BoilerBuddy · homeowner guide
Boiler not turning on: what should I check?
A boiler with no visible response is not the same as one that starts and then fails to ignite. Begin with external controls and whether the display is on; do not infer an internal electrical or gas fault from silence alone.
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 user control, timer or thermostat may not be requesting heat at that moment.
A wider power interruption or an external supply switch may explain a blank display.
A boiler fault can also leave the appliance unresponsive and requires professional assessment.
Safe observations
Checks you can make without opening the boiler
- 1
Check the normal thermostat, programmer or app and confirm the intended heating or hot-water schedule is active.
- 2
Notice whether other household lights or appliances have power. Look at the boiler display and any external indicator without touching wet or damaged equipment.
- 3
Record whether the boiler is completely blank or shows a message. If it has power but does not start, see the ignition guide.
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 remove covers, open the consumer unit to experiment, touch exposed wiring, or work on internal electrical, gas, burner or flue parts. Stop if equipment is wet, damaged or smells burnt.
When to contact a Gas Safe engineer
Contact a Gas Safe engineer if external controls appear correct but the boiler remains unresponsive or shows a fault message. For a household breaker or power-supply issue that recurs, do not keep resetting it; contact a qualified electrician.
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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.