E12
Termet
Room Thermostat / Control Communication Fault
Boiler shows E12, no response to thermostat demand, display may indicate communication error.
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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
Broken or shorted thermostat cable, Incorrect wiring to Termet control terminals, Incompatible or faulty room thermostat, Fault in low-voltage control circuit on PCB
How to Fix / Troubleshooting
Safety first: Isolate power before working on control wiring.
User checks:
- Ensure the room thermostat (if external) has power and is set above room temperature.
- Check that any wireless receiver for the thermostat shows a stable link.
- Reset the boiler and thermostat.
Technician checks:
- Verify correct wiring to the Termet boiler control terminals according to the installation manual.
- Bridge the thermostat terminals temporarily to test boiler response; if the boiler starts, the thermostat or wiring is faulty.
- Check continuity of thermostat cable and replace if damaged.
- If wiring and thermostat are correct, test the main PCB control input and replace PCB if necessary.
Use only compatible thermostats approved for the specific Termet model.
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Repair Difficulty
Medium
3/5
Required Part
Room Thermostat (External Control)
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