What Size Should My Bathroom Ventilation Fan Be?

Ordinary tasks like showering, bathing and shaving can put home-harming humidity into the air in your Grimes home. There’s good news still—a modest bathroom ventilation fan can keep you from distorted wood, mold growth, cracked drywall and other problems connected with a humid bathroom.

Even if you have ventilation fans in your bathrooms, do you know if they’re the correct size? Are they as quiet and energy efficient as they could be? Heartland Heating & Cooling is here to answer your questions.

Today’s bathroom ventilation fans are small and modern and they operate more quietly and effectively than ever before. You’ll find a great range of selections, from classic fans that will get the job done to fans with integrated heat lamps, motion sensors and heat-exchanger ventilation that helps block warmed air from escaping through your ventilation. While you have a lot of bells and whistles to select from, the most critical feature of your fan is whether or not it’s large enough to do its job.

Rated by the cubic feet per minute (CFM) of air they push, a bathroom ventilation fan should be able to exchange the air in a bathroom at least eight times an hour. With a normal 8-foot ceiling, your ventilation fan should have a CFM rating almost as high as the number of square feet in your bathroom. Thus, if your bathroom is 5 feet by 8 feet, a CFM rating of 40 would be sufficient.

If you have a taller ceiling, the equation gets a little more complex. You’ll want to multiply the width of the room by its height and length, divide it by 60 and multiply by 8. Or, to keep it easy, you can heed HGTV’s tips for bathrooms larger than 100 square feet – determine your CFM requirements by increasing 50 CFM for every toilet; 50 CFM for each shower, bath and combo; and 100 CFM for each whirlpool.

If you’re unsure if your bathroom ventilation fan is the correct size, or you know it’s time for a new one, give the experts at Heartland Heating & Cooling at call at 515-344-3579. We’re here to help you make sure you have a ventilation fan that will work hard to protect your home and keep it comfortable. 

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