We have an ideal mexico boiler for our HW and CH, it is controlled by a switchmaster sm400 timeclock, one of the old mechanical ones. The odd thing is that when the timeclock is not programmed to provide heat or hw the boiler will turn on if we use hot water. We have also noticed that in the evenings when the room stat controls the temperature, after the initial couple of hours, we can put the stat up a degree and and nothing happens for a while, not even the circulating pump, but then at 20:50 the system will fire up without fail. Any one have any ideas please?