How Do Dehumidifiers work?

Dehumidifiers are used all over the country rather they be a smaller portable system or a centrally installed system that moves through your duct work. While their function is rather basic, removing excess humidity from your home, their benefits are numerous.

Excess humidity in your home can cause a whole host of problems. It could be causing a damp or musty smell to come from your basement. It could be causing water to condensate on your interior windows. It could be causing mold to begin growing on your walls or curtains. Whatever symptoms you are seeing a dehumidifier can help eliminate all of them. To see all of the various benefits that dehumidifiers can offer please click here.

The question now though how exactly do dehumidifiers work? How is the water extracted? What kind should you get? Let’s take a look.

How They Work

Depending on what dehumidifier that you are looking at they can remove humidity in one of two ways.

The first is that they act like an air conditioner complete with compressor and refrigerant. The air is brought in, the air is cooled by passing over freezing pipes, the cooled air’s moisture/humidity then turns back into liquid, the cooled air is passed through a heating element to warm the air back to room levels, and then the warmed dry air is expelled back into your home. All of this is done with the use of refrigerants just like what you see in air conditioner. The only real difference is that an air conditioner does not have an additional heating element to warm the air back to baseline levels. I won’t get into the full science of the refrigeration cycle here, but if you are interested in reading more about it read our ‘How do Refrigerants Work’ article.

The second way a dehumidifier can work is through the absorption or adsorption method.  This is also known as the desiccant method. These are the most common methods especially in smaller portable dehumidifiers. There is no refrigerant used in this method. Instead, the moist air is pulled into the machine through a duct. That air then moves past a large rotating wheel of water absorbing material. While the air is on this wheel it rotates through a section that has heated hot air blown on it. After some time the rotating wheel is dried out from the hot blowing air and then the dry air is expelled back into your home.

In both cases the dehumidifier should have a sensor that will alert the machine its collection tray is full. This alert will stop the machine from operating until the collection tray is emptied of water. Most of the time they will have an indicator alerting you that the tray needs emptied. Other dehumidifier models come with a drainage hose attachment. If the hose is connected you can then drain all of the removed water into a nearby drainage area. This will work just like your central air conditioner does.

Something else to consider is what type of dehumidifier that you want for your home. It can be important when choosing what type of dehumidifier that you want: Refrigerant based and desiccant based. The desiccant models are more efficient then refrigerant models, especially in colder temperature areas. The down side is that these systems also have a smaller capacity rating.  The desiccant models are also quieter than their refrigerant counterpart. If you were looking to cool just a bedroom or two then you may look at the desiccant.

However, if you are having constant trouble with a part of your home that is hot and humid then you should be looking at the refrigerant models. A refrigerant based system will be more efficient in hotter temperatures. It all depends on temperature. If the area you are dehumidifying is below sixty-five degrees then you should go with the desiccant model and if your room is above sixty-five degrees then go with the refrigerant type model.


If you are interested in purchasing a dehumidifier then I recommend you check out our complete buying guide that I completed earlier this week. The guide goes over every possible question and consideration that should be made before purchasing a dehumidifier.