Noise From Boiler - Opinions Please

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Any help identifying the following noise from my boiler, please? Ignore the water, that's just my nearby kitchen tap.

It sounds like an airplane. Happens about 30 seconds after running water from boiler when at rest.


I have had British Gas out 4 times (Home Care) and they have replaced injector valve, gas valve and fan, but noise still occurring. I was basically told by the guy today that he's ran out of ideas so don't bother phoning back up... However, I don't really have much choice.

Annoyingly it only happens if the boiler hasn't been on for 30 mins or so which makes it hard to troubleshoot for the engineer when he's here. It's most noticeable in the evening when I get home and first thing in the morning when I get up.

It's an Ideal Logic Combi 35.
 
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Firstly don't be fobbed-off by BG, keep at them until they get someone (else) out who can properly diagnose the noise.

Does the noise stop as soon as the hot water stops flowing?
Does the noise only occur when certain taps are in use, or are there taps which can be used and the noise never occurs?

Good symptom reporting = fast and accurate diagnosis.

Surely you can avoid using hot water for a few hours before BG get there if it'll better illustrate the problem?
 
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Firstly don't be fobbed-off by BG, keep at them until they get someone (else) out who can properly diagnose the noise.

Does the noise stop as soon as the hot water stops flowing?
Does the noise only occur when certain taps are in use, or are there taps which can be used and the noise never occurs?

Good symptom reporting = fast and accurate diagnosis.

Surely you can avoid using hot water for a few hours before BG get there if it'll better illustrate the problem?

It definitely happens with all taps - kitchen, bathroom and also central heating. And yes, when the hot water is stopped, the noise stops.

And yes, we have been avoiding using hot water before they arrive - however, they then spend an hour running hot water so at the end of the visit, all looks well from their point of view. An hour or so later it's just back to how it was.
 
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But you said it occurs 30 seconds after the (let's assume cold) boiler is used for hot water, so surely BG will hear it for themselves?

In isolation my opinion is that the noise is burner generated, and I would have BG set the gas-air ratio to the manufacturer's recommendations (especially the CO2 concentration at high fire).

Does it affect the occurrances of this noise if the heating has been on prior to first hot water use?
 
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But you said it occurs 30 seconds after the (let's assume cold) boiler is used for hot water, so surely BG will hear it for themselves?

In isolation my opinion is that the noise is burner generated, and I would have BG set the gas-air ratio to the manufacturer's recommendations (especially the CO2 concentration at high fire).

Does it affect the occurrances of this noise if the heating has been on prior to first hot water use?

They do hear it during the initial test, but then they never really give the boiler time to "cool" as they run water non-stop for the next 30 minutes, so it's never clear if it's fixed.

If the heating is on first then the noise occurs within the first 30 - 60 seconds of the heating being on. Then you can run the water without occurrence until the heating is off and the hot water hasnt been used for ~30 minutes.
 
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Sounds like main hex kettling. Will be hotter during water use as 35kw going through it. If fan, Venturi and injector and burner done then that’s all that’s left.
Heating ok? If so I’d be looking at main hex could also possibly be bypass but never really heard it on hw.
Edited to add I don’t think Venturi has been changed. tell BG you want them to pay to get the manufacturer out to repair it as you have lost faith in their engineer
 
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But you said it occurs 30 seconds after the (let's assume cold) boiler is used for hot water, so surely BG will hear it for themselves?

In isolation my opinion is that the noise is burner generated, and I would have BG set the gas-air ratio to the manufacturer's recommendations (especially the CO2 concentration at high fire).

Does it affect the occurrances of this noise if the heating has been on prior to first hot water use?
You can’t adjust gas valve on ideal boilers. Can only be replaced.
 
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Sounds like main hex kettling. Will be hotter during water use as 35kw going through it. If fan, Venturi and injector and burner done then that’s all that’s left.
Heating ok? If so I’d be looking at main hex could also possibly be bypass but never really heard it on hw.
Edited to add I don’t think Venturi has been changed. tell BG you want them to pay to get the manufacturer out to repair it as you have lost faith in their engineer

Thanks for the advice. Is the manufacturer a real option?

So just to confirm, I believe I have had the following replaced - fan, injector valve and gas valve. I think that's it.

So your two (?) suggested final parts would be the Main Heat Exchanger and/or Venturi (is that a part name?)

Thank you again, really appreciate it. It's getting really frustrating now, it's good to have some other options.
 
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these boilers can have an issue with the burner coming away internally at the rear from faulty welds which cause droning noise/remove and press gently on the plate and if it moves then its faulty.
 
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these boilers can have an issue with the burner coming away internally at the rear from faulty welds which cause droning noise/remove and press gently on the plate and if it moves then its faulty.
really ? please elaborate
 
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these boilers can have an issue with the burner coming away internally at the rear from faulty welds which cause droning noise/remove and press gently on the plate and if it moves then its faulty.
That’s a completely different noise and I’ve only seen it once where burner was cracked and main hex was choked as not serviced in 5 years.
 
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you remove the fan, insert finger to back left side and press down on plate, it should flex a little bit but if it moves its faulty, also happens on icos and isar models, though not as often. seen a couple like this after a technical help video was shown at work.
 
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