Attic roof fans circulate and vent the hot air that naturally rises in a home during the day. They also work to remove moisture from the attic to prevent mold and wood rot from occurring. Using attic roof fans can lower the temperature of the rooms under the attic by 5° Fahrenheit (15° Celsius). Roof-mounted powered and solar-powered attic fans are the two main types of attic roof fans.
Some attic roof fans are installed on the roof of a building. They have a mushroom-like shape that is created by the fan’s rain cover. The rain cover protects the opening of the attic roof fan and prevents precipitation from entering the attic. Some come with thermostats that automatically turn the fan on and off when the air reaches a specific temperature. A safety device known as a firestat turns off the fan when it detects a house fire, ensuring that it does not accidentally spread the fire throughout the house by feeding the blaze more air.
Solar attic roof fans utilize solar panels as a power source, making them environmentally friendly, or “green”, while lowering the humidity and heat of a home. Solar panels collect sunlight and transform it into electricity that runs the fan motor. They come in three different styles, including a standard flat base, a curb-style base and a gable-mounted base.
Standard flat-base solar roof fans are installed on normal-slope shingle roofs. A curb-base solar roof fan is installed on flat, low-slope or tiled roofs. The curb-style solar attic roof fan has a “curb” or wall that raises it up off the roof to allow the fan to work properly. A gable-mounted solar fan can be installed in an existing gable vent on a home.
Other types of attic fans include gable fans and whole-house fans. Gable-mounted attic fans are installed on the triangular point of a wall, between the slopes of a roof. They often are mounted behind an existing gable vent in the home and can have automatic shutters that close when the fan turns off.
Whole-house fans consist of a large fan installed on the floor of the attic. They are set in a wooden frame installed on a hole that has been cut through the attic floor. A hinged shutter covers the hole. The shutter opens when the fan runs and shuts when the fan is off, preventing cold attic air from seeping down into the home during winter months.