Water Hammer...

danza

danza

danza

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Is there a surefire way of preventing water hammer? Will an arrestor work? Every time a tap is shut off abruptly, the washing machine stops filling or the toiletfinishes filling, the pipes bang downstairs in my house.

I'm doing a kitchen install shortly, and would rather not have to pull up the new floor if a pipe bursts due to water hammer. Can I fit an arrestor just after the stop ****? Is there a good way of testing/regulating water pressure in case that's the problem?

Any thoughts?
 
You need a Mains Water Pressure Test Gauge, cost a tenner.

http://www.toolstation.com/shop/p75711

Have you always had water hammer, or has it just started, many causes, worn valves, unsecured pipes, etc.
If you have high pressure, you could think about a mains water pressure reducing valve, this will cure the water hammer noise.

EDIT: Mains pressure is usually 2 -4 bars (30psi-60psi ) depends on area though.
 
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We've been in the house for 6 years and it's done it since (I would guess) way before.

I'll measure the pressure and go from there.
 
Before buying the tester just turn your stopcock right down until the water is only flowing slowly out of the taps. Is the knock still there? If it is then you need to find where the pipes are knocking and clip them. If it doesn't knock keep increasing pressure until it does and quarter turn it back.
 
Pabl0 said:
Before buying the tester just turn your stopcock right down until the water is only flowing slowly out of the taps. Is the knock still there? If it is then you need to find where the pipes are knocking and clip them. If it doesn't knock keep increasing pressure until it does and quarter turn it back.
Click to expand...

Do this :)
 
Not mega scientific I know but if for instance you had a long run to a valve this is going to be the most likely place that the hammer is developing. You could introduce a link of 4 90deg bends with short lengths between. This will limit the momentum in the run and also reduce the flow rate, both of which should reduce the hammer. Soft shut valves and accumulators will also do the same in a more technical way.
 
Fit a pressure reducing valve to your incoming mains pipe at the stop tap.
Buy an adjustable one that has a good flow rate, you will then be able to fix the water hammer.

BTW: throttling down the stop tap will not change the pressure, but will change the flow rate, and you want a good flow, just with less oomph behind it :-)
 
Water hammer is a function of momentum and thus flow rate. Flow rate is related to flow resistance and pressure drop. The pressure load of a rapidly closing valve is generally only a fraction of the spike caused by the "instantaneous" decceleration of the fluid.
 
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