Odd whooshing noise

Hi, it's detached. I can't be 100% certain, but it does seem to have started after we had a new boiler installed 18 months or so ago, hence when I initially posted it, I assumed it was boiler related. Maybe the boiler letting off pressure, or pressurising, not sure as I'm not not a plumber so just guessing.
 
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Maybe the boiler letting off pressure, or pressurising, not sure as I'm not not a plumber so just guessing.

If it's a pressurised boiler system - you will see a drop in pressure on the gauge and eventually it will stop working due to low pressure.
 
It works fine and has done every since we have had it. Just this noise a few times each day, and as I say, I can't be 100% whether it is from the boiler unless I spent hours stood in the garage next to it to try to catch the noise.
 
It works fine and has done every since we have had it. Just this noise a few times each day, and as I say, I can't be 100% whether it is from the boiler unless I spent hours stood in the garage next to it to try to catch the noise.

Do you have a sound triggered recorder, or a Smart Phone able to record when it hears a noise?
 
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Well after testing for a while I don't think it's that. We have three toilets, on each, I flushed and then marked a line at the water level when they had filled. A few hours later I checked the water levels, and the same. Then later when we heard the noise, I checked again and all still had the same levels. It definitely sounds like a brief rush of water, as I have also noticed that if I am in the lounge and my wife briefly uses the tap in the en-suite which is directly above, you get the same/similar sound. Because it might only happen two or three times each day, it's hard to be 100% where the noise is coming from although we do have the water tank in the roofspace, the en-suite, and the boiler in the garage all roughly below each other from top to bottom, and that seems to be the area of the house that it comes from.
Where did you check the water levels? If you checked the water levels in the toilet pan itself, then they will always be the same as excess water overflows over the trap at the back. If you checked the cistern i would also expect the levels to be the same after you've heard the noise as it's just refilled.

I'd put money on it being leaking flush valve with the cistern periodically refilling as what you've described is the classic symtom of a leaking flush valve. Put some paper on the back of the toilet pan above the water line when the toilet hasn't been used for a while. If it's leaking, the paper will get wet and that's your culprit. The alternative is to turn off the water to each cistern overnight. Turn the water back in in the morning and you'll hear the leaky one refill.
 
I checked it in the cistern, I flushed, waited until it stopped and then drew a line at the water level. I will give it a try, isolating the feed to the cistern - thanks.
 
Well after testing for a while I don't think it's that. We have three toilets, on each, I flushed and then marked a line at the water level when they had filled. A few hours later I checked the water levels, and the same. Then later when we heard the noise, I checked again and all still had the same levels. It definitely sounds like a brief rush of water, as I have also noticed that if I am in the lounge and my wife briefly uses the tap in the en-suite which is directly above, you get the same/similar sound. Because it might only happen two or three times each day, it's hard to be 100% where the noise is coming from although we do have the water tank in the roofspace, the en-suite, and the boiler in the garage all roughly below each other from top to bottom, and that seems to be the area of the house that it comes from.
It would be at the same level you numpty! It’s just filled itself back up again!
Come on man! Listen up! ;)
 
It would be at the same level you numpty! It’s just filled itself back up again!
Come on man! Listen up! ;)
But if it was filling up slowly after the initial fill, then it wouldn't be the same level it would be above the line I had marked after that initial fill, you numpty!
 
But if it was filling up slowly after the initial fill, then it wouldn't be the same level it would be above the line I had marked after that initial fill, you numpty!
It will never be above the line you marked. The level will slowly drop as the water leaks through the flush valve to the point the float valve opens (the whooshing sound you hear) to replenish the lost water. It won’t fill slowly, it will fill quickly, hence the noise.

There are a lot of very knowledgable and experienced people on here who offer that knowledge for free. Best to be respectful to gain that help, even if some are a bit more direct.
 
Apologies for the comment, it was just that everyone else has been really helpful, then you just get called a numpty.

Anyway, what I was saying is that once flushed, if I then mark the line and the water stays at the same level, then that suggests that water isn't leaking from the cistern, and that it isn't slowly filling up after being flushed. Unless there is a leak and it is being slowly replenished, but if that was the case, then why would you get the sudden noise as if it has just reached it's limit?

I have isolated the cistern in the en-suite and assume that if we don't get the noise all day, that it must be an issue with that cistern; so I will be a step forward.
 
Anyway, what I was saying is that once flushed, if I then mark the line and the water stays at the same level, then that suggests that water isn't leaking from the cistern, and that it isn't slowly filling up after being flushed. Unless there is a leak and it is being slowly replenished, but if that was the case, then why would you get the sudden noise as if it has just reached it's limit?

It will not slowly refill, cistern fill valves and the water exhibit some hysteresis. The water level will be refilled a little way above the shut off point, by the bouncing of the float valve due to ripples in the water surface. Only once the level drops some way, will the fill valve reopen. Chances of you spotting it - remote, though you may be able to reproduce the noise by having someone pushing the float down, as you listen ....

The best way to diagnose which might be making the noise, is to isolate then one at a time, by means of an isolator valve, or by tying up the floats.
 
Jaysus wept!
1 There is nothing wrong with the equilibrium fill valve.

2 The flush valve has a slow let by on its outlet seal.

3 The equilibrium valve is designed to have a delayed opening so an exact flush amount is delivered.

4 Look in the bog and see which one has a fine stream of water flowing into the pan!
Whichever it is, is the one causing the problem.

5 If you’re on a water meter get it sorted. It’ll cost a fortune! X
 
Jaysus wept!
1 There is nothing wrong with the equilibrium fill valve.

2 The flush valve has a slow let by on its outlet seal.

3 The equilibrium valve is designed to have a delayed opening so an exact flush amount is delivered.

4 Look in the bog and see which one has a fine stream of water flowing into the pan!
Whichever it is, is the one causing the problem.

5 If you’re on a water meter get it sorted. It’ll cost a fortune! X
Put a sock in it :)LOL:) get back to the CC you!
 

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