Fan Fault
Grant
Combustion Fan or Air Pressure Switch Failure
Boiler indicates a fan or air pressure fault; fan does not start or starts then stops, boiler locks out.
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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.
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Possible Causes
Failed fan motor, Blocked flue or air intake, Faulty air pressure switch, Loose or damaged fan wiring harness
How to Fix / Troubleshooting
Safety: Isolate electrical supply before removing the boiler casing. Flue work must comply with regulations.
User checks:
- Visually inspect the flue terminal outside for obstructions such as leaves, nests, or snow; clear any blockage.
- Ensure any air intake grilles are not covered.
Engineer checks:
- Test the fan motor for correct voltage supply and rotation; replace the fan assembly if seized or noisy.
- Inspect and clean the air pressure switch tubes and flue connection points for condensate or debris.
- Check the air pressure switch contacts for correct operation under fan pressure; replace if it fails to close or open as required.
- Verify integrity of the wiring harness between the fan, pressure switch, and main PCB.
Do not run the boiler with a known fan or flue fault; this can lead to dangerous combustion conditions.
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Repair Difficulty
Hard
4/5
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