"Roger" wrote in message
...

"SmileyFace" wrote in message
...
There's a loud humming noise - a bit higher frequency than mains hum -
coming from the water main pipe (the one with the stop tap) and
reverberating through the house.

Sounds like water hammer to me, have you checked the ballcock valve in the
water tank in the attic?

Just because you haven't changed anything in your installation the water
board may have increased / decreased the pressure of the incomming water to
your property which can cause watter hammet o come and go without any reason
(that you are aware of anyway) and can be a bitch to catch..

What is youe incomming water pressure anyway?

A way arround the problem (if it is very high pressure) is to install a
pressure reducing valve on the incomming water mains and set it to something
lower that tne incomming water pressure (mine is set to 3 Bar and the
incomming water pressure changes from 2.5 Bar to more that 7 Bar)

By setting the pressure to something fixed you it gets much easier to find
the offending valve and get it fixed...


I get a noise like that too, but only when water is running.

Again sounds like either an airlock somewhere or water hammer..


My noise varies in tone with the rate of flow of water and is lowest when
the washing machine is on maximum flow, dropping to a low growel. I
believe my noise is caused by the turbine type flowmeter installed in the
water co stop cock hole in the street. The water meter is about 20 m of
underground run from the stop cock in the kitchen.

If the noise is created by the meter then it's probably a airlock in the
meter that causes cavitation (microscopic areas where the water boils due to
very low pressure, very bad for the impeller...) but then the noise will be
very much related to use, ie. more use, faster spinning impeller - more
cavitation...


Though your noise is unrelated to your water flow I wonder if could be due
to the noise of your neigbours water meter conducted along your pipe from
some combined water meter block feeding all the houses.

Have you tried to close the stopcock in front if the meter, that will tell
you if the problem is yours or comming from somwhere else, close the stop
cock and open a couple of taps in your house (tie up the ballcock in the
water tank in the attic if you have one). Is it still noisy, then it would
have to come from outside your dwelling and pretty mich out of your control
anymore.


It's all a bit unlikley, but then your noise must be coming from
somewhere.
Can't say I've ever heard comment on water flow noises generated by water
meters. Can they really do this?

In theory yes but they would have to 'spin faster' than the water they
meassure to create the microscopic areas with very low pressure and
subsequent boilg / explosion of the water, and since the impeller is driven
by the water the impeller would be spinning slower that the water if you
know whet I mean...




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