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Boiler Timer Not Working Correctly? Here’s Why

One of the biggest boiler problems we come across is when the boiler timer isn’t working correctly. Unfortunately, boiler timers tend to develop faults after a few years: they either stop working altogether, or act intermittently, such as randomly turning themselves off.

And in many cases, this issue can look like another part of the heating system that’s malfunctioning. Trust as — this is a problem that you need to diagnose correctly.

So, in this post, we’ll examine the typical symptoms, causes, and fixes of boiler timers malfunctioning.

Boiler timer not working


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Your Boiler Timer Should Work Like This

If you are running a combi boiler, the second you turn on a hot tap, shower or heating, the boiler should produce hot water.

If the boiler timer isn’t working correctly, you could be experiencing a range of problems, such as:

  • The boiler is working but there is no heat to the radiators
  • Your boiler isn’t working or firing at all
  • The boiler turns on and then straight off again
  • The heating is always much hotter/colder than it should be

There’s a big problem here, though — a lot of these symptoms can point to other issues than faulty central heating timer clocks.

A couple of these include:

  • Central heating system is full of sludge
  • Ignition leads are broken and need replacing
  • There is a fault with the PCB (printed circuit board) on the boiler
  • The thermostat is not fitted in a suitable location, or is faulty

These Are Common Boiler Timer Faults

To help determine if it is the clock that’s playing up, see if you recognise any of the following symptoms. If you do, there’s a good chance it’s the boiler timer that is at fault.

  • The boiler timer comes on an hour before, or after, it is supposed to (have the clocks recently gone forwards or backwards? If so, check if the boiler time has been set correctly)
  • The room thermostat is not connecting with the timer, and not telling the boiler to turn on.

Quick Fixes For Broken Boiler Timers

Here are a few fixes you can attempt if you suspect an issue with your boiler timer.

Time Settings

First, check the time on the boiler is correct. If the clocks have changed due to daylight savings (or you’ve had a recent power outage), there’s a good chance the timer clock is incorrect. This can also be the case if you’ve have any recent electrical works carried out in the home, where the electrician has had to move relevant wiring.

Many boilers will automatically reset the clock to midnight.

This could explain any intermittent problems you are having with the boiler (i.e. it comes on at random times).


Next, check whether there is power to the boiler. If your boiler is not working altogether, there’s a good chance there’s been a power cut or there’s a fuse gone in the switched spur. Changing a fuse could solve the problem.

If you do have power, any intermittent problems could be caused from dodgy wiring.

It’s advisable not to mess with any electrics. Either get an electrician or a Gas Safe engineer to come and check this for you.

Thermostat Problems

There’s also the possibility that the thermostat is the culprit, and not the timer.

Central heating timer clocks tend to be built in a slightly more robust manner than the thermostats. The main reason for this is because they are built into the boiler, and quite hard to replace.

Your room thermostat will monitor the temperature of the room. When the temperature drops below your desired temperature, it should kick the boiler into action.

If there’s a fault with the thermostat, it might not communicate with the boiler, or tell it to come on.

Another potential problem is the location of the thermostat. If it’s too close to a heat source (radiator), it will think the room is hotter than it is and turn the boiler off.

Conversely, if the room thermostat is too close to a draught, the thermostat will think the room is much colder than it is and turn the boiler on.

So, if you’ve noticed that your house is a lot colder or hotter than it should be, and you’ve just moved your thermostat, the new location could be causing all the issues.

A middle ground is always a good place to install a thermostat. Consider a location that is:

  • Away from draughts (windows, doors)
  • Far from heat sources (radiators, towel rails, ovens)
  • Not in a room where radiators are off
  • Approximately shoulder height

If you take these considerations into account when installing a thermostat, it’ll work much better.

Heating & Hot Water Settings

This is a pretty obvious one, but make sure you have not turned down the heating instead of the hot water (or vice versa).

Even if you haven’t, there’s a good chance someone else in the house might have done so — we’ve been to more than one property in the past where this was the case.


A lot of boilers and mechanical timers will have a reset switch. So, you can try hitting the boiler timer switch to solve the problem.

Bear in mind, after a reset many boilers will revert to 12-midnight. So, make sure you use the manual and change the time. Otherwise, your boiler will be coming on at extremely random times!

How to Set a Boiler Timer

Wondering how to set the timer on a boiler manually? No worries, resetting central heating timer clocks is simple.

Boiler time - how to set it up

If you’ve got a modern combi boiler, the timer may have any of the following settings:

  • On / 24 hours — the boiler will supply heat until you turn it off.
  • Off — the boiler will not produce heat unless you switch it on manually.
  • Auto your boiler will follow the heating programme you’ve set.
  • All day — you can program the appliance will run until a specified shut-off time.
  • Boost — this setting lets you program a heat boost.

Keep in mind that the terminology may differ depending on the boiler brand and model. The setup procedure will also depend on the type of timer you have — mechanical and digital.

How to Set a Mechanical (Analogue) Boiler Timer

Here’s what you do if you want to set up an automatic programme on your mechanical, or analogue, boiler timer dial.

  1. Make sure your timer is showing the correct time. Just bear in mind that boiler timers typically use the 24-hour clock.
  2. Ensure that the boiler is set to auto. If you’ve set the timer function to “On” or “Off”, you’ll have to switch it on and off manually.
  3. Set on and off times. You can do this by pressing the pins that surround the boiler timer dial; each pin typically represents a period of 15 minutes.

Bear in mind that this procedure, as well as the configuration of the timer pins, may vary depending on the boiler timer model (but not by much).

How to Set a Digital Boiler Timer

Fundamentally, setting the timer on a boiler is similar whether you have a digital or analogue timer. Of course, there’s no boiler timer dial, so you’ll have to makes your inputs from the display screen. Also, instead of fumbling around with those tiny pins, you’ll have to find a setting called “Set Clock” or “Set Time” before inputting the actual time.

But in a nutshell, here’s what you do:

  1. Make sure the time is correct
  2. Set the timer to “Auto”
  3. Enter the on/off time

Then, to activate the programme, you’ll have to push a button that may be labelled as “Start” or “Set” — again, please refer to the boiler timer manual for instructions specific to your model.

What to Do If Your Boiler Timer Still Isn’t Working

Call a professional to come and help you fix the problem. If your boiler isn’t over 10 years old, replacing the timer will probably be the most cost effective option. There are a tonne of heating engineers that can help you here.

Or, if you expect to get a new timer and have an old boiler, it might be worth considering a boiler replacement. You can get fixed-price quotes from Heatable by filling in their anonymous property questionnaire.

Worcester Bosch Greenstar 4000

Whoever you use, make sure they complete a full diagnostic first. It’s not good replacing the boiler timer, and even the thermostat, to find that neither of the installations fix the problem!

Boiler Timer Not Working: Parting Words

Is there anything we’ve missed?

Have you had an experience with a faulty boiler timer that you’d like to share? If you do or have a question, please leave a comment below!

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  1. Tracy jameson says:

    Is it dangerous if the timer is burnt when changed on boiler after it broke down? It is Burnt on pins and up the side both yellow marks and black scorching marks?

    I’ve lost all trust after faulty boiler repairs today and I was lucky to have someone sort eventually but I need to know were we I. Danger as I’ve been told due to faulty clock as well as main board? I’m in rented and have paid out of my own pocket to get correct repairs done after shoddy agents repair man.

    1. heatingforce says:

      Do you have a picture? I know engineers throughout the UK I could recommend if you’re having trouble finding a reliable one.

  2. Amanda Labrianidis says:

    Hi my timer contoler has just stoped altogether. Even when i push all buttons nothing happens

    1. Alex Ion says:

      Time controller on the boiler or the thermostat?

  3. Rachel Bradley says:

    Hi I’ve just had a new boiler clock and the heating is still not going off when programmed too. The hot water does. The heating comes on as set , but I have to turn the power off to the clock to get the heating to actually turn off. What could it be please?

    1. Alex Ion says:

      It may be that the clock and the boiler don’t communicate as they should. It’s a bit weird to shut off the water but not the heating. I’d have the person who installed it make a visit and see what’s going on.

  4. Phil Smith says:

    I have a wireless timer for a Worcester boiler. Now we are here all day, I have set it to come on 3times a day. The problem is, it comes on at midnight, for 5hours. I don’t want this, and have not timed this. The last timing is 5pm to 7pm. Any idea?

    1. Alex Ion says:

      Check timezone maybe?

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