The Trane SEN1001 Watertight Thermistor is a temperature-sensing device designed for accurate monitoring in HVAC systems. It works by changing electrical resistance in response to temperature variations, allowing the control system to adjust operation accordingly. Its watertight construction ensures reliable performance in moist or wet environments. Commonly used in chillers, air handlers, and hydronic systems, it supports precise temperature control. Its use enhances system efficiency, improves reliability, and ensures consistent performance in demanding HVAC applications.