Smart thermostat shows F.20 and indicates an internal temperature overheat or hardware protection event.

Safety: Avoid touching very hot surfaces; otherwise low risk.

• 1. Check mounting location: Ensure the thermostat is not directly above a radiator, on a chimney breast, or in direct sunlight. If it is, plan to relocate it to an interior wall away from heat sources.
• 2. Improve ventilation: Do not cover the thermostat with furniture, curtains, or decorative covers. Ensure air can circulate freely.
• 3. Monitor temperature: After relocating or improving airflow, monitor whether F.20 reoccurs during normal operation.
• 4. Internal fault: If F.20 appears even in a cool, shaded location, the internal temperature sensor or power components may be overheating. Replace the thermostat.