E13 appears and the thermostat refuses to start heating due to an over-temperature safety condition.

Safety first: If any surface feels excessively hot or there is a burning smell, switch off the heating system immediately at the main switch and investigate before resetting.

• Check actual temperature: Use an independent thermometer to verify room or floor temperature. If genuinely too high, reduce setpoint and allow the system to cool.
• Inspect installation location: Ensure the thermostat is not mounted above a radiator, fireplace, or in direct sunlight. Relocate if necessary.
• Review safety limits: In the installation menu, check the maximum floor or room temperature limit. Ensure it is set according to Delta Dore and floor manufacturer recommendations (often 28–32°C for floors).
• Reset fault: After cooling, clear E13 by power cycling the thermostat or using the reset option in the menu. Monitor operation closely.

If E13 recurs with normal temperatures, the high-limit sensor or associated circuitry may be faulty and should be checked by a professional.