Dehumidifiers operate in a fashion similar to air conditioners. They use compressed coolant gas, usually Freon, to remove heat and humidity from the air. In an air conditioner, the coolant is moved outside the home, and the heat is dispersed there. In a dehumidifier, the chief concern is removing humidity, not reducing temperature, so the heat is dispersed inside the home, allowing dehumidifiers to be run without a vent to the outside.
Parts of a Dehumidifier
A dehumidifier contains a compressor, a condenser and an evaporator. Inside the unit, attached to the compressor, is a copper coil filled with Freon. The Freon in the coils is under high pressure. These coils can leak, and they require a Freon recharge from time to time just as air conditioners do.
A dehumidifier removes humidity, or evaporated water, from the air by passing indoor air across its cold Freon coils. These coils "sweat" just as a cold glass of water sweats in a hot room. This sweat is composed of the evaporated water in the air, and the dehumidifier reduces indoor humidity by collecting the sweat, or condensate, and disposing of it.
Freon in the Dehumidifier
The Freon in a dehumidifier acts to condensate the indoor humidity and, briefly, cools the air. As indoor air is blown across the cold Freon coils, the compressed Freon absorbs heat, as well as humidity, from the air. The heated Freon is cycled to another set of coils, over which the air passes. This warms the dehumidified air back up to room temperature before releasing it from the unit back into the home.
Freon is a dangerous gas, and Freon leaks should be taken seriously. A dehumidifier that is leaking or damaged should be treated with the same care and respect as an air conditioner. Do not attempt to repair or recharge a dehumidifier if it is not indicated for user service. If you suspect Freon is leaking from your unit, remove it from the home and place it outside, away from open flame.
Andrew Leahey has been a writer since 1999, covering topics as varied as technology how-to guides and the politics of genetically modified organisms to African food supplies. He is pursuing his J.D. while renovating an 1887 farmhouse located in the New Jersey Pine Barrens.