How does the Dehumidifiers Work

Dehumidifiers can help prevent and, in some cases, repair damage to your home.
If you live close to the equator or near a coastal region, you probably hear your local weatherman say the word "humidity" all too often. But no matter where you are, you've surely experienced it -- that muggy, heavy feeling that fills the air, often when it's rainy, foggy or hot outside. It can make your hair frizzy and may seem to dampen everything, including your mood.
When people complain about humidity, for the most part they're talking about relative humidity. Depending on temperature, air can hold a fixed amount of water vapor; relative humidity is the ratio of actual vapor in the air to this fixed amount. For example, at a temperature of 68 degrees Fahrenheit (20 degrees Celsius), one cubic meter (35 cubic feet) of air can hold about 18 grams (.6 ounces) of water. This would be a state of saturation, otherwise known as 100 percent relative humidity.
That's a lot of jargon to describe a level of humidity that, for many people, can feel extremely uncomfortable. When this humidity seeps into your home, it can make rooms feel stuffy and perhaps even smell musty. Beyond these superficial discomforts, too much humidity can have some more serious disadvantages, too. An overly humid home can lose its structural integrity, attract pests like silverfish and centipedes, and even make you sick.
In an average home in which the temperature is 68 degrees Fahrenheit, the relative humidity should ideally be between 30 and 50 percent. If you're struggling to reach that range, a dehumidifier may come in handy. Dehumidifiers remove excess moisture from the air, improving the comfort and health of your home.
Dehumidifier Basics
Imagine enjoying a soda during a particularly warm day. When you pick up the can, you might notice that it's wet -- there's moisture on the outside. Why is that? As air loses heat, it also begins to lose its ability to retain moisture; the colder surface pulls and collects water from the warmer air, creating condensation. Your dehumidifier does pretty much the same thing. Most dehumidifiers can be broken down into five component parts:
·         Fan Compressor -- This compresses and expands a refrigerant gas like freon to cool the dehumidifier's coils.
·         Reheater -- This captures and collects heat that the cooling process generates.
·         Compressor cooling coils
·         Reservoir
How do all these parts fit together to pull moisture from the air? It's fairly simple, but very effective:
1.      A fan collects air from the surrounding area and pulls it into the dehumidifier.
2.      As the air passes through, it comes into contact with the dehumidifier's cooled coils. These coils use condensation to pull moisture from the air. The collected moisture remains on the coils and drips into the dehumidifier's reservoir.
3.      The dehumidifier reheats the air and exhausts it back into the room.
A dehumidifier usually has a removable plastic bucket for a reservoir; most buckets also have a place where you can hook up a hose so the collected water can drain straight into a floor drain or pump. This frees you from having to remember to dump out the water. But don't worry too much about the reservoir overflowing -- most dehumidifiers also have an automatic shut-off. If you're using a dehumidifier in extremely moist conditions, however, or if you need to keep your dehumidifier on all the time, you should look into a unit with a built-in condensate pump, which regularly pumps water out of the unit's reservoir rather than simply relying on gravity to empty it as a hose does.
Many dehumidifiers also have a humidistat, which allows you to set your desired level of relative humidity. A humidistat has two parts: a sensing element and a relay amplifier. The sensing element includes two alternate metal conductors, and changes in relative humidity will cause electrical resistance between those conductors. The relay amplifier measures this resistance and sends a signal to turn the dehumidifier on or off. These basic components add up to a device that may make your home feel a whole lot better.
Could your air conditioner help reduce humidity in your home, too? If you have an A/C, it functions similarly to a dehumidifier, pulling warm air in and letting it cycle over cold coils. The difference is that it does not reheat the air before exhausting it -- that's how it keeps your space cool. Also, your A/C does not have a humidistat and thus cannot detect relative humidity -- just temperature. Once it succeeds in cooling your home to your ideal temperature, it may stop running. This might allow the humidity to climb again, making your house feel like it's hotter than it actually is.

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