Dehumidifiers - What Do I Need to Know?

Here at Air Conditioner Home, we try to make finding the right dehumidifier a simple process, so we've compiled a list of questions you might have, along with the products that we find to be most popular and useful.

We hope this will help you in your search and with taking proper care of your new dehumidifier, but don't hesitate to call us toll free if you need more information.

See Our Complete Selection!

What are the benefits associated with dehumidifying?

AD-400 Image4Dehumidifiers lower the relative humidity of the surrounding area. In areas of high humidity, like the Southeastern United States, problems with too much moisture in the air can become especially unbearable during the summer months.

Reducing water content of the air:

  • decreases the potential for mold and fungus to appear and grow
  • helps prevent allergic reactions and other long-term health problems
  • reduces the expansion and warping of wooden furniture
  • eliminates seepage and "sweating" in the walls and ceiling, with accompanying musty odors
  • makes the air indoors feel cooler and more comfortable

What does humidity have to do with my furniture?

When the relative humidity increases, the amount of water moisture the air is holding increases drastically. Your furniture will absorb this excess moisture through the joints and cracks in the finish. In severe cases, the wood absorbs so much water that it begins to swell and expand. Pieces that previously fit together are pushed apart and nails and screws are pushed out of place. Using furniture in this condition only intensifies the problem.

Removing the excess moisture from a closed room can help to eliminate this expansion and help your furniture last longer.

WDH871 Image2A toxic mold specialist estimated that it would be expensive to remove the mold problem in my walls, but can I buy a dehumidifier instead?

Not entirely. Dehumidifiers dry the air and objects within the room (including drywall) and can help to reduce mold growth. But previous growths of mold will see little to no reduction in size.

Most molds require moisture to germinate and to continue growing, but once mold is established, it begins to store moisture within itself to survive. When the environment begins to dry, the mold will form cyst-like structures that are capable of re-germinating for years after the original infection has dried out.

For established mold growths, we suggest seeing a specialist for removal, and then purchasing a dehumidifier and/or air purifier to reduce the chances of the mold returning.

Do dehumidifiers require much maintenance?

The bulk of the maintenance for one of these units is emptying the tank periodically. How often the tank needs to be emptied will depend on the size of the tank and how much moisture is in the air.

Most dehumidifying products have warning light or alarms which warn you when they are full. All dehumidifiers will stop operation when the water tank can no longer hold anymore water. One feature to look for is an automatic drainage hose, which will save you the trouble of having to empty the tank yourself.

Aside from draining, the tanks should be washed periodically to prevent bacterial growth and should never be stored with water remaining in the tank.

EDV-2200-BL Image1How do dehumidifiers work?

Most work similarly to air conditioners. A cold coil inside the unit collects water just like a cold glass of lemonade collects water on a hot day. This condensate water drips down and is collected in a tank. After being cooled and dried by the cold coil, the air is reheated by the warm coil in the dehumidifier, so the air leaving the machine is about the same temperature as it was when it entered.

An alternate method of dehumidification uses crystals that work like sponges. Plates of specially-formulated crystals (desiccants) slowly absorb water from the air, without needing a power source. When the crystals are full, you simply plug in the unit to heat the crystals (in another location, not where you are dehumidifying) to push the water out.

What size dehumidifier should I purchase?

Dehumidifiers are sized according to how much water they pull from the air, so you will need to consider two factors:

  • How big an area do you need to dehumidify?
  • How much moisture do you need to remove from the air?

The Association of Home Appliance Manufacturers recommends the following:

AHAM Dehumidifier Sizing Guidelines
Match Room Size to Current Humidity Conditions to Find Minimum Size Ratings

Condition Without Dehumidification

500 Sq. Ft.

1,000 Sq. Ft.

1,500 Sq. Ft.

2,000 Sq. Ft.

2,500 Sq. Ft.

Moderately Damp with Musty Odors in Humid Weather

10 pints

14 pints

18 pints

22 pints

26 pints

Very Damp with Odors and Damp Spots on Walls and Floors

12 pints

17 pints

22 pints

27 pints

32 pints

Very Wet with Sweating Walls and/or Seepage

14 pints

20 pints

26 pints

32 pints

38 pints

Extremely Wet with Wet Floors and High-Load Conditions

16 pints

23 pints

30 pints

37 pints

44 pints

We recommend you buy at or over the recommended size - a larger unit will simply remove moisture more quickly from the air. A too-small unit, however, might run continuously without lowering the humidity sufficiently.

Shop for a Dehumidifier by Selecting One of the Categories Below: