A18
Riello
Unstable Flame / Intermittent Flame Failure
Boiler indicates flame loss during operation, cycles on and off with lockouts
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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
Fluctuating gas or oil pressure, Partially blocked burner nozzle (oil) or injector (gas), Dirty burner head or combustion chamber, Faulty flame sensor
How to Fix / Troubleshooting
Safety: Combustion adjustments and nozzle changes must be done by a qualified engineer.
- Check fuel supply stability: For oil, ensure the tank is not nearly empty and that filters are clean. For gas, check if other gas appliances are affected.
- Inspect burner (visual): Through the sight glass, look for signs of sooting or unstable flame. Do not remove covers while running.
- Reset once: Reset the boiler and observe. Repeated flame loss indicates a deeper issue.
- Professional service: A technician should clean the burner head, replace the oil nozzle or check gas injectors, verify pressures, and test the ionisation electrode.
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Repair Difficulty
Professional Required
5/5
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