The furnace runs, but the room temperature overshoots the setpoint significantly.

Safety first: This is primarily a comfort and efficiency issue, not usually a safety fault.

• Relocate thermostat: Place the thermostat in a representative room away from direct sunlight, drafts, and heat sources.
• Lower flow temperature: Reduce the CH flow temperature to allow more gradual heating.
• Enable weather compensation: If an outdoor sensor is installed, configure weather-compensated control to smooth temperature changes.
• Use modulating control: Install a Remeha modulating controller compatible with the furnace to improve temperature stability.