Our vaillant thermomax combi boiler has started making a loud howling moaning noise when heating water. Its fine on the central heating. It had been making a slight kettling type noise for a while when heating water, and occasionally faults with F22 ("dry") even though the pressure is fine. Any ideas ? Thanks, Simon.
Now its starting making what sounds like a dodgy bearings fan noise when on the central heating. Simon.
Noise stops when boiler is turned off. Noise stops if hot water flow is very slow. Something in the secondary heat exchanger vibrating ? Its hard to tell where the vibration is coming from with the cover off. Could be diverter valve. Whole thing needs cleaning out I'm sure. Simon.
Oh, and it also does it when the "stay warm" feature is activating - presumably passing some hot water through the heat exchanger even though there is now flow through the other side of it. Simon.
Our Baxi Megaflo exhibited what sounds like a very similar fault. In our case the vibration wasn't caused by anything mechanical, it was combustion instability at certain degrees of 'modulation' (so like yours it was very dependent on the demand). Took a long time to fix, but eventually succumbed to the engineer adjusting the mixture at the 'low' end of the modulation range.
Richard.
between 40C and 50C if the 'power' is set down (on this system, 50 - 55% is enough) and I would like to stop it.
It involved the use of a flue gas analyzer, so not a DIY job. I think the service engineer was following the manufacturer's instructions, but he said he didn't normally bother checking the 'low' end of the modulation range as it rarely needs adjustment.
Richard.
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charge diagnosis by the hour and you could end up paying more that the boiler is worth to get it fixed. Gas chap thought it might be the pump (at least 100 quid), but there are several issues I think. Boiler is around 10 years old and we are thinking maybe time to get a new one.
Also, it may just be crud in various places but to take the whole boiler apart and clean the pump, heat exchangers etc and flush the whole system would be a right pain. And no hot water whilst you are doing it. No good getting a new boiler and it crudding up again in no time. I would have thought there would be filters to stop stuff getting into the secondary heat exchanger but it is squelching as if there is something (perhaps air ?) in there.
A bit of a rant, but some things just seem more hassle than they should be !
Simon.
When I said "a long time" I meant it took about three visits from a service engineer before he hit upon what was necessary to fix it. They were routine annual services so it didn't cost much more than we would have been paying anyway.
Richard.
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Ah maybe thats where I'm going wrong. No service visits ever in its lifetime ! How much do you pay for a service visit ? Was this a regular arrrangement that might warrant a discount ? Was it "scheme" like British Gas boilersafe or whatever it's called. If he needed spare parts to try and fix it and they turned out not to be needed, did / would you still have to pay for them ? Simon.
Our most recent service was about GBP 75, from a local family firm. I think spare parts are extra, if needed, but our system is fairly new (house built in 2007) so none have been required as yet.
Richard.
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