F3
Ideal
Fan or Air Pressure Switch Fault
Unit attempts to start, then shuts down with F3, fan may run briefly.
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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
Blocked flue or air intake, Faulty fan motor, Stuck or failed air pressure switch, Split or disconnected pressure tubing
How to Fix / Troubleshooting
Safety: Switch off power and isolate gas. Do not operate the heater with the case removed.
- Check flue terminal: Outside, inspect the flue terminal for obstructions such as leaves, plastic bags, or insect nests. Clear any blockage without inserting tools deep into the terminal.
- Inspect air intake (if concentric or twin-pipe): Ensure the air intake is not blocked or restricted.
- Check pressure tubes: With the cover removed, locate the air pressure switch and its silicone tubes. Make sure the tubes are not kinked, split, or disconnected. Refit securely.
- Listen to fan: On restart, listen for the fan. If it does not run or is noisy/grinding, the fan assembly may be failing.
- Do not bypass safety devices: Never bridge the air pressure switch. If F3 remains after basic checks, contact a qualified engineer to test the fan and pressure switch electrically.
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Repair Difficulty
Hard
4/5
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