How to Calculate for a Dehumidifier
Dehumidifiers are most often used in crawlspaces to reduce the moisture in the air. There are two important factors for dehumidifiers: the air flow rate, measured in cubic feet per minute, and the dehumidification capacity, which measures how much moisture the dehumidifier can remove from the air. When choosing a dehumidifier, make sure it meets both the minimum air flow and minimum dehumidification capacity requirements. Does this Spark an idea?
Instructions
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Determine Minimum Flow Rate
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1
Determine the how moist the air in the area that will be dehumidified is on a scale from moderately damp to very damp to wet to extremely wet. Moderately damp is the more common and is characterized by a damp feeling and musty smell if the weather is humid. Extremely wet areas are characterized by having standing water.
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2
Determine how many air changes per hour you need based on how moist your air is found in step 1. A moderately damp area needs three changes per hour and an extremely wet area need six changes per hour.
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3
Calculate the volume of the space your dehumidifier will be responsible for serving by multiplying the length times the width times the height. For example, if the area is 15 feet long, 10 feet wide and 6 feet high, the volume would be 900 cubic feet.
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4
Multiply the number of air changes per hour found in step 2 by the volume found in step 3. For example, if you need four air changes per hour and your volume is 900 cubic feet, you would get 3,600 cubic feet per hour.
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5
Divide the number found in step 4 by 60 to determine the cubic feet per minute rate of your dehumidifier. For example, if you have 3,600 feet per hour, your minimum rate for the dehumidifier would be 60 cubic feet per minute.
Determine Dehunidification Capacity
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6
Determine the how moist the air in the area that will be dehumidified is on a scale from moderately damp to very damp to wet to extremely wet. As stated in the previous section, moderately damp is the more common and is characterized by a damp feeling and musty smell if the weather is humid. Extremely wet areas are characterized by having standing water.
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7
Determine the square footage of the area the dehumidifier will serve by multiplying the length times the width. For example, if your room is 25 feet long and 20 feet wide, then the square footage is 500.
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8
Use a sizing chart found online to determine the number of pints per day the dehumidifier needs to be capable of handling (see the Resource section). For example, a dehumidifier in a 500 square foot area that is wet needs to have a capacity of 14 pints per day.
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