Whole House & Attic Fans

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.

Attic Fan

Powered attic ventilators, by comparison, only serve to remove some hot air from the attic.

A powered attic ventilator, or attic fan, is a ventilation fan which regulates the heat level of a building’s attic by exhausting hot air. A thermostat is used to automatically turn the fan off and on, while sometimes a manual switch is used. An attic fan can be gable mounted or roof mounted. Additional vents are required to draw in fresh air as the hot air is exhausted. Attic fans are typically used in warmer months, when temperatures in a building’s attic may very well exceed 120 °F (49 °C).