Immergas
Heating Running Continuously / Control Fault
Radiators get hot even when the room thermostat is not calling for heat
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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
Stuck heating relay on PCB, Room thermostat wired incorrectly (permanent call), Motorized valve stuck open
How to Fix / Troubleshooting
Safety: Turn off power before inspecting wiring or valves.
Steps:
- 1. Check thermostat: Confirm that the thermostat is set low or to OFF and that its display is working correctly.
- 2. Observe boiler display: If the boiler shows a constant heat demand symbol even with thermostat off, the control circuit may be shorted.
- 3. Inspect thermostat wiring: At the boiler, ensure that the thermostat wires are not permanently bridged.
- 4. Technician tasks: Test the PCB heating relay and replace the board if stuck. Check any external zone valves for correct operation.
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Repair Difficulty
Hard
4/5
Required Part
Main Control PCB
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