A blower fan is a powerful electric machine that provides ventilation or air circulation for appliances or buildings that need air flow. A blower fan might be as small as the matchbook-size device in a laptop used to keep the processor cool or as large as a truck, installed in a large factory to provide ventilation. Technically, a fan is a device that provides 1,136-2,066 millimeters of water gauge (mmWG) pressure — more than a simple fan and less than a powerful air compressor. This type of fan has three main components: the fan, by which air is moved through its blades; a powerful motor with lubricated moving parts that spin the fan blades; and a power supply that provides electrical power to the motor. A metal or plastic housing contains the assembled parts.
Very common as exhaust fans in industrial and commercial buildings, blower fans have become more prevalent in residences. More and more frequently, home builders and home owners have looked to conserve energy, making homes as airtight as possible. Homeowners insulate walls and attics, seal cracks and holes, wrap their homes in house wrap and install weather-tight doors and windows to conserve energy and prevent expensive loss of heat or cooling air. These energy-saving tactics, however, greatly reduce home air quality. Thus, blower fans have been introduced to provide improved home air ventilation, to supply a regular supply of fresh air and to exhaust heat from the home during hot weather.
Called a "whole house fan," this type of fan usually is installed on the roof or under a gable. Heat rises, so the attics of homes fill with super-heated air. The blower fan draws cooler air from the lower levels of the home up into the attic, where the heat is dispelled through the roof or a wall. Some whole house fans are so effective that fans are used as alternatives to or replacements for the air conditioning systems in the homes.
Attic fans, another type of air refresher blower fans, usually work in tandem with air conditioning systems. One type of attic fan draws fresh air in from the soffits of the roof and expels heated attic air out through the roof. Another type of attic fan is installed in an interior ceiling, such as the ceiling on the second floor, where air is drawn from the living spaces of the home into the attic. It is important that the air drawn into the attic is dispelled by another fan directing air to the outside or through a passive vent such as a gable vent or open window.