Boiler not firing up? Work through these checks first

A boiler that will not fire up is alarming, especially in winter, but the cause is often something simple you can check yourself before calling anyone out.

Run through the basics

• Pressure. Check the gauge. Below 1.0 bar and the boiler will not fire for safety. Top it up, our pressure guide shows how.
• Power. Check the boiler has power and that a fuse or switch has not tripped.
• Gas. Is your gas supply on? Check another gas appliance, like a hob, is working.
• Thermostat and timer. Make sure the heating is actually programmed to be on and the thermostat is turned up.
• Fault code. Note any code on the display. Manufacturer sites like Worcester Bosch and Ideal explain what each code means.

Frozen condensate pipe (a winter classic)

If it is cold out and your boiler suddenly stops with a fault, a frozen condensate pipe is a common culprit. This is the white plastic pipe running outside. Gently warming it with a warm cloth or a hot water bottle often thaws it, then reset the boiler.

Try a reset

Most boilers have a reset. Hold it for a few seconds. If the boiler fires and stays on, you are sorted. If it keeps locking out, stop and call a professional.

When to call an engineer

If the basics check out and the boiler still will not fire, it is an engineer job. If the boiler is old and this is one of many problems, it may be time to read our signs you need a new boiler guide. Either way, tell us what is happening.