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Vaillant boiler noise after British Gas visit

B

blueplanet

Hello I have a Vaillant Eco Fit Pure 418 boiler. It was installed in 2021 and was not used mush for one year. It has been used since but I am a very low user and I had a solar thermal system until last year so the boiler has seen minimal use.

More or less when it gets cold I get two fault codes F.83 and F.72. The system is mains pressured with an unvented cylinder. The boiler was in excellent virtually new condition. It operated quietly and efficiently and I could barely hear it when on. I called British Gas due to the two fault codes and they could not identify the cause of the fault codes.

The engineer opened up the front case, and removed the black pipe on the left side to access something. Other than that I do not know what else he did. I do know he adjusted the temperature control on the cylinder and turned it up to 60c.

However, after he left the boiler is now noisy. It makes a constant humming and whirling sound. Before when it switched on it would power on, display an egg timer and about 20 seconds fire up but remain nice and quiet when running.

Now, it powers on and fires up quickly, with what sounds like perhaps a fan running constantly, it makes this noise continuously while operating, the fan (or whatever it is) seems to run for about 2 minutes after it switches off. The noise is irritating and at night prevents me sleeping (bedroom above boiler).

Any idea on what has caused this or what the issue is likely to be? I've raised it with British Gas and then are to send someone else over but that is taking time. Thanks in advance.
 
Can you check the flow/return temps, D.40/D.41 preferably with the boiler off.
Could be a flow or return sensor fault, surely they tested the resistances of both?.
Does the circ pump run as soon as you start up?.

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I will check and confirm the D40/D41.

BG attended again today and could not locate the issue. The engineer did say he had checked the flow and return though. He has ordered the following parts simply to eliminate them (although he says they seem to be fine) as the cause:

H28706 Sensor NTC C/H 2
738133 PCB 1
 
John.g said:
And, of course, the obvious, if a OV system, check F&E cistern has water in it, and if pressurized to 1.0/1.5bar if sealed.
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Its a sealed system, unvented cylinder running off the mains. The flow return temperature when off were: D40 - 24c and D41 - 19c. The pump comes on when the boiler is switched on but before it fires up if that makes sense. Also the pressure is correct at around 1.25 bar. Thanks for your help.
 
blueplanet said:
Its a sealed system, unvented cylinder running off the mains. The flow return temperature when off were: D40 - 24c and D41 - 19c. The pump comes on when the boiler is switched on but before it fires up if that makes sense. Also the pressure is correct at around 1.25 bar. Thanks for your help.
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Yes, quite normal for the pump to come on before fire up. Not sure if you mean (from the below) that the boiler does run continuously and the noisy operation carries on for a further 2 minutes?, a normal, programmed off or roomstat/cylinderstat satisfied off means the circ pump will run on (pump overrun) for whatever its setting is, (D.01), I think the fan runs on for maybe 10secs or so as well but not sure.
Can you alternatively check between D.40/D.41 a few times while the burner is firing.

"Now, it powers on and fires up quickly, with what sounds like perhaps a fan running constantly, it makes this noise continuously while operating, the fan (or whatever it is) seems to run for about 2 minutes after it switches off. The noise is irritating and at night prevents me sleeping (bedroom above boiler)."
 
I ran the boiler for about 30 mins. The D40/D41 readings (once heated up) were consistently D40 - 57 and D41 50. Occasionally, 57 and 49.

It terms of the noise since the BG engineer attended the boiler has been noisy.

Before: It was quiet, it would turn on and then for about 15 seconds remain you would see an egg timer but it would not ignite the gas. Then it would ignite the gas and then continue operating but was quiet. You would not hear the fan going but it worked well. When the boiler reached the programme end (say 30 mins or 1 hour) it would turn off.

Now: when you turn it on the gas seems to ignore almost instantly. however, as soon as it goes it seems like the fan starts and you hear a constant humming or whirling sound. Its very annoying and the boiler is now not quiet. On the bedroom above you cannot sleep because of the noise. When the programme reaches the end of the 30 min or 1 hour the fan seems to operate for about 2 minutes afterwards.
 
blueplanet said:
I ran the boiler for about 30 mins. The D40/D41 readings (once heated up) were consistently D40 - 57 and D41 50. Occasionally, 57 and 49.

It terms of the noise since the BG engineer attended the boiler has been noisy.

Before: It was quiet, it would turn on and then for about 15 seconds remain you would see an egg timer but it would not ignite the gas. Then it would ignite the gas and then continue operating but was quiet. You would not hear the fan going but it worked well. When the boiler reached the programme end (say 30 mins or 1 hour) it would turn off.

Now: when you turn it on the gas seems to ignore almost instantly. however, as soon as it goes it seems like the fan starts and you hear a constant humming or whirling sound. Its very annoying and the boiler is now not quiet. On the bedroom above you cannot sleep because of the noise. When the programme reaches the end of the 30 min or 1 hour the fan seems to operate for about 2 minutes afterwards.
Click to expand...
The noise problem and any sensor problems should be unrelated, the dT, 24-19, 4C, boiler off, theoretically should be the same but the boiler may have to be off overnight for this to happen, the dT, 57-50. 7C, boiler running, seems reasonbable enough, but changing the sensors (+the PCB) might show up something, whatever about the noise. issue.
 

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