A dehumidifier has hot and cold coils that are built in the same box. The unit's fan draws the air in the room through the cold coils of the dehumidifier to condense its moisture. When this happens, as in the case of window type air conditioning units, water drips out of the unit. Dry air then goes through the dehumidifier's hot coils so it can we heated up again back to its previous temperature.



An example of a dehumidifier is an air conditioning (AC) unit. It is a device that was designed to remove heat out of an area using the principles of refrigeration. An AC is a good example of a dehumidifier because it is designed to lower the humidity in the air which goes through it.

Human bodies have natural dehumidifiers in form of sweat. When we sweat, our bodies cool because of the evaporating perspiration from our skin. Dry air, then coming from an AC unit creates provides comfort as it creates 40-60% relative humidity in an area.

As a dehumidifier, an AC unit is basically another form of refrigerator without an insulated box. It uses a refrigerant like Freon for its evaporation to cool an area. Freon is one of the many non-flammable fluorocarbons which are in use today as refrigerants.

In an AC unit, the evaporation cycle works in this manner: 1) cool Freon gas is compressed, making it high-pressure, hot gas; 2) the hot gas then goes through the set of coils in the AC unit so it can disperse its heat and then condenses into liquid form; 3) Freon goes through a valve, and through this process it becomes low-pressure, cold gas; and 4) the cold Freon gas then goes through a set of coils in the AC unit that will allow the gas to take in heat and chill the air within the area. A special type of oil is mixed with the Freon gas to lubricate the AC unit's compressor.

The coldness that a dehumidifier can provide depends on the air's relative humidity and the barometric pressure (this is sea level normal pressure). When there is 50% humidity in the air, water temperature will drop at about 6 degrees to 89F.

Change that to 20% air humidity and the temperature drops to 28 degrees to 67F. These small temperature drops affect energy consumption because the use of these AC units places a large demand on electricity especially on warm months when more units are operated.

During these peak times, more power plants must be online to cater to the large demand for energy. Studies of residential air conditioning showed that AC units wasted 40% of energy. This energy gets wasted in the form of heat waiting to be pumped out.

When you see large quantities of water running through plastic hoses at the backs of big buildings, you'll know that there are dehumidifier units inside. Many apartment and office complexes now use centralized AC units and the chilled water coming out of these systems is directed to underground pipes.