How Do Dehumidifiers Work?

by Raymond Archambault
Humidificateur - Purificateur d'air

Everyone knows that dehumidifiers dehumidify a house. But what does that really mean? Unless you have an understanding of what humidity is, why it’s bad for you and your house, what dehumidifiers do to combat it, and how they do so, it is impossible to answer that question. Different types of dehumidifiers will function a little bit differently, but all of them are effective at dehumidification and improving indoor air quality. Home dehumidifiers are an excellent investment; let’s explore why and how.


What Is Humidity?

Humidity at its most basic level is a representation of how moisture is in the air. As water vapor accumulates in the air, it begins to feel heavy and muggy. Since water holds onto heat, the air temperature will rise as the humidity levels rise. Relative humidity is a term that explains how much moisture is in the air at present compared to how much moisture CAN be there at a given temperature. Hot air can hold more moisture than cold air, so relative humidity will be lower in warmer temperatures since there is a greater capacity. The reverse is true in colder temperatures; relative humidity will be higher since cool air can’t hold a large amount of water. Relative humidity is what a dehumidifier’s humidistat measures.


Why Is Indoor Humidity Bad For You and Your Home?

Humid air in your home can have a number of detrimental effects on your home and your health. Let’s discuss the home first.

Moist air in your home can produce a musty smell and an uncomfortable, oppressive living environment, but there can be some more serious consequences that result as well. The effect on your air conditioning system is one of the problems that most people don’t recognize. Setting the thermostat on your air conditioner means the unit has to work constantly to maintain that temperature. If your HVAC system needs to combat moisture in the air as well as a higher temperature, it is going to have to work really hard and pull more electricity to accomplish its task. Not only does the excess moisture make the air conditioner less energy-efficient, but it will also raise your energy bill and impact the environment.

Water damage can also result from excess humidity in the home. This can rot the wood that structurally supports your home, and it also create a prime environment for mildew and mold growth. Condensation on your windows that drips to damage the window seal and peeling paint and other finishes are two other consequences of warm air that contains too much moisture, both of which affect the look and integrity of your home.

High humidity can have a number of negative effects on your health as well. Increased populations of dust mites and pathogens will lower the effectiveness of your immune system and make illness more common. This will also affect your ability to combat allergens and make symptoms of pre-existing conditions such as asthma worse. While dry air can also affect allergies and asthma in a negative way, prompting people to purchase humidifiers instead, there is a fine line between too dry, acceptable levels, and too humid.

Dehumidifier Water For Plants

What Does A Dehumidifier Do?

At their core, dehumidifiers reduce the level of humidity in a space, and to a lesser extent, they improve the air quality as well. While an air purifier will always be the most effective way to clear dust, microorganisms, and other contaminants out of the air, dehumidifiers do their part as well. Dehumidifiers lower the temperature of the air and remove a lot of moisture from it. After that is done, they will recirculate cool dry air back into the home. This will improve the conditions of your home, improve your health, and even save you some money on air conditioning. If you purchase an energy star certified model, you’ll also save money on the power that the unit itself is drawing. No matter what room temperature you like to maintain or what region of the house the humidity affects the most (from crawl space to living area), a dehumidifier can correct the detrimental effects of moisture buildup in the air. Let’s get into the nitty gritty of how each type of dehumidifier works.


How Compressor/Refrigerant Dehumidifiers Work

A compressor dehumidifier uses refrigerant to keep a section of coils quite cold. The compressor draws in air over the coils, instantly cooling the warm humid air and creating condensation. The condensation drips down into a reservoir at the base of the unit. Since the water vapor in your home is liquified by this process, the air that comes out is less humid. The cooler, dry air is then blown back out to your space very similar to an air conditioner. These dehumidifiers usually also have a fan setting that moves air without dehumidifying, as well as multiple speed settings for noise consideration at night or higher efficiency during exceptionally humid days.


How Desiccant Dehumidifiers Work

A desiccant dehumidifier is a bit different. Instead of cold coils, it uses a desiccant to remove moisture from the air. A desiccant is like a sponge that soaks up the humidity so that air coming out the other side is drier. Contrary to a compressor dehumidifier, the air that is released will be warmer than your ambient room temperature instead of cooler. The main benefits of this type of dehumidifier over compressor dehumidifiers are lower operating noise and the ability to operate in cooler temperatures. As with compressor dehumidifiers, the collected water can be drained manually or with a drain hose.


How Whole-House Dehumidifiers Work

A whole-house dehumidifier is a permanent unit that is installed by a professional with your HVAC system. As your normal air conditioner operates, the excess moisture is removed through the added dehumidifier so that the air circulated around your home is healthier. These units can usually cover up to 5000 sq/ft since air from your entire home passes through the system. Since the other portable dehumidifiers can only dehumidify one area at a time, this system is ideal for multiple-story homes, larger homes, or extra-humid homes that need a more powerful dehumidifier.


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