A whole-house fan is a type of fan, or exhaust system commonly venting into a building's attic, designed to circulate air in a home or building. It is sometimes confused with a powered attic ventilator, which exhausts hot air from the attic to the outside through an opening in the roof or gable at a low velocity.
A whole-house fan pulls air out of a building and forces it into the attic space. This causes a positive pressure differential in the attic forcing air out through the gable and/or soffit vents, while at the same time producing a negative pressure differential inside the living areas which draws air in through open windows.
Powered attic ventilators, by comparison, only serve to remove some hot air from the attic. Intake air comes directly from outside, instead of from the house interior. This system is used when air intake from the house is not desirable, such as when the interior is air-conditioned.
Whole-house fans were mainly popularized in the Southern United States through the 1950s-60s, as they were much cheaper and easier to find than air conditioners and still removed hot and stale air relatively well.
There are two types of fan:
- Ceiling Mounted: Mounted on ceiling between the attic and living space.
- Ducted: Remotely mounted away from the ceiling; can exhaust heat from multiple locations; operation is extremely quiet.
- Whole House Fan Defined, "http://www.homewyse.com/definitions/whole_house_fan.html"
- Attic Ventilator Defined, "http://encyclopedia2.thefreedictionary.com/attic+ventilator"