F28
Protherm
Ignition Lockout / No Flame Establishment
Boiler displays F28, repeated ignition attempts with clicking but no flame
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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
No gas supply or air in gas line, Blocked burner or injector, Faulty ignition electrode or cable, Defective gas valve or low inlet pressure
How to Fix / Troubleshooting
Safety: Gas work must be performed by a licensed technician. Do not repeatedly reset the boiler if F28 persists.
User checks:
- Confirm that other gas appliances in the property work to rule out a general gas supply issue.
- Ensure the boiler’s gas isolation valve is open.
Technician checks:
- Bleed air from the gas line if the supply has recently been interrupted.
- Inspect and clean the burner and injectors for debris or corrosion.
- Check the ignition electrode gap and position; replace if worn or cracked.
- Measure gas inlet pressure and operating pressure; adjust or replace the gas valve if outside Protherm specifications.
After repair: Perform combustion analysis and verify reliable ignition without F28.
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Repair Difficulty
Professional Required
5/5
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