Eurotronic
Heating Stuck On
Radiator or floor heating stays hot even when thermostat is set to OFF or a low temperature.
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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
Relay contacts welded closed, Miswired thermostat (connected to permanent live), Stuck open thermal actuator or valve, Incorrect parameter settings (valve type NC/NO set wrong)
How to Fix / Troubleshooting
Safety: Isolate mains power before inspecting wiring or valves. Hot water and surfaces can cause burns.
- Check display: Confirm that the thermostat is not calling for heat (no flame icon). If it is, adjust setpoint or schedule.
- Verify wiring: Ensure the thermostat output is wired through the correct relay contacts (COM and NO for normally open). If wired to NC, the system may heat when it should be off.
- Check valve type setting: In the thermostat menu, verify that the valve type (NC = normally closed, NO = normally open) matches the installed Eurotronic actuator.
- Test actuator: Disconnect power to the actuator. If heating stops after it cools, the actuator may be stuck open and should be replaced.
- Replace thermostat/relay: If heating continues even with thermostat removed or relay disconnected, the relay contacts may be welded. Replace the thermostat or relay module.
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Repair Difficulty
Hard
4/5
Required Part
Output Relay / Thermal Actuator
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