Display shows F18, heater may shut down during operation, sometimes with fan still running.

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

Failed fan speed sensor, Fan motor wear, Blocked fan impeller, Faulty fan control circuit on PCB

Safety: Turn off power and gas. Do not run the heater with the case removed.

Inspect fan area: Remove the front cover and visually check the fan housing for debris or signs of water ingress.
Check fan connector: Ensure the multi-pin plug to the fan is fully seated and not corroded.
Spin test: Gently rotate the fan impeller by hand (when cold and power off). It should turn freely without grinding.
Professional testing: If F18 persists, a technician should test fan speed feedback and replace the fan assembly if necessary.

Hard 4/5

Flue Fan Assembly

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