hi ... just had chemical flush on a system with gloworm 18hxi boiler and magnaclean fitted. When heating up system makes a whistling or more precisely a nice musical note like a flute for a couple of seconds just after the boiler modulates (I think thats right .. just as it turns down after maximum gas heat). Can kill the sound just by tapping on the side of the boiler as it appears... no problem with seal to boiler cover. most of the noise is radiated out through the flue which must be driving neighbours mad Any ideas
Most likely the fan but possibly the pump. Cannot see how the flush would have caused this unless the boiler was opened up. Make sure the boiler casing screws are all tight. If you can stop the noise by 'tapping' against the boiler case, try wedging it with something for now until you can identify the source.
thanks for reading and the responses... much appreciated ... not the pump as its seperate. will see if can isolate sound to the fan