What to Do When Your Boiler Stops Working

When your boiler stops working, you lose heating and hot water, and that is a real problem in winter. Before you call an engineer there are some safe checks you can try that sometimes get things running again. This guide explains what to check, what to leave alone and when to get professional help.

Safety first: gas and carbon monoxide

Safe checks you can try

1. Check the power and gas supply

   Make sure the boiler is switched on and has power. Check that a fuse or circuit breaker has not tripped. Check your other gas appliances, such as the hob, or your gas meter, in case the supply has run out or is interrupted. If you have a prepayment meter, check it has credit.

2. Check the thermostat and programmer

   Check the thermostat is set high enough, the programmer or timer is set correctly and the batteries in any wireless thermostat are not flat. A simple setting error is a surprisingly common cause.

3. Check the boiler pressure

   Look at the pressure gauge on the boiler. Most combi boilers should read around 1 to 2 bar when cold, but check your manual. If the pressure is low, you may be able to top it up using the filling loop by following the manufacturer's instructions. If it keeps dropping, there may be a leak and you should call an engineer.

4. Look at the display or error code

   Many boilers show a fault code. Look it up in your manual or on the manufacturer's website. If the manual allows a reset, press the reset button once. If the fault returns, do not keep resetting it.

5. Check the condensate pipe in freezing weather

   In cold weather the condensate pipe, the plastic pipe that carries waste water from a condensing boiler outside, can freeze and shut the boiler down. Pouring warm (not boiling) water over the pipe can unfreeze it. If you are not comfortable doing this, ask an engineer.

6. Check for cold spots in radiators

   If the boiler works but the radiators are cold at the top, they may need bleeding to release trapped air. If they are cold at the bottom, there may be sludge in the system, which needs professional attention.

Common reasons a boiler stops working

What not to do

When to call an engineer

Call a qualified engineer if the checks above do not get the boiler working, if it keeps losing pressure, if you can see water leaking from it, if it makes unusual noises or if it keeps shutting down. If it is very cold and you have no heating or hot water, treat it as urgent, particularly if anyone vulnerable lives with you. Our team covers heating and gas work 24/7, and you can check our rates before you call. Not sure whether to call out of hours? See the 7 signs you need an emergency plumber.

Frequently asked questions