I have a British Gas Condenser boiler which starts making a noise which gets louder then stops duiing the heating process. The engineer is about to change the pump overrun timer as the pump is contiually going even though it is not required. The engineer also serviced the boiler having made some adjustment. Unfortunately it never make the noise when he visits. Has anybody any idea what it could be. Sound like a combustion problem?
if the boiler is a bg 330 it could be the co2 settings are out , usually the low setting is out ,causing a high pitched hum when the boiler has been on a while
