i have a potterton suprima and when the heating fires up the boiler makes a loud humming noise only when heating is on. when just water on it fine no noise any ideas any one thanks?

andrew h, February 2009

My boiler started doing this and it turned out to be the Fan that extracts the carbon (what ever) out of the chimney. As this is poison it eventually shut down as a safety measure. After calling a heating firm they had to order a new fan, monday, which was delivered to them Wednesday and is being fitted tomorrow Thursday. Cost around £290. May take out Maintenance Contract for £110 also.

Joan and Tony Bradley (aged 65), February 2009

try turning the pump speed up and slightly lowering the boiler thermostat

mike, February 2009