Potterton Puma whine

[Bogbeast]

Hi,

I have a Potterton Puma Combi boiler (not sure of exact model) that's been making horrible wailing noise when running in central heating mode. What seems to happen is that once the boiler gets to a certain temperature there's a constant loud whine (more like a banshee wail!) that can be heard throughout the house. This sometimes persists for a short while after the thermostat reaches temperature and cuts out the boiler.

I have wonderful "3 star" (!) British Gas service contract and they've looked at it a couple of times. The hot air extraction fan has been replaced which seemed to cure the problem for a couple of days but now it's come back. Another engineer told me it wasn't too bad and that "all boilers make a bit of noise"!!

I'm starting to think that this might be a pump problem since it only happens in central heating mode and not when running the hot tap. However, given that the noise only starts when the boiler warms up, could there be a metal plate somewhere that's vibrating at resonant frequency and causing the noise?

Any help will be gratefully received,

Michael

 

[snes]

Might want to try replacing the diverter valve rubber ball - the repair kit only costs £3. After some years (especially if you have additives in the system) these balls lose their sealing ability, hence the strange noise you mentioned. Happened a couple of times to my Lynx boiler - I presume you have the same Honeywell diverter valve fitted.
Good luck!

 

[ChrisR]

He hasn't got a honeywell diverter and the honeywell kit costs a lot more than that.

The pump runs as hard for HW as CH . It could be diverter related, but it isn't a "known" whine as far as I'm aware, unlike some other boilers. I'd be in there with a wooden stick to listen with. A hammer works quite well (ear on metal end!)

 

[weargas]

wait for it to start the whine and then turn the pilot button to the pilot light setting. this will stop the main burner firing. if the noise stops almost immediately there's a very good chance it's a scaled heat exchanger. if the noise continues then it's mechanical (pump, fan etc). if you haven't got a pilot button then your boiler is electronic ignition. if this is the case you could get someone to turn the gas off at the meter during the whine.

 

[Bogbeast]

Thanks for the replies so far. I think I'll try and work out how to get the main cover off while it's running and see if putting light pressure on any points inside gets rid of the noise. My gut feeling is that it's a panel vibration rather than the pump since this has been happening for over a year with no real adverse affect. Yeah, I know I should have sorted it earlier, but I just couldn't get the time off!

Think I'll wait until after Christmas before I mess about with it. Don't want to knacker the system just as the cold weather and snow hit. Chris I note your idea of the hammer and I'd thought of something similar, only it involved hitting the boiler ver hard with it.

Michael