There are many choices of bathroom exhaust fans available today. Our information sheet is designed to help you make an informed decision. Popham also encourages you to visit local business resources such as Ferguson Enterprises, Ruxer Service & Supply, and Winnelson to learn more and to view products in person. Additionally, you may enjoy researching online. Popham does not endorse specific resources, but only offers them as a convenient source of information.
A shower generates a tremendous amount of steam and moisture, which causes deterioration of plaster or wallboard, paint, and wallpaper. Mold and mildew flourish in these conditions. Moisture will swell and rot wood. A bathroom exhaust fan is critical for the longevity of the wall and ceiling finishes as well as for keeping mold and mildew at bay. Some bathroom fans connect to the same switch as a light fixture. If you leave the room and turn Some bathroom fans connect to the same switch as a light fixture. If you leave the room and turn out the light, the fan turns off. It’s better to have a separate switch for the bathroom fan to ensure that it stays on long enough following a shower. The Home Ventilating Institute recommends that a fan should be left on for 20 minutes more to clear humidity adequately and to ensure moisture and condensation in the fan body or ducting is minimized. See information below about a fan timer or sensor.out the light, the fan turns off. It’s better to have a separate switch for the bathroom fan to ensure that it stays on long enough following a shower. The Home Ventilating Institute recommends that a fan should be left on for 20 minutes more to clear humidity adequately and to ensure moisture and condensation in the fan body or ducting is minimized. See information below about a fan timer or sensor.
Your existing duct is probably 3 or 4 inches in diameter. If your new fan can connect to the existing duct, your new duct work may not have to be snaked through a ceiling or crawl around in the attic. Check with a contractor before purchasing an exhaust fan.
You need a fan with a CFM rating that is high enough for the size of your bathroom. According to the Home Ventilation Institute, a properly sized exhaust fan will be able to change the air in the room eight times per hour. To determine the CFM required for your bathroom, calculate the cubic feet of your bathroom by multiplying the length by the width of the room. Then multiply that number by the height of the room. Divide that number by 60 (the number of minutes in an hour) and multiply it by 8 (the recommended number of air changes per hour). This calculation will give you the CFM required for your bathroom exhaust fan. If you oversize the exhaust fan, the room may become drafty.
A sone is a measurement of sound. The lower the number rating, the lower the sound. If you prefer a quiet fan, choose one that is rated at 1.5 sones or less. If a noisier fan is preferred, which hides toilet flushing and other noises, try 4.0 sones. Noise comparisons can be heard on YouTube.
Ceiling mounted fans are the most common. It’s the perfect location since hot air rises. You can choose a fan, a fan/light combination, or a fan/heater combination.
Exterior mounted fans have the motor installed outside of the bathroom in the attic or other utility area. This arrangement greatly reduces the noise from the fan motor. A common installation technique uses one fan motor to service several rooms. The duct work from each room is connected in the attic.
In a standard size bathroom (5’ x 8’), the center of the room is fine. This will service the bathtub/shower as well as the toilet area. An additional fan will be needed in a larger bathroom, especially if the toilet is compartmentalized. A moisture proof or vapor proof exhaust fan can be installed directly over a tub/shower area. A GFI (Ground Fault Interrupter) circuit is required for this type of installation. Wall fans are the least desirable because they will not exhaust the heat and moisture that rises to the ceiling.
It’s best to let a fan run for a few minutes after a bath or shower. Leaving a fan on too long wastes energy. Be sure to choose a timer that’s rated for motors, not just lighting. Another choice is buying a fan with a built-in sensor that automatically turns off when the correct humidity level is reached.
The only ventilation required in a bathroom by code is a window, but it does not provide air circulation, and it may not be convenient to open a window when it’s cold or rainy. An open window raises privacy issues as well.
A bathroom exhaust fan will provide air circulation that will move the heat and moisture to the outside of the house, reducing the humidity level and making the room more comfortable. The life of paint and wallpaper will be increased, and mold or mildew will be reduced.