Smell gas?
Leave the property and call the National Gas Emergency Service on 0800 111 999, free, 24 hours.
These checks are all on the outside of the boiler. Never take the boiler's cover off: only a Gas Safe registered engineer may work inside it. Your boiler's manual is the best guide for your model.
1. Is there power and gas?
Check the boiler's display or lights are on and its fused switch is on. If you have a prepayment gas meter, check it has credit. If your gas hob works, gas is reaching the house.
2. Check the pressure
Most combi boilers have a pressure gauge on the front. Many need it between about 1 and 1.5 bar when the heating is cold; your manual gives the right figure. If it's low, the manual explains how to top it up using the filling loop. If it keeps dropping, there may be a leak: call an engineer.
3. Thermostat, timer and settings
Make sure the thermostat is set above the room temperature, the timer or programmer is calling for heat, and any batteries in a wireless thermostat aren't flat.
4. In freezing weather, check the condensate pipe
Condensing boilers have a plastic pipe that runs outside to a drain. If it freezes, the boiler shuts down. Pouring warm (not boiling) water along the outside section can thaw it. Only do this where you can reach safely from the ground.
5. Reset once
If the display shows a fault code, look it up in the manual. Most boilers have a reset button. Try it once; if the fault comes back, stop and call an engineer.
When to call straight away
Call a Gas Safe registered engineer if you see water leaking from the boiler, it makes banging noises, the pilot light won't stay lit, or none of the checks above help. If you smell gas or have symptoms such as headaches or dizziness near an appliance, leave the property and call 0800 111 999.