Abstract: A dehumidifier for converting warm moist air to dry cool air. The dehumidifier includes a fan for delivering warm moist air to a plenum chamber, a dehumidifier chamber mounted adjacent to and communicating with the plenum chamber and provided with a condensing surface, a device for supplying a refrigerant to the dehumidifier chamber, and a structure for supplying short bursts of heat to the condensing surface. The condensing surface can be tapered or straight lengthwise and can be of any cross-sectional shape. Further, the condensing surface can comprise a plurality of air passages, again tapered or straight and of any cross-sectional shape.