Have a Ferolli Modena Combi Boiler - a year old. Water supply is direct from the mains. When heating first comes on all is quiet. After about half and hour there is a rushing sound that can be heard all over the house (sounds like a really bad draft coming under the door). Noise stops when hot water is turned on the starts again when CH comes back on. Any ideas?
Rushing Sound
- Thread starter LesP
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I'm not a plumber but I wonder if it could be 'kettling' which is the water boiling at the heat exchanger. When hot water is turned on the heat is transferred to heating the water - so the kettling stops.
I'm sure one of the plumbers will be along to shoot me down before long.
joe
I'm sure one of the plumbers will be along to shoot me down before long.
joe
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I have the same problem but it only seems to be in 2 rooms that are welll away from the boiler. the problem seems to have started ever since we got trv's fitted on all the boilers & an extra radiator fitted, before then we couldn't hear the central heating system work at all. We did get one bypass fitted rather than leaving 1 radiator without a trv.
Teh sound is like a cistern filling in the 2 rooms & can be loud enough to prevent sleeping at night, so any advice would be much appreciated
Teh sound is like a cistern filling in the 2 rooms & can be loud enough to prevent sleeping at night, so any advice would be much appreciated
What I meant was:-
When the system is on, the pump is running. If the thermostatic valves close down (because every room is up to temperature), then as they close down they can start to make a wooshing sound as the pressure builds up. it's a bit like putting your thumb over the end of the garden hose, it's easy to slow the flow a bit, but surprisingly hard to shut it right off. As you close it off, the pressure rises. High pressure equals noise.
You can establish if this is your problem by going to the radiator and opening the valve a bit (or closing it as no flow equals no noise). if the noise changes/ goes away, then that proves the case.
The remedy is to fit a bypass circuit (this is already built in to some boilers, particularly combis), which automatically opens when the condition occurs and allows the water an escape route round the system, but not through the radiators. If you have a bypass, it may need to be adjusted to get everything working properly. There are other ways to deal with this, such as variable speed pumps, but they aren't relevant to a combi installation, because it has it's own built in pump.
So Macbee needs to trying lowering the setting on the bypass valve as does LesP. If the setting is too low, the hot water may go round the bypass circuit only and rarely if ever get to the rads, so it's a bit of trial and error. Or look at the Danfoss site for their advice on setting their bypass valve. My bypass valve at home works fine set at the minimum possible pressure, but I have a variable speed pump. All I hear is the boiler, and that is very quiet.
When the system is on, the pump is running. If the thermostatic valves close down (because every room is up to temperature), then as they close down they can start to make a wooshing sound as the pressure builds up. it's a bit like putting your thumb over the end of the garden hose, it's easy to slow the flow a bit, but surprisingly hard to shut it right off. As you close it off, the pressure rises. High pressure equals noise.
You can establish if this is your problem by going to the radiator and opening the valve a bit (or closing it as no flow equals no noise). if the noise changes/ goes away, then that proves the case.
The remedy is to fit a bypass circuit (this is already built in to some boilers, particularly combis), which automatically opens when the condition occurs and allows the water an escape route round the system, but not through the radiators. If you have a bypass, it may need to be adjusted to get everything working properly. There are other ways to deal with this, such as variable speed pumps, but they aren't relevant to a combi installation, because it has it's own built in pump.
So Macbee needs to trying lowering the setting on the bypass valve as does LesP. If the setting is too low, the hot water may go round the bypass circuit only and rarely if ever get to the rads, so it's a bit of trial and error. Or look at the Danfoss site for their advice on setting their bypass valve. My bypass valve at home works fine set at the minimum possible pressure, but I have a variable speed pump. All I hear is the boiler, and that is very quiet.
Ricarbo,
Many thanks for your answer; I have checked as you said & indeed when you either open or close the trv the noise stops. I am a little unsure though how to adjust the bypass as by the looks of it is just bit of rubber pipe between 2 points under the floor, also i'm unsure if my combi boiler ( a Worcester Bosch 240) has a bypass circuit & the help desk at the company seemed unsure what i was meaning suggesting it may be a faulty trv; perhaps it was my explanation right enough. So any further tips as to how to adjust the bypass, they would be much appreciated?
Many thanks for your answer; I have checked as you said & indeed when you either open or close the trv the noise stops. I am a little unsure though how to adjust the bypass as by the looks of it is just bit of rubber pipe between 2 points under the floor, also i'm unsure if my combi boiler ( a Worcester Bosch 240) has a bypass circuit & the help desk at the company seemed unsure what i was meaning suggesting it may be a faulty trv; perhaps it was my explanation right enough. So any further tips as to how to adjust the bypass, they would be much appreciated?
macbee, if the bypass is (a) rubber and (b) under the floor, then you have a disaster waiting to happen. I have a hunch that your pipe under the floor is something else though - can you describe its colour and tell us what's connected at the ends of it?macbee said:
Regarding the TRV, and the whooshing, if the noise doesn't stop then you have a stuck or faulty TRV.
As an alternative to replacing or serviving it, at thus cold time of year, do you have a TRV on every single radiator? If so, is there just one radiator that you can leave on full all the time, to act as a bypass? At the very least, you could set of the others at a higher shut-off temperature than the faulty one.
Softus,
In answer to your question, yes there are trv's on every radiator & also the noise does stop when i either open or close the trv so i presume it must be a bypass problem?
I'm away from home at the moment but will check the hose under the floor & get back to you on Monday.
In answer to your question, yes there are trv's on every radiator & also the noise does stop when i either open or close the trv so i presume it must be a bypass problem?
I'm away from home at the moment but will check the hose under the floor & get back to you on Monday.
That's funny, I thought someone would say that there should be at least one rad with no TRV on it, in the same room as the wall thermostat. Otherwise when all the TRVs have closed down the room stat might still be trying to run the heating because it thinks the room is not up to temp.
(If all your rads have TRVs you can also achieve this by removing the thermostatic head from the nearest rad to your wall 'stat.
Once you've done that, the room stat will turn off the heating when the house is warm, and the pressure will always be able to ecape via that last open rad.
(If all your rads have TRVs you can also achieve this by removing the thermostatic head from the nearest rad to your wall 'stat.
Once you've done that, the room stat will turn off the heating when the house is warm, and the pressure will always be able to ecape via that last open rad.
Softus,
I had a look under the floor at the weekend & the "bypass" consisits of a plastic piece of tubing between 2 adjacent pipes running under the floor, connected in to each using a tee piece; in the piece of tubing there is a metal insert piece which seems to have an adjustment screw on the side of it.
Would that fit in with your guess as to what it may be.
Sure enough I tried opening up the bathroom thermostat to full which certainly seemed to reduce the noise if not get rid of it; I'm wondering whether to remove one of the trv's but am unsure as to the significance
Any advice would be much appreciated.
I had a look under the floor at the weekend & the "bypass" consisits of a plastic piece of tubing between 2 adjacent pipes running under the floor, connected in to each using a tee piece; in the piece of tubing there is a metal insert piece which seems to have an adjustment screw on the side of it.
Would that fit in with your guess as to what it may be.
Sure enough I tried opening up the bathroom thermostat to full which certainly seemed to reduce the noise if not get rid of it; I'm wondering whether to remove one of the trv's but am unsure as to the significance
Any advice would be much appreciated.
Memory about this problem has faded a bit. Are you saying that the pipe is plastic, not rubber? If so, then perhaps it is a bypass after all.
I'm not clear what you mean by a "metal insert". This could be a ball-o-fix valve with a slotted spindle, but could be something else. Does it look anything like this:
If so, then which way is the slot pointing on your valve?
I'm not clear what you mean by a "metal insert". This could be a ball-o-fix valve with a slotted spindle, but could be something else. Does it look anything like this:
If so, then which way is the slot pointing on your valve?
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