Hi,
My gas boiler has started making what I can only describe as a mechanical buzzer sound. It appears to happen randomly when the boiler thermostat kicks it back into life. Time the boiler has been on for doesn't seem to make a difference, sometimes it takes hours of use before it does it, sometimes it's barely been on.
Anyone got any ideas? Listening to the boiler when it is running, it does have a faint hum that sounds to be at the same frequency as the louder buzzer sound. It's a sealed system, with 'Classic' on the casing (no idea on the 'brand'), with a fanned flue
I'd rather have some idea what it could be before I get bamboozled by a plumber.