BoilerBuddy · homeowner guide
Boiler not igniting: what can I check safely?
This guide is for a boiler that appears to respond to a heat demand but does not provide heat. It is different from a boiler with no display or other signs of power. Sounds and screen messages are clues, not proof of an ignition fault.
Similar symptoms can have different explanations. The possibilities below are not a diagnosis.
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Understand the symptom
What might be behind it?
The boiler may not be receiving the expected demand from its user controls or timer.
A supply interruption or a condition detected by the boiler may prevent it from starting.
An internal appliance fault is possible and needs diagnosis by a qualified engineer.
Safe observations
Checks you can make without opening the boiler
- 1
Check that the normal room control or hot-water control is set to request heat, following its user instructions.
- 2
Observe whether the screen lights, whether the boiler makes a sound, and whether any code appears. Do not remove a cover to look for a flame.
- 3
Write down what happens and when. Do not keep pressing reset; use a reset only if the exact user manual instructs you and there are no warning signs.
Know when to stop
Stop if you notice
- A smell of gas, or a yellow, orange or sooty flame.
- A carbon monoxide alarm is sounding, or someone has possible CO symptoms.
- Smoke, scorching, visible damage, overheating or a leak around the boiler.
- The boiler keeps locking out or will not stay lit.
What not to touch
Do not open the casing, inspect the burner, electrodes, gas valve or flue, adjust gas controls, test gas pressure, or bypass a safety device. Do not repeatedly reset a failed start.
When to contact a Gas Safe engineer
Contact a Gas Safe engineer when the boiler fails to start, locks out, or the problem returns after a manual-approved user action. Record the code and identify the model if possible.
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Get help that matches what you can see
If you do not know the fault code or exact model, start with the symptom check. Record any displayed code from the screen without opening the boiler casing.
Official safety sources
HSE guidance says not to use an appliance you suspect is unsafe and that domestic gas work must be carried out by a Gas Safe registered engineer. Follow the emergency guidance if you suspect a gas leak or carbon monoxide exposure.
Need a qualified engineer?
BoilerBuddy can pass what you've worked out to a local Gas Safe engineer — symptoms, checks, and the bits that point to the likely cause.
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Engineer handover
Send this sheet with you to the visit.
Print or email it to your engineer so they arrive already knowing what your boiler is doing and what you've already tried.