Boiler attempts to start, fan runs, ignition clicks heard, then shuts down with a flame failure indication on the control panel.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety: Isolate power and allow the boiler to cool before removing any combustion covers. Only a competent person should work on combustion components.
User checks:
- Ensure all air vents and flue terminals around the Grant boiler are unobstructed (no leaves, plastic bags, or debris).
- Check that any room or cupboard ventilation grilles are not blocked.
Engineer checks:
- Remove and clean the photocell with a soft cloth; check its wiring back to the burner control box.
- Inspect the burner head, blast tube, and baffles for heavy soot or carbon build-up; clean and reassemble as per Grant instructions.
- Verify correct air shutter setting on the Grant burner and adjust using a flue gas analyser to achieve correct CO₂/O₂ values.
- Test the burner control box for correct sequence; replace if it fails to energise the solenoid valve or misreads the photocell.
Do not repeatedly reset a boiler with flame failure; unresolved issues can lead to unsafe combustion. Engage a Grant-approved technician if unsure.