Lochinvar & A.O. Smith 100274734 Flue Sensor 321894 709 This HVAC replacement part is This HVAC replacement part is critical for restoring cooling capacity and maintaining system superheat within manufacturer tolerances Use a 1 2" minimum bend radius and ensure the bulb is securely mounted in the path of the medium being measured for the most accurate thermal response the 100274734 sensor is designed to monitor exhaust gases regardless of the fuel type used in the combustion process Integrating this condensing boiler sensor during routine maintenance helps maintain peak thermal efficiency and protects the secondary heat exchanger from excessive thermal stress