F11
Ferroli
Relay Output Fault / Stuck or Burnt Contacts
Thermostat shows F11 and cannot switch the boiler on even though it sends a heat demand.
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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
Overcurrent through thermostat relay contacts, Welded relay contacts stuck open or closed, PCB track damage near relay, Incorrect wiring causing relay overload
How to Fix / Troubleshooting
Safety first: The receiver may contain mains voltage. Isolate power at the breaker before opening.
- Visual inspection:
- Open the receiver housing with power off.
- Look for burn marks around the relay or terminals.
- Check wiring load:
- Confirm that the relay is only switching the boiler control circuit (low current), not pumps or electric heaters.
- Test relay operation:
- With power restored, request heat and listen for a click from the relay.
- If no click or boiler does not respond, the relay may be faulty.
- Replace receiver:
- Install a new Ferroli smart thermostat receiver and wire it identically.
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Repair Difficulty
Hard
4/5
Required Part
Ferroli Smart Thermostat Receiver Relay Board
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