What Are the 3 Types of Dehumidifiers?

Hot and sultry, muggy and sticky, there's nothing worse in the summer time than the heaviness of the humidity. In fact, for some states it's so bad, that you are drenched in moisture just to take a walk to mailbox at the end of your short driveway. And, when that humidity makes its way indoors, the days and nights can seem virtually unbearable. Fortunately, there is a solution. Invented by Willis Haviland Carrier in 1902, dehumidifiers soon became the ideal way to cool one's home. Over the years the dehumidifier as evolved and today there are 3 main types of dehumidifiers.

All humidifiers work on the same basic principles, though each one varies somewhat based on the type. Like an air conditioner, the dehumidifier uses refrigerant. However, it does not cool the air...it actually warms it slightly which decreases the humidity thus making the room more comfortable. This is done by a fan, hot and cold condenser coils and a water reservoir.

The heat pump dehumidifier is used to pull out water form a building by using a heat pump which works much like an air conditioner pump. A fan is used to move the air across a frigid coil causing the moisture to condense. Then the droplets are collected in a bucket inside the unit. The air is then warmed by a second coil and then released back into the room at a comfortable temperature. The heat pump dehumidifier is considered the best one available.

In large industries, especially those in warmer climates, the most common type is a chemical absorbent dehumidifier. This type uses a chemical drying agent that works with a heat exchange wheel to absorb the water molecules from the air. The process pulls the damp air outside through the vents.

The third type of unit is the dehumidifying ventilator. These work with a sensor controller and an exhaust fan. These are less effective in climates where the humidity is especially high because the ventilators draw outside air into the house. Rather, the dehumidifying ventilator works great in basements but you must pay close attention to how it is working as it can depressurize a room and can cause gas spills...just be sure that if you have a gas furnace that it is properly vented and you will fine.

If you already have a dehumidifier, but it does not seen to be working correctly, there are a few things you can do. First you will want to make sure that it is the right size unit for the space it is cooling; then after you have turned the unit off, check the following:

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  Remove the cover clean the condenser and the evaporator coils.


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  Lubricate the fan motor bearings, if the motor has oil ports.


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  Make sure the humidistat is working properly by testing it with a volt-ohm. Rotate the humidistat's knob as far as it will turn in either direction. If it reads 0 throughout the process then it is time to replace the unit.