Has your boilers timer broken? What causes this common fault and how can you fix it?
The humble boiler timer is one of those small but mighty components that keeps your home warm and comfortable - automatically.
But when it stops working, your entire heating routine can quickly fall apart.
So, what causes a faulty timer? Can you fix it yourself, or is it time to call in the pros?
Let’s find out…
Boiler old, unreliable and costing a fortune in repairs? Simply answer these questions, get your fixed price and you could get a new one installed as quick as tomorrow.
What is a Boiler Timer?
Older boilers often feature a mechanical timer, which looks like a small clock face surrounded by pins or tabs. You’ll usually find it on the boiler’s front panel.
Each pin corresponds to a specific time of day - pushing pins in or out determines when the heating or hot water turns on or off.
👉 Tip: Make sure your boiler is set to “timer mode” (not “on” or “off”), or it won’t follow your set schedule.
Modern boilers, meanwhile, use digital timers or smart programmers. These come with small screens, buttons, or even app control, making scheduling more intuitive and accurate.
In all cases, check your manufacturer’s manual for exact instructions - layouts vary between brands and models.
Why Is My Boiler Timer Not Working?
There are several possible culprits, ranging from simple DIY fixes to issues that need a qualified heating engineer.
Below, we’ll run through the most common causes and how to deal with each.
The boiler Fuse Has Tripped
Image showing boiler fuse / Heatable
DIY-Friendly? Generally, yes
One of the more common reasons for a boiler timer malfunctioning is that the boiler fuse has tripped.
This would occur at the fuse board which manages the electricity supply for your household.
You can check whether this is the case by going to your fuse box.
Assuming you know where the boiler fuse is, you can check if it’s facing down. Of course, if you don’t know what fuse to look for, hire an electrician.
However, if you know what fuse to look for and it is down, you now know that the fuse related to your boiler has tripped.
Flip it back up and your boiler should regain power, and, in turn, the timer should work as normal again.
If you find that this hasn’t fixed the problem and if you have a modern boiler timer, it’s possible that the fuse has blown.
Return to your fuse box and turn off the power at the mains (for your entire household). Then find the fuse that relates to your boiler.
If you have the right skills and knowledge, you may remove the fuse with an electric screwdriver before replacing it with a new fuse.
Make sure to purchase the correct replacement fuse. You can turn the power off once everything is complete and safe.
Again, if in any doubt, hire a professional. If after all of the above, the issue still hasn’t been solved then something else is going on and you should hire a professional either way.
🎥 Watch next: Gas engineer Allen Hart explains the most common boiler faults and how to fix them on the Heatable YouTube channel.
You Forgot to Change the Clocks
DIY-Friendly? Yes
One possible cause of a boiler timer not working that’s easy to overlook is that you didn’t adjust the time on your boiler.
Old boilers usually require that you turn the physical timer/clock an hour forward or back to account for when the clocks change.
Many modern boilers will do this automatically but if you have an older boiler, don’t forget to do this manually.
If you forget to change the clocks, you’ll notice that your heating or/and hot water are suddenly turning on and off at the wrong time, specifically that they are off by an hour.
Power Cut Caused a Boiler Reset
DIY-Friendly? Yes
If your home recently experienced a power outage, this could have caused issues with your boiler and thus the boiler timer.
More specifically, power cuts can reset your boiler timer, thus you’d need to set your boiler timer again.
The thermostat Has Been Set Too Low
Image showing typical boiler thermostat / Heatable
DIY-Friendly? Yes
If you’ve got a combi boiler, it could be that your thermostat temperature is set too low for the system to activate.
Try raising it slightly - usually, 18–21°C is the sweet spot for comfort and efficiency.
If nothing changes, it’s worth checking your thermostat batteries or positioning (it shouldn’t be in direct sunlight or behind furniture).
Zone Control
DIY-Friendly? Yes
If you have a combi boiler, it may feature zone control which allows you to set parts of your heating system to turn on and off based on your needs.
You may need to adjust the timer setting that relates to zone control to make sure it is working correctly.
Again, if you suspect this could be the issue at play, check how to solve it by following the manufacturer’s instructions.
The Boiler Timer Is Broken
DIY-Friendly? No
Lastly, the boiler timer may simply be broken and beyond repair.
In this case, you’d need to hire a qualified heating engineer to replace it.
This may cost somewhere in the region of £100 to £200.
It is also possible that a heating engineer upon determining what’s wrong with your boiler may discover other underlying problems which could lead to more expensive repairs, although it’s not the most likely outcome.
Resetting a Mechanical Boiler Timer
If your boiler has a traditional clock-style timer:
Turn the dial clockwise until the correct time aligns with the pointer.
Push the outer pins in or out to set on and off periods.
Switch the boiler mode to “timer” rather than “on” or “off”.
That’s it - your heating should now follow the schedule.
Resetting a Digital Boiler Timer
For boilers with digital or LCD screens:
Check the displayed time is correct (and in the right AM/PM format).
Use the menu or “set program” button to enter your heating schedule - weekdays and weekends often have separate options.
Confirm or “run” the program to activate it.
If your timer frequently resets, consider adding a small backup battery (if your model supports one).
Get a Quote for a New Boiler Today
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To learn more about boilers, visit our advice section, check out our YouTube channel, or read customer testimonials here.
