Why Your Boiler Keeps Switching Off

Few things are more frustrating than a boiler that fires up and then shuts down again a minute later. If your boiler keeps switching off, it is trying to protect itself from something, and the trick is working out what. Here are the usual culprits.

Low pressure

This is the most common reason a boiler keeps switching off. If the pressure gauge reads below about 1 bar, the boiler will often cut out. Topping it up may solve it, but if it drops again there is likely a small leak. Our guide on boiler pressure that keeps dropping covers this.

A frozen condensate pipe

In a North East winter this is a classic. A blocked or frozen condensate pipe makes the boiler lock out as a safety measure. See our guide on a frozen condensate pipe for the fix.

Thermostat or air in the system

A faulty thermostat can short cycle the boiler, switching it on and off too often. Trapped air or a sticking pump can do the same by stopping water flowing properly through the system.

Sensors and internal faults

If none of the above apply, the cause may be a faulty sensor, a worn pump or a fault on the control board. These need a Gas Safe engineer rather than a home fix.

If your boiler keeps switching off after you have checked the pressure and tried one reset, do not keep cycling it. Book a boiler repair so the real cause is found before it leaves you with no heat at all.