Central Heating Timer or Programmer Not Working? Common Causes
If your heating and hot water are coming on at odd times, staying on, or not firing at all, the programmer/timeswitch is a common culprit. Here's how to diagnose it.
Blank or frozen display
A dead or frozen screen often means the backup battery or internal supply has failed, or the unit has lost power. Check the fused spur is on and the fuse is intact. If the display stays blank with power confirmed, the timeswitch itself has likely failed.
Heating won't turn off
If heating or hot water runs constantly regardless of the schedule, the programmer's internal relay or a motorised zone valve may be stuck. Try switching to 'off' at the programmer — if nothing changes, the fault is downstream (often the valve actuator).
Wrong times / clock drifting
Times that slip or reset usually point to a failing internal clock or battery back-up. Most modern programmers keep time through short power cuts; if yours no longer does, it's near the end of its life.
No response from buttons
Unresponsive Advance/Boost or programming buttons indicate worn electronics. At this point replacement is more reliable than repair.
Choosing a replacement
Match the number of channels (1 for heating-only or hot-water-only, 2 for both), and decide between a simple timeswitch or a full programmer. If you're unsure which equivalent fits your wiring, send us the model or a photo and we'll confirm the right one.
Need help finding the right part?
Our team has over 80 years' combined heating experience. Tell us what you need and we'll help you get it right.
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