Display shows A10; Ferroli furnace may not respond to thermostat or may behave erratically.

Safety: Isolate power before working on control wiring.

Steps:

• Check thermostat settings: Ensure the room thermostat or Ferroli controller is calling for heat and not in OFF or holiday mode.
• Inspect wiring: At the furnace terminal strip, verify that thermostat wires are securely connected and not damaged. Tighten loose screws.
• Bypass test (qualified persons only): Temporarily link the room thermostat terminals at the furnace to simulate a call for heat. If the unit runs normally, the external thermostat or its wiring is faulty.
• Reset controls: Power-cycle the furnace and any Ferroli-branded controller to clear communication glitches.

Professional help: Complex control systems (e.g., OpenTherm, modulating controls) should be diagnosed by a technician familiar with Ferroli control protocols.