Forced air systems provide heating and air conditioning to a home using a system of ducts with air as the transfer medium. These systems have a blower that pulls air from the living space through the conditioning system and forces it through ducts for distribution throughout the home.
Forced air heating systems use a variety of fuel types to provide heating. Some systems burn natural gas, propane or heating oil, whereas others use electric resistance coils or heat pumps to provide heat.
Because the system circulates the volume of air from the home through the unit several times each day, it is possible to add air filters and humidifiers or dehumidifiers to the unit. These devices help improve air quality and comfort in the home.
The blower gives the forced air system the ability to provide air conditioning as well. Early ducted-heating systems used gravity to distribute heat to the various rooms of the home. Because hot air is less dense than cold air, by placing the furnace in the basement or other area under the floor, the warm air rises naturally through the ducts and the cold air drops back to the furnace for heating. However, gravity systems are inadequate for providing air conditioning for the home.