A desiccant is a material that absorbs water and will be familiar to anyone who has ever found a small pack of crystals, labelled "silica gel", packaged with a camera, computer or some other product. In an air conditioner, however, the air passes over the cold evaporator coils and then directly into the room. Some dehumidifier models can tie into plumbing drains or use a built-in water pump to empty themselves as they collect moisture. A novel thermo-mechanical anti-icing/de-icing system using bi-stable laminate composite structures with superhydrophobic surface" (PDF). For example, if the humidity rises to 65% or higher in a living room, mould growth is much more likely.

Many portable dehumidifiers can also be adapted to connect the condensate drip output directly to a drain via a hose. However a desiccant dehumidifier will generally extract moisture at a faster speed than a compressor, therefore it is debatable as to whether a desiccant dehumidifier is more expensive to run.However, on the comfort devices rather than simply be exhausted away the warm, moist air is passed over a cooling condenser element where condensation collects and drains into a container.

Dehumidifiers which work according to the absorption principle are especially suited for high humidity levels at low temperatures. If you have other questions about choosing a dehumidifier that do not seem to be covered by the information below, then you can try our Dehumidifier FAQs (Frequently Asked Questions) page. This pre-warmed air then passes through the heat pump condenser (F) where it is heated by the latent energy removed during the condensation process as well as the energy input to the compressor. As the substance (aka the refrigerant) moves from the capilliary, which restricts the flow and increases the pressure, into the evaporator it cools quickly to a temperature well below the ambient room temperature.Fresh air is then introduced to replace the amount that was extracted and the mix is discharged by the supply fan (G) to the crossflow plate exchanger (B) where it is heated by the extract air from the pool. The water that condenses on the evaporator in an air conditioner is usually routed to remove extracted water from the conditioned space. Below that there’s a further table that uses five different temperatures to show how it influences the absorption capability.