I've got a fully-pumped gas CH & HW system. My problem is that the boiler
fires even when the control unit (timer) says that both the CH and Hot water
are off. I don't have a separate frost thermostat (unless its built-in to
the boiler - a British Gas "F2"). A British Gas engineer did call, and
replaced a motorised valve motor, but that made no difference at all.
I was under the impression that the valve could not operate the boiler
unless the timer was in the "on" position. The BGas engineer said that I was
wrong (and he's the expect, not me) but if he's right, what is the point of
the timer anyway ?
Any suggestions that don't include calling in British Gas would be greatly