Next door's foghorn

[Rod Hewitt]

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?

[BigWallop]

We had a neighbour a few years back with the same problem as this, and the plumber found out it was the rubber washer in the main stopcock had fallen off the head gear. It was vibrating like a reed on a clarinet, right through all the pipework in the area. The houses we lived in were all timber construction and the vibrations used to shake the whole house. It even caused ripples across the top of the pool.

[IMM]

You say when they are not drawing water? The cold tank may be filling and they are not aware of this. Tell them to fit a "full bore" mains stop c*ck. It could be the ball valve in the tank. Best have both replaced, it should not happen again.

[Tim Mitchell]

In article , Rod Hewitt writes

This happens in our industrial unit at work. It happens (only sometimes) when the hot water header tank is filling. It appears to be caused by a long length of unsupported pipework resonating.

I think changing the ballcock valve in the hot water header tank to a torbeck type thing (or maybe just a new ballcock valve) would fix it.

[IMM]

And install a shock arrestor.

[MBQ]

I had something similar after fitting one of those taps that cuts it's own hole. The valve in the cold water tank started shrieking when the tank was filling. Upon dismantling I found a little circle of copper.

MBQ

[Rod Hewitt]

"IMM" wrote in news:caov7l$o06$ [e-mail]:

You say when they are not drawing water?

No - I wrote this: "It does not seem to occur every time that they draw any water - but only from time to time."

I do not follow their habits sufficiently intently to know precisely what they are doing when it shrieks - but on the basis that many hours go by without it occurring, it seems safe to assume that they can draw some water, sometimes, without causing the problem.

[Rod Hewitt]

"IMM" wrote in news:cap74b$jua$ [e-mail]:

Maybe the landlord would do this, but I doubt it.

Many thanks for all the responses. At least it doesn't appear to be a danger.

[IMM]

news:cap74b$jua$ [e-mail]:

A shock arrestor is only around £10. It is in his interest to install a full bore ball valve as the problem will not then re-occur.

[N. Thornton]

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

[Bob Mannix]

It's possibly the toilet filling. One of ours does the same from time to time. The contributing factors are: the age and stiffness of the ball-valve diphragm (worse when its older and stiffer - as the actress said to the bishop), the presssure of the water (higher=worse) and the temperature of the water (colder=worse as the diaphragm gets stiffer) plus, of course, the resonant capability of the pipework. I changed the ball valve diaphragm once and it went away for a few months but comes back now when the conditions are right. It's only occasional now but I would probably add another pipe bracket somewhere with a rubber sleeve next to change the resonant frequency of the pipes next if I could be *rsed.

You can generally stop it by opening a mains tap as this drops the pressure a bit - in fact you can tap out signals by turning it on and off if you've nothing better to do - try it with next door's!

[IMM]

Just fit a shock arrestor next to the ball valve and stop messing about.

[Bob Mannix]

Firstly, I'm not messing about (well, other than by posting a reply) - if you read the text above you'll see I'm not doing anything, the severity of the problem not warranting it!

Secondly, the shock arresters are for water hammer, which generally occurs on tank/ball valve arrangements where the resonance occurs when the ball float moves up and down due to water ingress which moves the valve causing a spurt of water which causes the float to move etc., etc. or where pipes feeding mains taps are loose. It is not clear to me that the shock arrester would be effective for higher frequency resonances set up in diaphragms/washers, whic arren't really "hammer". Using an electrical analogy, the shock arrester adds a capacitive-resistive element to the circuit. It's size and shape will determine the range of frequencies it filters out.

Thirdly, they are reasonably sized devices and the area under the toilet cistern inquestion is somewhat cramped so I probably couldn't get one in if I wanted (at least, not neatly).

[IMM]

I have never come across a situation with any noise from pipework where they never cured it.

It is best nearest to the offending valve, but they will fully work, in the vast majority of cases, in any part of the offending pipework. Well in a domestic house that is. In most cases any shock is taken up by the water mains itself.

[N. Thornton]

IMM's solution to a dodgy rubber washer. Well, why not eh.

Regards, NT