A furnace uses fuel (gas, propane, etc.) to generate flame, which heats up the heat exchanger. Air blows over the heat exchanger and warm air is then supplied to the home. In the summer, the furnace simply acts as a blower, returning warm air and then supplying cold air from the evaporator coils. A heat pump uses refrigerant to both heat and cool the home. A device called a reversing valve changes the direction of the refrigerant, and in the summer it produces cold air, then in the winter it runs in reverse, producing warm air. 

WHAT ARE THE BENEFITS OF USING A HEAT PUMP?