Hydro-X Thermostat Station 2 (heat pump and conventional HVAC)TS 2 Thermostat Station is specifically designed to replace the traditional thermostat to control four system types of equipment's (Heat Cool, Cool only, Heat only, Heat pump). It will control your four system equipment by Day Night setpoint base on the photocell status. Connect the TS 2 to where your thermostat is on the wall using preexisting wires, now you can use the TS 2 in conjunction with the Hydro X to control heating & cooling equipment.