When the boiler runs in a low fire, it's make a high vibrating noise for 1 minute, then it's working ok, but when the thermostat lighting again, the noise start again. Any idea why? Thank you
sounds like the gas valve just needs adjusting on min setting .to get the gas and air mixture perfect when fisrt firing up ,normally on ch not hw .if you have your 5 yr warranty still fone ferroli o8715592924
ferroli engineer, May 2010
i would suspect the gas mixture is incorrectly setat minimum output. It will either require adjusting or possibly a new gas valve
