Ventilation fans, also known as exhaust fans, help air circulate inside a home, which usually allows the house to stay warmer in the winter and cooler in the summer. Fans that move air in an enclosed space, such as a small attic, also can help keep mildew and mold from growing by dispersing moisture. There are several different types of ventilation fans. Some common types include in-line, wall-mounted, ceiling-mounted, exterior-mounted, and combination fans. In addition to these types, the fans can be designed for whole home air ventilation, or they can serve a specific purpose in one room, such as a stove exhaust fan.
In-line ventilation fans are usually best for houses in which a fan can not easily be installed into the ceiling. These fans are placed inside the actual ductwork of the home and used to suck air through the heating and cooling vents. The air is pushed through the ductwork and out of the house. Wall-mounted and ceiling-mounted fans are mounted directly into the wall or ceiling of a room. These suck air from the room and push it through the ductwork in the same general manner as in-line fans.
Exterior-mounted ventilation fans, also sometimes called exterior remote fans, are mounted on the outside of the home. They are typically installed in the roof or on the side of the home's exterior to pull air from a part of the house. These types of exterior fans are often used to ventilate attics and crawlspaces to keep damaging moisture from staying trapped inside.
Combination ventilation fans are ceiling or wall models installed inside the home. Combination varieties typically offer both light and ventilation. These are often found in bathrooms where the fan can be easily turned on with a wall switch or pull cord along with the light. Some three-way models also offer a small heater installed in the same fixture.
A ceiling or roof ventilation fan can serve as a general air refresher that keeps indoor air from becoming stale. Some rooms may need special attention, however, such as bathrooms. Fans installed in bathrooms pull out the excess steam and humidity to keep the room from staying too damp. Kitchens may also need a special fan — ventilation fans built into range hoods or on the ceiling above a range can help improve kitchen air quality by pulling out steam, smoke, and cooking fumes. Many homes will have better overall air quality with a combination of two or three different types of ventilation fans.