High pitched sound that rises and falls for hours on end.

[morty1]

Hi Everyone,
For the life of me I can't find the cause of this problem. Go to bed and usually within 30-60mins it starts off with a whine that rises and falls and gets louder and louder and lasts till early morning/midday. Now the sound upstairs I think it's resonating up by the cavity around the chimney space. If I go into the loft directly opposite where the sound is eminating you can't hear a thing. Go back into the room and you can clearly hear it in the corner next to the chimney. When it's bad you can hear it also from the cupboard the cylinder is in which is downstairs. I've had the heating off for days makes no difference, turned the water off makes no difference. Ran the bath, shower and sink taps to see if any air is released and bled the life out of the radiators.It does appear though that through the day from the water being used, whether it's for washing machines, showers, sinks etc. the sound generally is not there. BUT come bedtime it's like clock work. Last night no sound at 2300 flush the toilet and low and behold the sound starts but we've even tried not using the taps or flushing the toilets at night and the bloody thing still happens.
Cylinder is a sealed system. We put an extension upstairs last year and it happend then but disappeared only to come back a few months later. Just a last ditch attempt for some suggestions before I get someone in.
Thanks in advance.

 

[johnny2007]

Someone practicing a single note on a flute next door?

 

[aveatry]

Are you on a water meter so you can check for a possible water leak. That would explain why you don't hear it when water is being used and so reducing the pressure so the leak is not happening until nothing is being used and there is pressure in the water supply

 

[denso13]

turned the water off makes no difference

Do you mean the main stopcock? Could be coming from a neighbour's pipework.

Mains pressure tends to be higher at night.

 

[CountryFan]

Any issues with system pressure loss on the heating circuit?

 

[morty1]

Do you mean the main stopcock? Could be coming from a neighbour's pipework.

Mains pressure tends to be higher at night.

I live in the countryside. Nearest neighbour is 250m away and each of us is connected to the main via a separate regulator

 

[morty1]

Any issues with system pressure loss on the heating circuit?

No pressure loss. It's an oil fired boiler which is in the garage. Honestly with the heating is on you don't even hear a gurgle in any of the rads. The heating system is still open vented.

 

[morty1]

Someone practicing a single note on a flute next door?

There is no one next door unless the pheasants have started a band

 

[morty1]

Are you on a water meter so you can check for a possible water leak. That would explain why you don't hear it when water is being used and so reducing the pressure so the leak is not happening until nothing is being used and there is pressure in the water supply

No water meter. There's about 250m of plastic from the regulator to our house. No change in water pressure. If we do get a leak even a small one we notice it straight away via the tap pressure

 

[morty1]

Do you mean the main stopcock? Could be coming from a neighbour's pipework.

Mains pressure tends to be higher at night.

We're in the countryside and there's a really long run of pipe and there's a regulator right off the mains

 

[denso13]

We're in the countryside and there's a really long run of pipe and there's a regulator right off the mains

And are you testing with the main stopcock turned off?

 

[mattylad]

Turn the stopcock off just before you go to bed tonight.
(fill a bucket with water for the loo first).

 

[morty1]

And are you testing with the main stopcock turned off?

Yes, turned it off while the sound was happening made no difference unfortunately

 

[Alec_t]

The heating system is still open vented.

Tie up the ball valve on the F&E tank in the loft temporarily, in case the valve is passing slightly and generating a vibration. Are there any drips from the overflow of that tank?

 

[CountryFan]

No pressure loss. It's an oil fired boiler which is in the garage. Honestly with the heating is on you don't even hear a gurgle in any of the rads. The heating system is still open vented.

Sorry, I got mixed up with what you wrote:

Cylinder is a sealed system.