The boiler appears to be working okay (in HW mode) but not in CH mode. I have no flashing lights to suggest a fault, but the CH does not come on when the remote thermostat demands it. I noticed that the CH temperature control knob on the boiler turns continuously though. Also, I did manage to get the CH to come on at one point (not sure what I did though to achieve this) but after turning the CH control knob down the CH failed again - it was then that I noticed that the knob continued to turn. Could it be that the knob is broken or could it be that whatever the knob is controling (some kind of thermostat?) is broken? Help!!!