The size of dehumidifier you buy depends on a couple of factors: the size of your basement and the humidity level in your home.The rule of thumb is as follows: large, wet areas will need larger units to work effectively than will small, damp areas.

Dampness Level

According to the Association of Home Appliance Manufacturers (AHAM), you'll need a dehumidifier with a removal capacity of 10 to 22 pints for moderately damp spaces, 12 to 27 pints for very damp spaces and 14 to 32 pints for wet spaces. The removal capacity refers to the amount of water collected over a 24-hour period. The AHAM defines moderately damp conditions as those that "feel damp and smell musty only in warm, humid weather" and very damp conditions as those that "always feel damp and smell musty. Walls and floors show damp spots." Wet areas will have visible mold and mildew damage and show signs of water seepage. Overall, there will be a wet smell and feel to the room. Use a hygrometer to measure the exact humidity level in your basement. A hygrometer is a device that measures relative humidity, or RH level. The higher the RH level, the larger the dehumidifier you'll need to lower the humidity level.

Room Size

Once you've determined the severity of the problem, you'll need to calculate the square footage of your basement. Areas under 500 square feet can use the smallest dehumidifier relative to its moisture conditions, while large areas in excess of 2,000 square feet will need the largest dehumidifier size relative to the room's moisture conditions. Areas that measure approximately 1,000 to 1,500 square feet will require dehumidifier sizes somewhere between the two extremes. Generally speaking, a 14- to 20-pint dehumidifier is appropriate for a 1,000-square-foot space, and an 18- to 26-pint dehumidifier is appropriate for a 1,500-square-foot space.

Source:

Efficiency Vermont

Canada Mortgage and Housing Corporation