Abstract: A heating system for supplementing a conventional furnace or the like is disclosed. The system includes a blower that receives air from the hot air supply system of the conventional furnace, and directs the air through a separate duct to the space to be heated. The present heating system may include solar collectors using air as the heat transfer fluid so that the heat transfer fluid can be directed into the space to be heated. The system also includes one or more low-wattage electric heating elements arranged so that one element is energized when the temperature is slightly below the desired temperature, and additional elements are energized as the temperature falls lower, to maintain the least possible electric energy usage.