Help/advice needed - noisy mains even with all taps turned off.

[Mottie]

I was transferred to someone else who put me on hold and eventually came back saying they have authorised for the street/boundary box/stopcock to be replaced - today! I told them that in that case I’ll hold up with my complaint unless that doesn’t happen. I’m only 50/50 as to whether they will actually replace the street box today. We'll see.

Well, a woman turned up to do it, said she’s just come to change the meter! I said they told me the whole thing needed changing and she said she ain’t doing that. Proper attitude on her. Showed her the noise as I know by now how to start it off and she said it was water hammer and was to do with my house plumbing or could have been two pipes rubbing together! I wasn’t having that but she was adamant. She replaced a non return valve (but said it was nothing to do with that), fitted a new (and different) type of meter, a smart one she said. Turned the water back on, noise was gone. I couldn’t reproduce the noise. When I asked her what had happened to the water hammer now, all she could say was that she reckoned it will come back.

Correct me if I’m wrong but water hammer is a bang or a bonk when you turn a tap off quickly or a ball valve in the toilet bobs up and down for a bit, it’s not a high pitched buzzing and screaming that will go on for literally hours when no water is going through the pipes, is it?

The fact that I got the noise with no meter sort of rules it out in my mind and I suspect it could have been the non return valve, could it?

She asked if I had turned it off at the inside stop cock and when I said I hadn’t because it was difficult to get to my new stop cock as I’d built my kitchen around it and it would mean a little bit of dismantling, she said "that was silly" and she had a smug look on her face. Of course, Mrs Mottie was all ”Oh dear, has she only got one arm then"? "No, two". "So, the same number of arms as a man then?" She was laughing her head off because a woman had fixed the problem and she got the 'ump when the woman was sitting in her van filling the paperwork in and I commented that she was probably just touching her nail varnish up and putting some fresh lippy on…

Anyway, fixed for now and hopefully that’s the end of it.

 

[blup]

The screaming sound might be related to the house stop cock not being fully open, especially if you’ve got no loft tank and the cold water for various appliances is on call direct from the mains

 

[blup]

Or a vacuum in the supply pipe

 

[Mottie]

The screaming sound might be related to the house stop cock not being fully open, especially if you’ve got no loft tank and the cold water for various appliances is on call direct from the mains

When I renovated the kitchen, I replaced the standard tap type stopcock with a 90° full bore valve. It’s definitely fully open.

Or a vacuum in the supply pipe

There is one supply pipe coming from the main which splits into two stopcocks, one to my house and one to the neighbour. They have no such noises.

It’s still okay at the moment with the new non-return valve and meter. Fingers crossed.

 

[dilalio]

FFS!
It was the suppliers meter end of.
And then they send a femgineer who's sole purpose is to prove she's got bigger Bollöx than a man.
Equality my arse!

 

[Mottie]

It was the suppliers meter end of.

Femgineer lol. Couldn’t have been the actual meter - there has been no meter fitted since Saturday but still had the noise. Could it have been the non return valve or does the new meter have some kind of shock absorbing ability?

 

[blup]

Or pressure relief

 

[dilalio]

Couldn’t have been the actual meter

When I say meter... I mean "their kit"!
With that mains burst photo you posted, all sorts of debris would have got shoved downstream and likely fouled up loads of filters/NRVs at the meters.