F06
Ferroli Boiler Not Detected / No Response on BUS

Thermostat shows F06 and cannot detect the boiler; heating and DHW control are disabled.

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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

Boiler not powered or in standby mode, BUS cable disconnected from boiler, Incompatible boiler type selected in thermostat configuration, Faulty BUS interface on boiler main PCB

How to Fix / Troubleshooting

Safety first: Work only on external controls and low‑voltage wiring. Do not open the boiler casing.

  • Verify boiler power:
    • Check that the boiler display is on and not in a deep standby mode.
    • Ensure the boiler's main switch is set to ON and that there are no boiler error codes.
  • Check BUS connection:
    • Isolate power to boiler and receiver.
    • Confirm the BUS/OpenTherm cable is connected to the correct terminals on the boiler and receiver.
  • Check boiler type setting:
    • In the thermostat installer menu, verify that the correct Ferroli boiler model or protocol is selected.
  • Test with simple on/off (if supported):
    • As a diagnostic, switch the thermostat to on/off relay mode (if allowed) and wire it to the boiler's room thermostat contacts.
    • If the boiler responds in on/off mode, the BUS interface may be faulty.
  • Contact service if unresolved:
    • A technician may need to test or replace the boiler main PCB BUS interface.
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Repair Difficulty

Hard 4/5

Required Part

Ferroli Boiler Main PCB (BUS Interface)
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