Manufacturer Part Number: OT18-60A

This is an outdoor temperature sensor that is used when a heat pump and gas furnace are paired together as heating equipment for the home. This outdoor sensor is designed to work in addition to the Fossil Fuel Kit, AFE18-60. The two devices together will automatically discontinue the use of the heat pump when outdoor temperatures are about 40 degrees or less, and then use the gas furnace for heat instead.