What is this?
An electric radiator that will not turn off is running continuously regardless of the thermostat setting or room temperature. This wastes energy, can overheat the room, and may indicate a fault that could become a safety issue if left unchecked.
Common causes
- Thermostat has failed in the closed (on) position
- Relay or contactor stuck in the on position
- Electronic control board fault keeping the element energised
- Wiring error bypassing the thermostat
- Faulty room sensor giving a false low-temperature reading
Is it dangerous?
A radiator that will not turn off is a moderate concern. While most radiators have a thermal safety cutout to prevent overheating, continuous running wastes energy and puts unnecessary strain on the element. In a room with poor ventilation, it could also cause the room to become uncomfortably or dangerously hot.
Can I fix it myself?
Turn the thermostat to the lowest setting or to the off position. If the radiator continues to run, the thermostat has likely failed. For plug-in models, unplug it. For hardwired models, switch off the isolator or fused spur until an electrician can attend.
When to call an electrician
Call an electrician if the radiator does not respond to the thermostat or controls, if switching it off requires isolating the circuit, or if the radiator is getting excessively hot. This is not an emergency but should be addressed promptly.
What will an electrician do?
Test the thermostat to confirm it has failed
Check the relay or contactor for sticking
Test the electronic control board
Replace the faulty thermostat, relay, or control board
Test the repaired unit to confirm it cycles correctly
Typical cost
£80 – £200
Thermostat and relay replacements are straightforward. Control board replacements depend on the model and parts availability.
