Abstract: A heating system control unit is provided for use with a heating system. The control unit includes a switching element connected to a first temperature switch associated with a first stage heater, a second temperature switch and a second stage heater of the heating system. The switching element is adapted for actuating the second stage heater upon the receipt of the second temperature signal and further continuing the actuation of the second stage heater until the lack of receipt of both the first temperature signal and the second temperature signal. A thermostat on the outdoor coil serves to pass the signal from the second temperature switch only upon a temperature of the outdoor coil being below a predetermined amount of about 25 degrees Fahrenheit.