What Size Should My Bathroom Ventilation Fan Be? 07/28/2017Everyday tasks like showering, bathing and shaving can put home-destructive humidity into the air in your the Main Line home. There’s good news however—a modest bathroom ventilation fan can save you from deformed wood, mold growth, damaged drywall and other trouble associated 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? O'Brien Heating & Air Conditioning is here to answer your questions. Today’s bathroom ventilation fans are small and modern and they work more quietly and efficiently than ever before. You’ll find a large range of options, from simple fans that will get the job done to fans with integrated heat lamps, motion sensors and heat-exchanger ventilation that helps avoid warmed air from getting out through your ventilation. While there are a lot of bells and whistles to select from, the most imperative feature of your fan is whether or not it’s large enough to do its job. Assessed 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 typical 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 satisfactory. If you have a higher 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 follow HGTV’s advice 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 not sure if your bathroom ventilation fan is the proper size, or you know it’s come to the point for a new one, give the pros at O'Brien Heating & Air Conditioning at call at 610-257-7035. We’re here to help you ensure you have a ventilation fan that will work hard to protect your home and keep it comfortable. You can even schedule an appointment with us online if that’s easiest for you.