The Triangle Tube PARKIT165 Outdoor Sensor Kit is a temperature-sensing accessory designed for compatible Triangle Tube boiler systems. Installed outdoors, the sensor monitors ambient temperature and communicates this information to the boiler control, allowing the heating system to automatically adjust water temperature based on outdoor conditions. Used with Triangle Tube Prestige an... https://www.partshnc.com/triangle-tube-parkit165-outdoor-sensor-kit