In This Guide
Why does my heating timer need resetting?
The most common reason is a power cut. When the power drops, even briefly, many older programmers lose the time, so the clock is wrong and the heating fires at the wrong points in the day. The same happens if the backup battery in the programmer has died. Resetting the clock and rechecking the schedule usually puts it right.
Other times you simply want to change when the heating comes on, or the clocks have changed for British Summer Time and the timer has not followed automatically. In all of these cases the fix is the same: set the correct time, then set your on and off periods.
How to reset a digital programmer
Digital programmers vary by make, but the principle is consistent. Set the clock first, usually by holding a clock or set button and adjusting with the plus and minus keys, then confirm. Next, set your heating periods, typically by selecting a program slot and entering an on time and an off time for each. Many programmers let you copy the same schedule across weekdays and set a different one for the weekend. If yours has an override or boost button, that turns the heating on temporarily without changing the program.
If the display is blank or the settings will not hold, the programmer’s backup battery may need replacing, or the unit itself may have failed.
How to reset a mechanical timer
A mechanical timer has a rotating dial marked with the 24 hours. Set it by turning the dial to the current time against the marker. You set the heating periods using the small pins, tappets, or segments around the edge: pushed in (or out, depending on the model) for on, and the opposite for off. There is usually a switch to select timed, always on, or always off. Because there is no clock to lose, mechanical timers mainly need resetting when you change the schedule or the clocks change.
What if resetting the timer does not work?
If the timer is set correctly but the heating still will not come on when it should, the problem may not be the timer at all. A boiler that ignores a correct schedule can point to a fault with the boiler, the wiring, or the controls rather than the programmer. If your heating will not respond despite a correct time and schedule, our guide to a boiler on but no heat to the radiators covers the other causes worth checking, and 0800 Homefix can diagnose the controls if you would rather have it looked at.
How 0800 Homefix can help
Most timer resets are a two-minute job once you know your controller. When the heating will not respond to a correctly set timer, 0800 Homefix are Gas Safe registered engineers covering London and the South East who can find whether it is the programmer, the wiring, or the boiler and put it right. A faulty programmer or a control fault is straightforward for an engineer to diagnose. You can see the full service on our boiler repair page.
0800 Homefix charges as the first hour of labour, paid in advance, with any parts or further work quoted and agreed with you before it begins. For current rates, see our rates page. Our labour is guaranteed for 12 months, and any parts we fit are covered by the manufacturer’s 12-month guarantee.
Frequently Asked Questions
Why is my heating coming on at the wrong times?
Usually the clock on the programmer is wrong, most often after a power cut or when the clocks change. Reset the current time, then check your on and off periods are correct.
How do I reset my heating timer after a power cut?
Set the current time first, as the power cut will have reset or lost the clock, then re-enter your heating schedule. If the clock will not hold, the programmer’s backup battery may need replacing.
My heating timer is set correctly but the heating won’t come on, why?
If the schedule is right and the heating still does not respond, the issue is likely the boiler, wiring, or controls rather than the timer, which needs a Gas Safe engineer to diagnose.
Do mechanical and digital timers reset differently?
Yes. A digital programmer needs the clock and schedule set with its buttons, while a mechanical dial is set by turning it to the correct time and adjusting the pins or tappets for on and off.
Helpful resources
- Energy Saving Trust: guidance on heating controls and using them efficiently.
- Gas Safe Register: check an engineer is registered for control or boiler faults.
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