My central heating is always on! We have a timer clock that should turn it on twice a day, however, if I turn the thermostat up when the heating should be off, it still comes! I have changed the timer clock as recommended by a plummer but it still doesn't work properly. Can anyone help?? :confused:

Are you talking about a programmable therostat or actually some sort of clock? Programmable stats are over ridden when you manually raise the temp.

Do you mean the furnace is running all the time, or just that the thermostat can kick the system on any time? It would be possible to wire a timer in so that either could turn the heat on, or that both it and the thermostat would have to call for heat to get heat.