Why is my boiler not firing?

It's important to talk to an expert boiler engineer before taking any action.

The boiler not firing up the heating system could be due to many reasons. It’s highly risky for unqualified people to try to fix boilers especially if they are gas boilers, which by law require a qualified boiler installation engineer.

Your boiler not firing up your central heating might be very easy to fix by switching it off and on again.

Please check the reasons below and see if there is an easy answer as to why your boiler is not firing up:


The boiler not firing might be due to thermostat being set too low. The heating system will not start until its environment temperature is below the level set on the boiler system. Increase the thermostat to a higher level and hopefully this will solve the reason why your boiler is not firing.


Bleeding your radiators will remove pockets of air. The boiler not firing might be because the air trapped in your central heating system prevents your radiator from running efficiently and effectively. Bleeding is the term used for letting air out of a radiator and heating system. Find out here how to bleed your radiators.


If the boiler does not have enough pressure, it will be unable to fire up. Leaks can be very small and you may not be able to see them. Check the water pressure meter, which is usually found on the front of your boiler. For most boilers, this should be set around the 1 bar.

Frozen Pipes

Unprotected or incorrectly installed condensate pipes can freeze in extreme conditions, preventing the boiler from working.


The heating system will only fire up at the precise time you have set the boiler timer to fire up.

Try turning it off and on

This often solves many issues, not just the boiler not firing.

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