Ferroli No Central Heating / Diverter Valve Fault

Boiler provides hot water but central heating does not work, with no error code.

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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

Diverter valve stuck in DHW position, Faulty motorised head on diverter, Faulty room thermostat or wiring, PCB not sending CH demand

How to Fix / Troubleshooting

Safety first: Turn off power before accessing the boiler internals.

  • Check controls: Ensure the room thermostat is set high enough and the programmer is calling for heat.
  • Radiator valves: Confirm that radiator valves are open.
  • Engineer checks:
    • Test the diverter valve motor and mechanism; replace if stuck or failed.
    • Verify CH demand signal at the boiler terminals.
    • Check PCB outputs to the diverter valve.
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Repair Difficulty

Hard 4/5

Required Part

Diverter Valve Assembly
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