Boiler troubleshooting

There could be any number of reasons why your boiler has stopped working, but thankfully there are a few that you can easily fix yourself. Whether it’s checking the pressure, thawing a pipe or relighting your pilot light – these tips are all you need for troubleshooting boiler issues.

Condensate pipe

This is a very common reason boilers stop functioning in the winter and is thankfully a very quick fix. Even the most well looked-after boiler will struggle to function if its condensate pipe freezes or becomes blocked. It’s the pipe that carries condensation from your boiler to your outside drain and you probably didn’t even know what it was for until now.

It’s prone to freezing in bouts of cold weather, and your boiler will stop working if it does. If you can’t see where it’s frozen, you can identify which part is blocked by running your hand over the pipe to see where it’s coldest. Then, simply pour a kettle-full of hot water over the pipe to thaw it. You can prevent pipes from freezing in future by covering them in pipe insulation.

Check the thermostat and timer

It might sound silly but you’d be surprised at how many times someone assumes their heating is broken, only to find that the heating is not scheduled to be on or the thermostat isn’t high enough. The very simple way to test the thermostat is to turn it all the way up – if you hear a click, that means the heating has ‘clicked on’. You can turn it back down and figure out exactly where the clicks happens – anything above that point will kick your radiators into action.

Checking the timer will depend on your system, but common things you should check is that the time itself is accurate and whether it’s set to Off, On continuously, Once or Twice.

Check the pilot light

Your boiler doesn’t always stay ‘lit’ and the pilot light is a great place to check if you find yourself without heating or hot water. If you have a combi boiler, you should have a small window on the front of your boiler which you can see the pilot light through. If it’s out, you know you’ll need to reset it – you’ll find instructions in your boiler’s manual but it’s often just a simple case of holding down a button.

If your pilot light keeps going out, you could have a problem with the thermocouple (the small copper rod that shuts the gas safety valve). It’s always best to get a Gas Safe registered engineer to sort this.

person changing boiler controls

Check the pressure

The correct pressure for your boiler should be set between 1 and 1.5 bar (but always check your user manual for precise details on your system). If the pressure is below this level the boiler won’t be working efficiently and may actually be dangerous. The unfortunate news (especially during winter time) is that the heating system needs to be off and cold before you make any adjustments.

There should be two blue taps attached to the boiler for the cold water inlet into the system. Turn both taps on a quarter turn. Once the water pressure has reached the correct setting (as referenced in your manual), turn off the water inlet taps off again. Now you can turn the heating on everything should be working again.

Gas Safe reminder

The issues listed above are all things you can safely check yourself, but it’s worth remembering that your boiler uses gas and is very dangerous! You shouldn’t tinker if you don’t know what you’re doing and you should have a carbon monoxide monitor fitted (and kept in batteries) near the boiler. This could potentially save your life, as carbon monoxide has no smell and is invisible. Read our guide on staying Gas Safe.

If you do need to call out an engineer, make sure that they’re Gas Safe registered. They may be more expensive than your local we-fix-all engineers down the road but can you put a price on your family’s safety?