i have a baxi solo powered flue boiler which 'trips ' occasionally when the c/h thermo activates. There is also occasionally a buzzing sound(hunting for power ?) from the honeywell motorized valve on the c/h m/v before the boiler activates . The c/h room thermo is o.k.
The h/w side of the system appears to work 100%.
Can you suggest cause and cure
Thanks. :?