A furnace heating fan is an integral part of a heating system that moves the heated air through the heating network. Central heating systems are usually forced air systems that require a fan or blower to circulate the heated air.
The warm air in a heating system moves from the furnace through the system's network of ducts to reach all areas of a house or building. However, a fan must provide motive power in order to distribute the heated air throughout all parts of the duct network before the air loses its heat. Furnace fans generally use motors of one horsepower or less.