Lochinvar & A.O. Smith 100274734 Flue Sensor 323613-751 Flashing LEDs on the left

Flashing LEDs on the left side of the 3-digit display indicate an active alarm condition

or when 24 VAC is confirmed at the terminals but no gas flow is detected at the burner

preserving the UL listing and safety certifications of the original equipment

The internal switches are rated for 2 HP at 120V AC

Durable Construction: Heavy-duty components designed to handle the thermal stress of HVAC combustion cycles

Lochinvar & A.O. Smith 100274734 Flue Sensor 323613-751 Flashing LEDs on the leftThe Lochinvar & A. O. Smith 100274734 Flue Sensor is a critical safety component designed for high efficiency condensing boilers and water heaters. This exhaust temperature sensor monitors the heat levels within the venting system to prevent heat exchanger damage and plastic vent meltdown. Also identified by part number TST2013, this NTC thermistor provides the control board with precise resistance readings, ensuring the unit modulates or shuts down