Service Type: Boiler & Thermostat Check Equipment: Navien NCB-H Combi Boiler, Fan Coil Air Handler, Basic Thermostat, Outdoor Temperature Sensor Client Concern Client noted indoor temperature reaching 20–20.5 °C when setpoint was 19.5 °C. Inspection & Findings Checked all system settings and parameters; boiler and air handler operating normally. Slight overshoot may be due to outdoor reset curve or coil heat lag. Thermostat batteries were low; replacing batteries could help improve accuracy. Recommendations Monitor system after battery replacement. If temperature consistently rises >1.5 °C above setpoint while boiler/fan continue running, thermostat contact may be stuck and thermostat replacement recommended. Status: System operating normally; no other issues observed.