for any advice
Thomas

These valve are pilot operated. ie the float controls water with a
needle valve into a chamber with a diaphragm that actually does the
business.
The banging is caused by a wave/ripple on the surface of the tank
water that just happens to be the frequency that corresponds to the
valve opening and closing.

So it's because of the size of the tank and water flow.
Try throttling the water flow. The isolating valve will need to be
nearly closed to have any effect.
If that doesn't work, try floating a plastic ball inside the tank to
interfere with the wave pattern on the surface of the water. Make sure
it doesn't interfere with the float.

Try adjusting the float so there is less water in the tank.

Try fitting a condom or similar on the water valve outlet. (Reduces
splashing/wave effects.)

Obviously, cut the end off the condom!

"harry" wrote in message
...

Obviously, cut the end off the condom!

But that'll make the cistern pregnant won't it?

Thanks for the helpful suggestions.

I played around with the float level and reassembled.
So far so good :-)

Thanks again
Thomas

On 24/11/2012 11:59, Thomas wrote:
Hello

We've had a problem with banging mains water pipes recently which I traced
back to a cistern valve that I recently replaced. The valve is a very
compact bottom entry type with a float on a very short lever - I believe
they are called Torbeck valves.

Torbeks are supposed to reduce water hammer :-)


--
Dave - The Medway Handyman www.medwayhandyman.co.uk