F5
Protherm
Fan / Air Pressure Switch Fault
F5 displayed, appliance attempts to start but shuts down, fan may not run correctly
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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
Defective fan motor, Blocked air intake or flue, Faulty air pressure switch, Split or blocked pressure tubing
How to Fix / Troubleshooting
Safety first: Disconnect power and gas. Allow the unit to cool. Working on the flue and fan involves exposure to sharp metal edges.
- Check flue and air intake: Inspect the concentric flue terminal for obstructions. Ensure the flue pipes are correctly assembled and not crushed or disconnected.
- Inspect fan operation: With the cover removed and power restored briefly, start a demand and observe if the fan runs. If it does not start or is noisy, the fan assembly may be seized or defective.
- Check pressure switch and tubing: Locate the air pressure switch and its silicone tubes. Ensure tubes are not kinked, blocked with condensate, or split. Clean or replace as needed.
- Test pressure switch contacts: Using a multimeter, verify that the pressure switch closes when the fan runs. Replace the switch if it fails to change state.
- Replace fan if needed: If the fan does not reach speed or stalls, replace the complete fan assembly with the correct Protherm part.
Warning: After any flue or fan work, perform a full combustion safety check and verify there are no flue gas leaks.
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Repair Difficulty
Hard
4/5
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