Boiler shuts down with flue or combustion safety fault; signs of poor combustion, possible smell of fumes near boiler.
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
Critical safety: If you suspect flue blockage or fumes, turn off the boiler immediately, ventilate the area, and do not use the appliance until checked by a professional.
User actions:
- Visually inspect the external flue terminal from ground level for obvious obstructions; do not climb or dismantle flue sections yourself.
Engineer actions:
- Check the full length of the flue system for obstructions, corrosion, or dislodged joints.
- Inspect and clean any internal baffles within the Grant boiler’s heat exchanger.
- Verify flue installation complies with Grant’s flueing instructions and local regulations; rectify any non-compliance.
Flue work must be carried out by a suitably qualified engineer due to carbon monoxide risk.