Lochinvar & A.O. Smith 100170487 Upper Sensor 321042-401 Includes the critical low-pressure switch

Includes the critical low-pressure switch to safeguard against fuel supply drops

this rugged unit maintains stable discharge air temperatures in harsh environments

Easy Installation: Standard 2-wire lead terminals and mounting brackets allow for a fast swap during service calls

You can manually override this at the thermostat to reset the sequence

Lochinvar & A.O. Smith 100170487 Upper Sensor 321042-401 Includes the critical low-pressure switchThe Lochinvar & A. O. Smith 100170487 Upper Sensor (formerly TST1187) is a critical thermistor based component engineered for high precision temperature monitoring in residential and commercial water heaters. As a direct immersion NTC temperature sensor, it provides real time resistance feedback to the control board, ensuring the appliance maintains optimal setpoints while preventing dangerous high limit conditions. This OEM water heater sensor is