Those looking for general dehumidifiers will find they have vastly different needs than those cleaning up serious water damage or covering a large commercial building. While most units essentially work the same, people dehumidifying the home need a lot less power and speed.
Heat pumps use a fan to pull air over a near-freezing heat exchange coil. The water in the air condenses on the coil before being drained into a holding tank. A second coil reheats the air and sends it back into the room. Heat-pump dehumidifiers are known for increasing indoor air temperatures through heat generated during the process. Heat-pump machines usually cost the most, at several hundred dollars for midrange capacity.
Chemical-absorbent units are designed for use in hot, humid climates. They soak up moisture from the air using a drying agent, or "desiccant," such as silica gel. An air loop dries out the silica, venting the warm, moist air outside through the ductwork. Chemical-absorbent dehumidifiers use a lot of energy, even when powered by natural gas.
Dehumidifying ventilators work best in problem basements located in colder climates. When humidity reaches a pre-set level, indoor air is exchanged with outdoor air. There are dangers relating to gas leaks associated with some dehumidifying ventilators, so talk to a professional. Carbon monoxide detectors are essential in homes with ventilators.
Do it yourself
Some people forgo dehumidifier purchases, choosing instead to use road de-icing salt (calcium chloride) to absorb moisture from the air. Although it has been said to work wonders, it's not recommended for use in homes, especially ones with kids. Although the dangers are considered relatively small, it has the potential to irritate or burn skin and eyes, and it can cause burns to the mouth and stomach if swallowed. Plus, its dust can cause upper-respiratory-tract irritation. It is also corrosive to some metals.
Heavy-duty dehumidifying needs
Sometimes the average residential dehumidifier just isn't enough. That's where refrigerant or desiccants and air exchangers dehumidifiers come in. The large, expensive machines can clean up water damage faster than anything around and are often available for rent.