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Dehumidifiers serve a few different purposes, most obviously to remove moisture from the air, typically from a basement. They can also help eliminate odor caused by moisture. Today’s newer homes are well insulated, which not only keeps heat in, but also traps moisture. With all the activities for a family of four – cooking, laundry, showers and dishwashing, as much as 20 gllons (80 L) of water can be released in a home each week. Dehumidifiers help address this moisture. However, they are no substitute for proper ventilation. Major moisture problems can result in the buildup of mold and mildew, which can lead to health problems. These major issues may come in the form of cracked foundations, substandard drainage or poor ventilation and need to be specifically addressed to resolve the problem.

For those minor problems, a portable dehumidifier is a good choice if your HVAC system does not have one built in. Even if they do, you may find the basement is still quite damp and a separate dehumidifier may be required.

Most dehumidifiers have a top-mounted air discharge, a removable plastic bucket, automatic shutoff and warning lights to indicate when the bucket is ready to be emptied. They can even be hooked up directly to a floor drain or sump pump, so there is no need to manually empty. They also will have a humidistat that will shut the unit off when optimal humidity is achieved, usually 30-50% relative humidity. Anything over that promotes the growth of bacteria.

Portable dehumidifiers come in 2 sizes – standard and high-capacity. A standard-sized dehumidifier removes up to 35.5 L of water per day. Anything more than that is considered a high-capacity dehumidifier.

Portable dehumidifiers do not carry the EnerGuide label, but do still qualify for the ENERGY STAR label. Depending on the model and size of dehumidifier, ENERGY STAR units can use anywhere from 20-60% less energy to remove the same amount of moisture as a standard model, resulting in a $20 saving per year, or $250 over its lifetime. That’s enough energy to power your refrigerator for 6 months.

Whether or not a dehumidifier qualifies for the ENERGY STAR label depends on its Energy Factor (EF), which is a calculation of the amount of water it removes per kilowatt-hour of energy used. Standard-sized dehumidifiers need to have an EF between 1.2 and 1.8, depending on their size, whereas high-capacity units must have an EF of 2.5.

What size of dehumidifier you need will depend on a few things. First, how large is the area you wish to remove moisture from? Second, what are the conditions of the area.

A damp area is one that constantly feels damp and has a musty odor. There may even be damps spots on the floor or walls.

A wet area feels and smells wet. The floors and walls sweat, and there may be seepage present.

An extremely wet area is an area with high load conditions, such as the laundry room. These areas have obviously wet floors and walls, perhaps even puddles in spots.

To find out what size of dehumidifier suits your purpose, please see the chart below.

Area to be

Humidity Conditions *
(moisture accumulation per day)

Damp 1

Wet 2

Very Wet 3

46 m 2 (500 sq. ft.)

6 L

7 L

8 L

93 m 2 (1000 sq. ft.)

8 L

9 L

11 L

139 m 2 (1500 sq. ft.)

10 L

12 L

14 L

186 m 2 (2000 sq. ft.)

12 L

15 L

18 L

232 m 2 (2500 sq. ft.)

15 L

18 L

21 L

279 m 2 (3000 sq. ft.)

18 L


24 L

What ever model you choose, be sure it is correct for the space that needs to have the moisture removed. Too small a model will not yield the results you are looking for, while too large a model may use more energy and cost more money than necessary.

 Dehumidifier Calculators
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 Dehumidifier Tips
Look for the ENERGY STAR Label
When buying new, look for ENERGY STAR products to ensure optimal energy savings.