How to Calculate for Bathroom Exhaust Fans
Bathrooms require exhaust fans because of the large amount of hot water used in them. This raises the temperature and humidity level of the bathroom and the combination of warm temperatures and humidity can cause wood to warp and paint to crack and can become a breeding ground for mold and mildew. To combat this, you should install a bathroom exhaust fan large enough to circulate new air in and out about eight times per hour. The size of a bathroom exhaust fan is measured in cubic feet per minute. Does this Spark an idea?
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Instructions
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1
Measure the dimensions of your bathroom.
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2
Calculate the volume of the bathroom in cubic feet. For rectangular shaped bathrooms, multiply the length times the width times the height. For example, if your bathroom was 10 feet long, 7 feet wide and 8 feet high, your volume would be 560 cubic feet.
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3
Determine the number of times per hour you want the air to be cycled in and out of your bathroom. Eight times is generally sufficient. Divide 60 by this number to determine how many minutes it should take your fan to cycle out the air. For example, if you want to cycle out the air eight times per hour, it would need to complete one cycle every 7.5 minutes.
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4
Divide the volume of your bathroom found in Step 2 by the number of minutes per hour found in Step 3 to find the minimum rating for your bathroom exhaust fan. For example, 560 cubic feet divided by 7.5 minutes is 74.67, so you would want a fan with a capacity of at least 75 cubic feet per minute.
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