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

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.
 
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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
 
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.
 
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?
 
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


Feck me, first flush of the chain this morning and it’s back! Turned off my internal stopcock, flushed both toilets, no fecking difference. Only difference is a change in pitch when I turn my stopcock off and on. Surely it can’t be anything do do with something in my house could it?


Any suggestions before I get back onto the water board?
 
Feck me, first flush of the chain this morning and it’s back! Turned off my internal stopcock, flushed both toilets, no fecking difference. Only difference is a change in pitch when I turn my stopcock off and on. Surely it can’t be anything do do with something in my house could it?


Any suggestions before I get back onto the water board?
I would change the stop cock
 
I would change the stop cock
As you were, the noise is there with the iso fully open, swapping it out wouldn’t make a difference. So maybe introduce a prv on the house side of the street stop cock
 
As you were, the noise is there with the iso fully open, swapping it out wouldn’t make a difference. So maybe introduce a prv on the house side of the street stop cock
That will be a bit of a job as the only bit of pipe I can get to between both stopcocks is this bent section coming up through the floor at the back of a cabinet and even that will be a mission without removing the dishwasher and housing. Everywhere else is out of bounds as the floors are boarded and have LVT on them. Could it be fitted after (or instead of) the house stopcock?

IMG_4326.jpeg


What I plan to do first though is replace both wc fill valves and maybe fit one of those shock arrestors.

It’s all been fine again since turning the water on and off. Does water pressure in the mains build up overnight?
 
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I would replace the stopcock with a lever valve.
A shock arrestor is a definitely a good idea as you have a water meter and these can cause problems.
You can get a mini shock arrestor that you tee into a 15mm pipe
 

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