How to Choose Your Bathroom Vent Fan

One of the most important purchases you can make for your home is a bathroom vent fan. A good vent fan will extend the life of your home, prevent unhealthy mold and mildew build-up, and keep the air inside your home from becoming stale.

For Good Measure

Measuring for the correct vent fan is actually very simple. Find the size of bathroom in cubic feet and divide that by 5.

Measuring for the correct vent fan is actually very simple. Find the size of your bathroom in cubic feet and divide that by 5.

The first factor to consider when shopping for a bathroom vent fan is the size of the room. You will need a fan with a powerful enough motor to completely turn over the air in the room in about five minutes. The measurement for air circulation speed is CFM, or cubic feet per minute. To calculate what CFM to look for, figure out the number of cubic feet in your bathroom and divide it by 5 (for the number of minutes). The result will tell you what CFM rating to look for in your bathroom vent fan. For example, if your bath is 10 feet in length, 10 feet in width, and 11 feet in height, your room is 10x10x11 cubic feet or, 1,100 cubic feet. Divide 1,100 CF by 5 minutes to get 220 CFM. To keep energy costs low, look for bathroom fans that are ENERGY STAR rated to ensure that they have an efficient CFM to wattage output ratio.

Get the Air Out

Be sure that your ventilation ducts lead somewhere outside of your residence. Simply circulating the air into your attic or elsewhere in your home will just displace mold and mildew to other areas of your home, which will lead to bigger problems farther on down the road. No need to worry about cold air from the outside finding its way through the vents; just look for a fan that has built-in dampers to prevent backdrafts. Some fans have a heater setting, too, a nice feature for those cold winter seasons.

Vent ducts should move air outside of the house to prevent mold and mildew growth.

Vent ducts should move air outside of the house to prevent mold and mildew growth.

Sounds About Right

The sound produced by vent fans is expressed by a unit of measurement called a sone. For reference, the average sone of a refrigerator is about 1 sone. Vent fans operate anywhere between 0.5 to 6 sones. Consider where your bathroom is in your home when deciding between levels of sone.

Additional Features

Bathroom vent fan/light combos provide enough light to serve as the primary source of lighting for the room. These are particularly useful in smaller bathroom layouts where ceiling space is limited. Another feature worth considering is motion sensor technology that activates the fan for a set amount of time when someone enters or leaves the room. This feature is especially helpful to parents who want to make sure their children use the fan, or owners of rental properties that want to extend the life of their homes.

An alternative to motion sensor technology is to install your bathroom vent fan on a timer that allows you to select how long you want the fan to run when you turn it on. To prevent moisture from building up, be sure to run the fan for at least the time it takes to completely turn over the air in the bathroom after bathing. The right size fan should get the job done in about five minutes.

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