Really loud noise from Baxi Duotec 28kw when draining hot water

spinningsheep

Hi, hope maybe someone can shed some light on this, we had a Baxi Duotec 28kw fitted on Thursday, all has been great, house is toasty warm and have lashings of piping hot water on demand. The boiler just ticks over when it is on from the timeclock, very gentle plume coming from flue, seems to be condensing nicely, I had a bath on Thursday night and the boiler fired full tilt as expected and made very little noise. Last night, I opened the kitchen tap to fill the bowl for the dishes and the boiler fired up but started making the worst vibrating growl noise which got worse the more I opened the tap, it doesn't do this when the boiler is just providing the heating to the radiators. I have been running the radiator water temp at 60-65, so just to see if it only happened when trying to use hot water, I turned this dial on the boiler to max, 80degrees, and the boiler fired on full power as expected and started to make the exact same noise. I phoned the installer who is going to pop round tmrw lunchtime, he seems to think it may be the magnaclean filter fitted above the boiler on the return flow may be full of gunge again as a result of the chemical flush they did. It has already been emptied once but he says there may well still be lots of sludge coming through the system after being dislodged by the flush? Does this sound right?

gas4you

If the system has had a half decent flush, I wouldn't expect the Magnaclean to be full again this quick.

The sound you get, to me, sounds like sludge/crap has got into the bottom of the heat exchanger coil.

This is a very common problem with all Giannoni heat exchangers when fitted on a dirty system.

The boiler main HE will probably need reverse flushing to clear it.

Canucklehead

Hi...does this 'noise' occur with every HW tap in the property?

GSR

spinningsheep

Yes canucklehead both the bathroom hot tap and the kitchen, and as I said when you increase the temp of the radiator water to 80 (MAX) and the boiler has to work harder.

spinningsheep

Installer has been out and thinks it may be the fan or its housing. Baxi engineer coming on friday morning. Hopefully will sort it. Landlady is fuming, old boiler was 25 years old and not a days trouble from it, this one has been in less than a week and already the engineers are out!

spinningsheep

Well its sorted itself out, cancelled the engineer. It seems something may have been lodged in there maybe and it's cleared itself, purrs like a kitten now.