Desiccant dehumidifiers work by using a large desiccant wheel to adsorb moisture from the process air stream. As the process air is dried, the moisture content of the wheel rises. To remove this moisture the wheel is in constant rotation and a second air stream is heated and passed through the wheel. This heated air steam picks up the moisture from the wheel, in turn drying the wheel so it is reactivated and able to continue to dry the process air.

Desiccant dehumidifiers are one of two main types of dehumidifiers. The other common type is a condensing dehumidifier. These are often used for pools or damp basements. Desiccant dehumidifier excel in dryer environments compared to condensing dehumidifiers, and are essential for low dew point applications.

The graphs below show when each type of dehumidifier is more efficient.