Most dehumidifiers operate best at normal room temperature (20-22 degrees Celsius). A major factor in the selection of a dehumidifier is the anticipated ambient air temperature of the room to be dehumidified. In unheated rooms, where there are temperatures of less than 15 degrees, dehumidifiers with a defrost system and a higher dehumidification performance are required if the dehumidifier is to be effective.

Standard "compressor-refrigerator" type dehumidifiers will not work well at low temperatures. Hire or buy a compact absorption or desiccant dehumidifier. They can work at low temperatures and can be a viable alternative.