This type of system uses an air-to-air heat pump as the primary heat source and a fossil fuel forced hot air furnace, either oil, natural gas or propane fired as back up heat. Oil or gas furnaces now come with an electronic commutated motor (ECM) which is much more efficient that a regular motor. This motor drives the blower fan which uses less energy that a 100 watt light bulb. Oil furnaces use a state of the art Riello oil burner with AFUE ratings of 87%. The gas furnaces are condensing and have AFUE ratings of 95% and come in 1, 2 and 3 stages of heat. Some models are fully modulating. The heat pump also has 2-stages of heat and comes in 15, 16 or 20 SEER rating.