Furnace shows external thermostat or room sensor error, heating does not respond to room demand correctly

Safety first: Turn off power before working on low-voltage control wiring.

• Check thermostat settings: Ensure the room thermostat or controller is set to heating mode and above room temperature.
• Inspect wiring: At the furnace terminal strip, verify that the thermostat wires are firmly connected and not corroded. Trace the cable for visible damage.
• Bypass test (for simple on/off stats): With power off, temporarily link the thermostat terminals at the furnace. Restore power; if the furnace now responds, the thermostat or its cable is faulty.
• Verify control configuration: In the Roca control menu, confirm that the correct type of external control (on/off, OpenTherm, etc.) is selected.

Warning: Do not leave thermostat terminals permanently bridged; this is only for testing.