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Unidentifiable Low Frequency Noise Possibly Coming From Boiler - Any ideas?!

Posted: Sun Mar 08, 2015 2:19 pm
by WhitleyMal
We have been suffering from an intermittent, low frequency noise for some months now. The sound is similar to what a diesel engine on the street outside would sound like - a very low, oscillating ‘hum’ and slight vibration. It varies in volume, sometimes seems to pulse – like a pump - and can often be loud and irritating enough to wake us in the middle of the night. We are unable to locate the source, as the sound appears throughout the house and feels as if it’s coming from all around – making us think it could be pipes or the electrical system (although we’ve switched off the electricity and can still hear the hum). It is louder in the loft, where the boiler is located. When it is particularly windy, however, the sound can kick-in extremely loudly and is clearly emanating from the boiler (and becomes less noisy again when the boiler is switched off). I wonder whether this is a result of some sort of back draft into the boiler flue, which is through the gable end wall, though I’ve been told by a plumber that this isn’t possible. The boiler is a Baxi Platinum 40 HE A and was installed in December 2013 – the plumber says he can see nothing wrong with it. We first heard the noise around the time it was installed. I am a lay-person when it comes to plumbing and our plumber is baffled – especially as the noise can occur even when the heating is off (it’s worse or certainly more noticeable in the middle of the night). It is usually no louder at the boiler than in the rest of the loft, except when a gust of wind seems to cause something to happen in the boiler itself. Any ideas would be greatly appreciated, because it’s so annoying and is stopping us sleep and has got to a point where we’re considering moving house to escape it! Thanks!

Re: Unidentifiable Low Frequency Noise Possibly Coming From Boiler - Any ideas?!

Posted: Mon Mar 09, 2015 12:08 pm
by proptech
Hi WhitleyMal
When you had the power off, did you turn everything off at the consumer unit, or just the heating supply ? My first thoughts would be a pump, or a fan somewhere, but if you've turned the lot off !
OK, so you've tried with the power off, and suspect the flue, (I can't see how it could be) but, and it might be a silly suggestion. How about a little experiment - Boiler off, and do something to completely cover the flue for a while, that would at least eliminate it.
Is this a detached house ? if not, what is happening next door. Sorry if that's a bit obvious.

Re: Unidentifiable Low Frequency Noise Possibly Coming From Boiler - Any ideas?!

Posted: Tue Mar 10, 2020 7:22 pm
by scorwi
Hello WhitleyMal
I came across your post from a few years ago as I'm having exactly the same problem with a BAXI 800 that was installed last week. The low frequency humming is driving me insane. Did you ever find the cause of it and if so, how was it resolved? If anybody can offer any suggestions, I'd be so grateful. Thank you!

Re: Unidentifiable Low Frequency Noise Possibly Coming From Boiler - Any ideas?!

Posted: Sun Feb 20, 2022 1:57 pm
by JohnHope
Hi. We have the same noise and situation. Did anyone get to the bottom of it. Was it the boiler flue? Thanks so much!