E18
Comenda
Boiler Overtemperature / Safety Trip
Boiler overtemperature; machine locks out heating and displays E18.
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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
Failed boiler thermostat, Stuck boiler contactor, Scale buildup reducing heat transfer, Faulty control board
How to Fix / Troubleshooting
Safety first: Disconnect power and allow boiler to cool completely. Boiler components can be under pressure and very hot.
- Reset safety thermostat: Press the manual reset on the boiler safety thermostat if present. If it trips again, investigate cause.
- Descale boiler: Heavy scale can cause localized overheating. Follow Comenda’s descaling procedure or have a technician descale the boiler.
- Check contactor: Ensure the boiler contactor opens when heating is not requested. Replace if welded closed.
- Verify control settings: Confirm that boiler temperature setpoint is within recommended range.
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Repair Difficulty
Professional Required
5/5
Required Part
Boiler Safety Thermostat
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