Ventilation or exhaust fans are an absolute must in some applications, especially in modern homes that have not been designed for maximum air circulation. Exhaust fans can keep air moving in your home to provide a fresher and healthier environment indoors.
When you think about the types of air that can accumulate in your house, you realize the necessity of exhaust fans in many cases. These handy ventilators can rid your home of pesticides, pet dander, smoke and other types of bad air, as well as to keep your home from becoming too humid. Excess humidity can spawn mold and mildew, which leads to all sorts of health problems. That extra humidity also can warp and rot furniture, cause peeling paint and ruin precious possessions.
Different Ventilation Types
Exhaust fans draw out stale and impure air from your home and bring in fresh air, often through ducts in your home. They come in several varieties:
- Ceiling-mounted
These fans expel old air through the roof of your house, usually via an external vent such as a roof cap. - Inline
These are mounted between ducting and are extremely quiet, often operating with a flex duct that is best when at least 8’ long. - Wall-mounted
These are installed on the exterior walls of the home and do not require duct work. - Exterior remote-mounted
These are also installed outside and pull stale air out rather than push it out from the inside. Most of the noise from these fans is made outside. - Kitchen range
These fans rest in the hood of your stove and expel odors and smoke while reducing moisture levels in the cooking area. - Bathroom
These fans often work in concert with lights in your bathroom, expelling odors and steam rapidly. - Dryer room
These push the moist air created by your dryer outside to the exterior of your home. - Attic/crawl space
These move the air that can sit for years without being disturbed. Most homes with attics have them.
Performance Considerations
Experts in the field advise that the air be changed at least 8 times per hour in bathrooms, 15 times per hour in kitchens and 6 times per hour in other living spaces. Exhaust fans are rated according to their CFM (cubic feet per minute) capabilities. Exhaust fans in the bathroom should have a 50 CFM rating, for instance. Kitchen fans should be more powerful, especially those in the range hood (at least 200-500 CFM, in most cases).
You also need to make sure that you have large enough ducts to remove the air blown out by an exhaust fan, as well as ducts that can resist the air pressure created within them. Helpful formulas are available online and also are provided by exhaust fan dealers.