What to Do When Your Boiler Breaks Down

Most boiler lockouts can be resolved by the homeowner before calling an engineer. Here's a systematic approach to diagnosing the problem.

Step 1: Check the obvious things

• Thermostat batteries — dead batteries are a very common cause. Replace them first.
• Thermostat setting — make sure it's set above the current room temperature
• Boiler pressure — check the pressure gauge. If below 1 bar, re-pressurise first
• Gas supply — check other gas appliances (cooker, gas fire) still work. If not, call National Gas Emergency 0800 111 999 immediately.

Step 2: Check for an error code

Most modern boilers display an error code when they lock out. Look up your boiler brand and model online — common codes are documented. Many error codes indicate simple resets rather than actual faults.

Step 3: Try a reset

If the boiler has locked out and pressure is correct: press and hold the reset button (usually labelled, often with a flame icon) for 3 seconds. Allow 2–3 minutes for the boiler to restart. If it locks out again quickly, call an engineer.

Step 4: Check the condensate pipe

In freezing weather, the condensate pipe (plastic pipe from boiler to outside drain) can freeze. Gently pour warm (not boiling) water over the outside section of the pipe. Then reset the boiler.

When to call us

If the boiler won't reset after two attempts, shows a persistent fault code, or you smell gas — call us. Don't repeatedly reset a genuinely faulty boiler. Contact Corby Boiler Installations for same-day emergency repairs.