In a straight heat pump or supplementary electric heater application, at least one outdoor thermostat is required to cycle the heaters as the outdoor temperature drops. In the Fuelmaster system, the indoor thermostat controls the supplemental heat source (furnace). The outdoor thermostat is not required. Since the furnace is serving as the secondary heat source, the Fuelmaster system does not require the home rewiring usually associated with supplemental electric strip heating.
