jo
at the very least there should be a room thermostat in your place that you can turn down at night. If you turn it to say 12 C when you go to bed this will shut the boiler down but still leave enough heat in the system to prevent overnight freezing. On the boiler itself there should be a power switch of some description so that you can turn the boiler off if you have to.
But first. If you have a timeclock on the boiler it is set correctly? have you checked to make sure that the timeclock has not been left set to give permanant 24 hrs of boiler running?
garryk
January 2010