I have just moved into a new house and boiler has been working fine. I have just started using the heating, and when the water gets hot and the fan is running at high speed the boiler starts to make a horrendous howling sound. The boiler also does the same if selected to heat hot water and set to a high temperature. It sounds to me like the air inlet or flue resonating, but has anyone else had this - or worked out what's wrong?
Thanks.

Steve, September 2009

Hi thanks for that, I should have mentioned the whole system is new, I have checked the flow and return temperatures to the boiler, on full flame the temp is around 15 degC. Ideal have said it should be less than 20.

Steve, September 2009

Could be Two Causes.
1) & most likely Burner noise on high fire (Service Req)
2) Kettling when running at higher temperatures

You should get a RGI to come and identify which it is

www.gassaferegister.co.uk will assist you to find an engineer near to you

www.elanar.co.uk, September 2009