I had the above boiler installed a few months ago. After a while, a high pitched noise seemed to be vibrating through the pipes. We thought that it was the central heating pump had become worn out and was straining. We have just had this replaced, and the noise is still there! The plumber came back and bled all the radiators and said that it was probably air in the system and for us to keep bleeding the system. Obviously did not need a new pump then! The noise is still there, but we can get rid of it if we switch more rads on. Now we are desparate. When the noise came back today, I put my ear to the boiler casing and it seems like it is coming from the boiler. Can anyone help think of why a new boiler would make such a strange noise?
Worcester greenstar oil fired 32/50kW condensing boiler
- Thread starter suzen
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What model of circulating pump do you have?
It may be set too high for when most radiators are off. It is possible to get auto-sensing pumps now which regulate the flow pressure at a constant level, so if the bypass is opening, it would reduce the likelihood of this happening.
It may be set too high for when most radiators are off. It is possible to get auto-sensing pumps now which regulate the flow pressure at a constant level, so if the bypass is opening, it would reduce the likelihood of this happening.
The pump is Smedegaard. We replaced like for like. It has three settings and we have set it to number 2. It doesn't seem to make much difference which setting it is on. The noise comes regardless.
I really think it is coming from the boiler. it has a pitch that when you turn a radiator up or down it changes.
I wish you were able to come and see it for yourself! These things are so hard to explain. The installer and the plumber who came to fix it seem to be at a loss!
I really think it is coming from the boiler. it has a pitch that when you turn a radiator up or down it changes.
I wish you were able to come and see it for yourself! These things are so hard to explain. The installer and the plumber who came to fix it seem to be at a loss!
The Bypass pipe is one which should be fitted after the pump with some kind of valve on it then connected back into the return back to the boiler.
The bypass's spec should be in the manufacturers instructions, eg length and diameter etc
When there are a small amount of radiators on, this pipe alows an easy route for the CH water,taking the strain off the system allowing the water to flow away from the boiler preventing overheating....or strange noises.
Your boiler is quite a large output and for it to be firing at full whack only servicing 2 radiators it sounds like its too hot and complaining about it!
You could as suggested get worcester back to it and they may explain that it needs this bypass and then the next port off call is your installers.
The bypass's spec should be in the manufacturers instructions, eg length and diameter etc
When there are a small amount of radiators on, this pipe alows an easy route for the CH water,taking the strain off the system allowing the water to flow away from the boiler preventing overheating....or strange noises.
Your boiler is quite a large output and for it to be firing at full whack only servicing 2 radiators it sounds like its too hot and complaining about it!
You could as suggested get worcester back to it and they may explain that it needs this bypass and then the next port off call is your installers.
Thank you for your reply.
I shall be in touch with Worcester. Although last night, I put all the rads on - they are all individually thermostatically controlled. The noise was still there. so we we had to turn everything off!
It doesn't seem that we have a pass by pump...
I shall be in touch with Worcester. Although last night, I put all the rads on - they are all individually thermostatically controlled. The noise was still there. so we we had to turn everything off!
It doesn't seem that we have a pass by pump...
I am really trying to understand about central heating systems. The noise only comes when the heating is switched on. We have the water on 24hr and there is never any noise when just the water is on. Therefore, it must be to do with the CH. The circulatory pump is new, (last week) so presumably it can't be that either. We keep bleeding the rads, and taking air out, so although there seems to be some air in the system, it is minimal. The installer and the plumber who fitted the pump both drained the sysmem as well. So that should be ok.
What's left that can make a noise? The note of the whine/whistle changes according to the amount of rads that are on. I know noises vibrate through the pipes and stuff, but if you put your ear to the boiler, it definitely seems to be coming from there.
What's left that can make a noise? The note of the whine/whistle changes according to the amount of rads that are on. I know noises vibrate through the pipes and stuff, but if you put your ear to the boiler, it definitely seems to be coming from there.
I am not familiar with your boiler but assume its a heat only and you have an external pump and at least two or ( should be ) more motor valves ( often metal boxed with Honeywell on them ).
In that case it would seem that the flow through your boiler on heating is insufficient. Was the system power flushed or otherwise properly cleaned when the new boiler was fitted?
You could check that by measuring the difference in temperature between the two boiler pipes. There should be 10-20 °C difference! If its more than there is insufficient flow.
What effect does it have on the noise when you put the pump on setting 3 ?
I am not familliar with your pump either! How many watts does it show on the data plate. A standard domestic pump is less than 90w but yours should be much more for your size of boiler.
I would still expect your boiler to be oversized unless you have a lot more than 20 rads or they are all quite big. Most rads are only about 1.5 kW which would give a total heating load on only 30 kW. Oil boilers dont modulate and just have to cycle on/off which makes them less efficient.
Your boiler would be off for 40% of the time even in the coldest weather if the rads are sized as I suggest!
If I was designing a system for you then I would have used two small boilers as this would give redundancy and much greater efficiency when heating only water for half the year.
Tony
In that case it would seem that the flow through your boiler on heating is insufficient. Was the system power flushed or otherwise properly cleaned when the new boiler was fitted?
You could check that by measuring the difference in temperature between the two boiler pipes. There should be 10-20 °C difference! If its more than there is insufficient flow.
What effect does it have on the noise when you put the pump on setting 3 ?
I am not familliar with your pump either! How many watts does it show on the data plate. A standard domestic pump is less than 90w but yours should be much more for your size of boiler.
I would still expect your boiler to be oversized unless you have a lot more than 20 rads or they are all quite big. Most rads are only about 1.5 kW which would give a total heating load on only 30 kW. Oil boilers dont modulate and just have to cycle on/off which makes them less efficient.
Your boiler would be off for 40% of the time even in the coldest weather if the rads are sized as I suggest!
If I was designing a system for you then I would have used two small boilers as this would give redundancy and much greater efficiency when heating only water for half the year.
Tony
Yes, there is an external ciirculatory pump, but I don't know about motor valves. I can't see anything that looks like what you suggest.
Yes, the system was cleaned when the boiler was fitted (well, the installer wrote down on the warrantly that it was!)
I measured the temperature of the two pipes, one at the top and one at the bottom of the boiler. Probably not accurately, but one was about 55 degrees and the other was 35 degreesC.
There is no real difference with the pump on setting 3. The noise might disappear but once you start turning rads up/down or on/off it comes back.
I can't see any watts on the name plate of the pump - only max working pressure = 10bar and 50hz. (Also it cost £150 and same to install so it better be the right one!).
I counted up our rads - we have 23 total. But about half of them are on at any one time. Some are fairly large, but most are medium size.
I wish you had designed our system - I sit here listening to the whistling/high pitched droning noise as I write...
Yes, the system was cleaned when the boiler was fitted (well, the installer wrote down on the warrantly that it was!)
I measured the temperature of the two pipes, one at the top and one at the bottom of the boiler. Probably not accurately, but one was about 55 degrees and the other was 35 degreesC.
There is no real difference with the pump on setting 3. The noise might disappear but once you start turning rads up/down or on/off it comes back.
I can't see any watts on the name plate of the pump - only max working pressure = 10bar and 50hz. (Also it cost £150 and same to install so it better be the right one!).
I counted up our rads - we have 23 total. But about half of them are on at any one time. Some are fairly large, but most are medium size.
I wish you had designed our system - I sit here listening to the whistling/high pitched droning noise as I write...
I cannot immagine that every one of your radiators is 4 kW !
A typical bedroom is rated at 1-1.5 kW.
I am of the opinion that your boiler is considerably over rated but nevertheless the designer has to cater for the time when its -1° outside and ALL the rooms are occupied !
Your differential temperature implies to me that the flow rate is seriously too low! It should improve when the pump is put on setting 3.
Whats the differential with most of the rads on?
What guide differential temperature does the boiler manufacturer reccomend in the boiler/installation manual?
You should do these tests with the hot water reheat off so that it does not interfere with the results.
Tony
A typical bedroom is rated at 1-1.5 kW.
I am of the opinion that your boiler is considerably over rated but nevertheless the designer has to cater for the time when its -1° outside and ALL the rooms are occupied !
Your differential temperature implies to me that the flow rate is seriously too low! It should improve when the pump is put on setting 3.
Whats the differential with most of the rads on?
What guide differential temperature does the boiler manufacturer reccomend in the boiler/installation manual?
You should do these tests with the hot water reheat off so that it does not interfere with the results.
Tony
I found the installation completion report and the installer has noted the differential across the flow and return as 10 °c.
That is probably more accurate than my reading I would think.
Ok. Assuming my rads average 1kw and I have 23. That's 23kw load ( I assume). What about water heating? Doesn't that have to contribute to the load?
I am sure on average we would only have on about 8 rads at any one time. Perhaps the installer should have asked us a few questions I suppose about load.
We tried putting the pump up to three this morning, but there is no noticeable difference. I suppose it wouldn't really matter in a domestic house, but in a guest house you don't want guests irritated by the sound of whistling.
I phoned Worcester who will come out on Friday. Although by what you say, it isn't really a fault of the boiler - just underuse?
That is probably more accurate than my reading I would think.
Ok. Assuming my rads average 1kw and I have 23. That's 23kw load ( I assume). What about water heating? Doesn't that have to contribute to the load?
I am sure on average we would only have on about 8 rads at any one time. Perhaps the installer should have asked us a few questions I suppose about load.
We tried putting the pump up to three this morning, but there is no noticeable difference. I suppose it wouldn't really matter in a domestic house, but in a guest house you don't want guests irritated by the sound of whistling.
I phoned Worcester who will come out on Friday. Although by what you say, it isn't really a fault of the boiler - just underuse?
Water is allowed for at only 2 kW for a domestic house because its quickly heated up and then goes off. In your case one might allow 6 kW for full occupancy but that still leaves your boiler as seriously over rated and with inefficient operation with deep cycling.
Even so your system should operate acceptably if there is adequate flow and all the indications are that there is a restricted flow through your boiler!
Tony
Even so your system should operate acceptably if there is adequate flow and all the indications are that there is a restricted flow through your boiler!
Tony
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