Desiccant dehumidifiers work in a different matter than standard refrigerant dehumidifiers. Fans blow humid air over a rotating tray filled with a desiccant material (one that absorbs or adsorbs water). The tray rotates saturated desiccant material (usually silica gel) into a heating area inside the dehumidifier, “baking” water out of it. This heated, humidified air is ducted outdoors; the tray rotates and the newly dried desiccant material is ready to absorb more moisture from the air.

Desiccant dehumidifiers use more energy than standard refrigerant dehumidifiers do. They usually require use of a 220-Volt electrical outlet, made available by unplugging a washing machine or dryer. Refrigerant dehumidifiers rely on downward movement of liquid water. In extremely cold conditions, this water will freeze, effectively stopping dehumidification. Because desiccant dehumidifiers don’t rely on this water movement, they will operate at temperatures well below freezing.