What Size Should My Bathroom Ventilation Fan Be? 07/28/2017Everyday tasks like showering, bathing and shaving can put home-harming humidity into the air in your Opelika home. There’s good news though—a simple bathroom ventilation fan can save 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 proper size? Are they as quiet and energy efficient as they could be? Farnell Mechanical, Inc. is here to answer your questions. Today’s bathroom ventilation fans are small and sleek and they operate more quietly and efficiently than ever before. You’ll find a great range of options, from simple fans that will get the job done to fans with built-in heat lamps, motion sensors and heat-exchanger ventilation that helps block warmed air from getting out through your ventilation. While you have a lot of bells and whistles to pick from, the most critical characteristic of your fan is whether or not it’s big enough to do its job. Rated by the cubic feet per minute (CFM) of air they move, a bathroom ventilation fan should be able to replace the air in a bathroom at least eight times an hour. With a standard 8-foot ceiling, your ventilation fan should have a CFM rating about 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 satisfactory. If you have a taller ceiling, the equation gets a little more difficult. 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 simple, you can use HGTV’s tips for bathrooms larger than 100 square feet – determine your CFM requirements by adding 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 proper size, or you know it’s time for a new one, give the professionals at Farnell Mechanical, Inc. at call at 334-524-2458. 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. You can even arrange an appointment with us online if that’s easiest for you.