I put in working order my Celtic RsC Boiler for heating a couple of
weeks ago, and noticed now that no matter where the boiler thermostat
is, temperature goes all the way up to 85 C with high flame when first
switches on, then tries to keep to that temperature with low flame or
no flame at all. But I remember the thermostat did regulate the heating
temperature before, operating also on the flame depending on its
position, but now seems to operate on the max. settings regardless of
its position. Any ideas where could I look into? PCB maybe? Thanks