A dehumidifier is a household appliance that reduces the level of humidity in a room.

They usually work by drawing moist air over a refrigerated metal coil with a fan. Since the saturated vapor pressure of water decreases with decreasing temperature (i.e. cold air can hold less water vapor), the water in the air condenses, and drips into a collecting bucket. The air is then reheated by the warmer side of the refrigeration coil.

Most dehumidifiers can be adapted to connect the drip output directly to a drain. Manufacturers may price dehumidifiers differently solely on the size of the collection bucket. There are usually sensors to detect when the collection bucket is full.

Air conditioners automatically act as dehumidifiers when they chill the air and thus need to handle the accumulated water as well. Window units simply allow the water to drip outside. Central air conditioning units need to be connected to a drain.

See also humidifier, an appliance that increases the humidity of air.

External links

• Dehumidifying and Drying Air From DoItYourself.com
• Dehumidifiers Guide from About.com
• How Dehumidifiers Work Article by RepairClinic