Boiler runs continuously even when the thermostat setpoint is reached; rooms overheat.

Safety first: Overheating can damage the system. Be prepared to switch off the boiler at the main switch if necessary.

• Check thermostat display:
  • Confirm whether the thermostat indicates an active heat demand icon when setpoint is below room temperature.
• Inspect wiring:
  • Ensure there is no permanent link across the boiler's room thermostat terminals in addition to the Ferroli receiver.
• Test relay:
  • With power off, disconnect one wire from the receiver's switched output.
  • Restore power; if the boiler stops running, the relay or control wiring was holding it on.
• Replace faulty receiver:
  • If the relay is welded closed, install a new Ferroli smart thermostat receiver.