Rod Hewitt wrote in message ...
Well good ol' neighbours. They have a problem with their water supply.
Several times a day it makes an awful noise - trying to describe it I
came up with foghorn - but a bit higher pitched.

What is worrying us is that the vibrations are coming up through our
separate mains and making our pipework vibrate quite seriously. My feet
can feel it through our concrete floor several feet away from where our
main comes up. Despite the two pipes splitting several metres away and
being underground.

They have had it suggested to them (by someone) that their stopcock
needs replacing, but I can't quite get my head around what could be
wrong to make this amount of noise and vibration. It does not seem to
occur every time that they draw any water - but only from time to time.
Oddly, always sometime around 18:00 to 18:30 and going on for anything
from a minute to maybe quarter of an hour. The only mechanism that I can
think of that could make this noise is water being forced back through a
dodgy non-return valve.

We would like it sorted and reckon that our best way of achieving it is
to point out to their landlords that there is some danger (if there
really is). Otherwise we might have to live with it for several weeks
until arse is gotten into gear.

Any suggestions on what is really happening here?


Water systems can go into resonance, this is whats happening. It comes
down to chance to a fair extent: if the position of any movable bit in
the system (eg a rubber washer) just happens to be such that as the
pipe vibrates the flow changes, and this causes pressure waves that
happen to increase the vibration, then youre in for a foghorn.

Solutions:
1. replace rubber discs in whatever waterflow item is causing the
foghorn. If theyre not aware of drawing water at the time it'll be a
tank / cistern ballcock. Theres no reason to change whole ballcocks.

Often its also poss to stop it by turning a service valve down a bit
to reduce flow to the point where the horn stops. This is a 30 second
job.

As far as the neighbour goes, if the vibration forces from their pipes
cause your pipes to spring a leak and do £10,000 worth of damage,
theyre going to have some problems. Maybe.


Regards, NT