What are Dehumidifiers?

Most folks often do not think about the environment or the air within their home. This is why it is so common to see air conditioner filters go months on end without ever being changed. It’s just not something a lot of people give much thought about. I’m guilty of it as well. It is when you, or someone in your family, begin having trouble breathing due to allergens in your home’s atmosphere that we all take notice and begin to take steps to improve the air circulating in our home. 

One of the first steps to reducing allergens in your home is to regularly change your air filter. I won’t get into all of the details on air conditioner filters here, but if you are interested on what the best are please click here to view our filter buying guide. 

Besides changing your filters regularly another big step to cleanse the air in your home is to purchase and began running a dehumidifier. In this article we are going to take a look at what dehumidifiers are, how they work, and what size you should look at when purchasing for your home. Let’s dive in!

Understanding Humidity

Before we get into what exactly a dehumidifier is we first need to explore what humidity is within your home. First, let’s start with the basic concept of humidity. Humidity in short, is water vapor in the air. This water is in vapor form and is not in the form of fog, clouds, or rain. A desert will typically have low humidity whereas a jungle will have very high humidity. 

Having excess humidity in your home can cause a host of problems. Humidity is not visible to the naked eye, but there are signs of it. For example, if you take a hot shower and then step out of the bathtub and notice the mirror is fogged over. That is an example of the humidity displaying itself to you. You normally see humidity problems in enclosed rooms with poor ventilation such as bathrooms or kitchens. You may also begin to see water droplets forming on the inside of your windows, and in some cases even along your interior walls. These are all examples of excess humidity within your home.

So, what’s the big deal if your home has excess humidity? Too much humidity can cause problems, especially to those in your home that suffer from allergies or asthma. A high humidity environment is perfect for dust mites, mildew, fungi, and mold to thrive in. These allergens can result in a stuffy nose, itchy or watery eyes, sneezing, difficulty breathing, and even skin rashes. In extreme cases the mold or fungi can cause severe asthma symptoms. Reducing the humidity in your home can prevent these allergens from taking root.

My father is a rather severe asthmatic. To the point where my mother has to warn him that she will be vacuuming. He can’t be in the house for hours afterwards or else he’ll have a flare up. To help mitigate his symptoms they have a central humidifier installed as well as multiple air purifiers throughout the home. Even with all of this he still has trouble on certain days. I cannot even imagine how bad it would be without these extra protections of air quality.


Well, as you may have guessed a dehumidifier does just that. It removes excess humidity from your room or home. It does this by taking in air from your home, removing the humidity from it, and then expelling that air back into your home. The removed humidity turns to moisture that is collected in a tray that you will need to empty from time to time.

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 a 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. 

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 it’s 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.

Why Do I Need a Dehumidifier?

 Removing humidity makes your home less desirable for mold, mildew, fungi, and dust mites. Along with stopping the growth of mold or mildew a dehumidifier will help to remove the smell of these allergens. If you ever noticed that your basement has a musty or damp smell then a dehumidifier will work to solve that problem.

In extreme cases of excess humidity mold can began to form on your walls, curtains, and even on your clothes or bed sheets. I’ve never been in this situation, but I get a little sick just thinking about it. Can you even imagine mold on our clothes?

Dehumidifiers will reduce the allergens we mentioned above which will result in easier breathing in your home and will also reduce skin irritation. Without the water in the air you don’t have to worry about mold growing on your favorite pair of jeans! The amount of dust in your home will be reduced and the amount of time to dry your clothes. Even your perishable foods like cereal and bread will last longer in homes that run a dehumidifier. There are so many benefits to running a dehumidifier in your home.

Overall, dehumidifiers are rather quiet when operating and most people won’t even notice them once it has been plugged in and turned on. Adding a dehumidifier to your home may actually shrink your monthly energy costs during the summer. Without a dehumidifier your air conditioner will do its best to remove the excess humidity from the air. If you have excess humidity then your air conditioner will be working overtime to remove the heat and humidity. Having a dehumidifier running in your home will reduce the load on your air conditioner and may actually prolong its service life.

What Size Dehumidifier Do I Need?

Ok, so now we know what dehumidifiers are and why you may need to purchase one. The next question is what kind and what size of dehumidifier should you get? If you look online you will see dozens of different brands, sizes, and choices. But, which one is best for you and your home? 

Firstly, you need to determine what you intend to use the dehumidifier for. Are you going to be using it in a damp basement? Your master bedroom? Or, perhaps, in your kitchen/living room combination area? Knowing what room you will be using the appliance is key as you will have to purchase the right sized dehumidifier to ensure that the correct amount of moisture is removed from the air.

Once you have room chosen you now need to measure the square footage of said room. The square footage number will help you in determining just what size dehumidifier that you need. To find the square footage you need to measure the width and the length of the room. Let’s say for example you are measuring for a bedroom that measures ten feet long and twelve feet wide. Ten times twelve equals one-hundred and twenty square feet. 

These square footage measurements will aid you in picking a portable dehumidifier. However, if you are looking to dehumidify your entire home then you may look at a whole home dehumidifier. These units can actually be attached to your central air conditioner and be routed through your central duct work. While the cost may be expensive at first you will end up seeing monthly savings on your energy bill and a longer life from your central air conditioner due to the dehumidifier taking some of the work off of the AC. These whole system dehumidifiers can work on homes up to three-thousand square feet.

Determining Dampness

Before you purchase you should keep in mind that once you determine the minimum capacity you need  for your room that you should always go up slightly. By going up in capacity, say from a twelve pint to a sixteen pint, you are able to increase the overall efficiency of your dehumidifier. This is because the larger unit will not have to work as hard as a unit that was right at the minimum level.

When you have your square footage determined you next need to figure out how damp the room is that you are trying to dehumidify. There are a few different dampness ratings that we can assign to your room. Knowing these will allow us to guide you on what kind of dehumidifier to purchase.

Moderately Damp – When you enter the room you may notice that the air feels clammy or even damp. There may also be a musty odor when the weather is humid outside. This may be a lot of your basements. The recommend capacity for a moderately damp room is between ten to twenty-six pints, or between five to twelve liters.

Very Damp – When you enter this room you may notice that it always smells musty and the air feels clammy or damp. You may even notice damp spots on the floor, walls, or windows.  The recommend capacity for a very damp area is between twelve to thirty-two pints, or between five point seven to fifteen point one liters.

Wet – When you enter this room you may notice that it always smells musty and the air feels clammy or damp. You will also notice water beading on the floors, walls, windows, or elsewhere. You may also see moisture seeping at the edges of the room. The recommend capacity for a wet area is between fourteen to thirty-eight pints, or between six point six to eighteen liters.

Very Wet – When you enter this room you may notice that it always smells musty and the air feels clammy or damp. You will also notice water beading on the floors, walls, windows, or elsewhere. You may also see moisture seeping at the edges of the room. The difference here though between wet and very wet is that with the very wet section you will notice actual standing water on the floor. The recommend capacity for a very wet area is between sixteen to forty-four pints, or between seven point six to twenty point eight liters.

Other Buying Considerations

Along with the choosing the right size there are other, more minor, factors that should be taken into consideration. The first is the overall portability of the appliance. If you are buying a dehumidifier for one of your rooms, or even your basement, how easy is it to move? Does it come with rollers, or does it have to be carried? This may not mean much if you intend to set it and forget it in one room, but if you want the ability to move the dehumidifier around then portability definitely worth reviewing.

Another small factor is the overall size of the tank that will be holding the water that is removed from the air. Obviously, the larger the tank the less often you will have to empty it. This is just more of a convenience factor then anything though. The size of tanks can vary wildly from model to model. You may also even find some units that come with a drainage hose that can be fed to your basement drain or even your sink. All of this is a matter of preference, obviously the easiest solution is going with the hose option.

Something else to consider is what type of dehumidifier that you want for your home. In an earlier section we discussed the two types of dehumidifiers: 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.

The ideal humidity setting in a room is between thirty to fifty percent. In most cases the dehumidifier  you chose will have a setting to allow you to customize the humidity within the room. You may have to play around with this setting until you find the exact number that works for you and your home.


Dehumidifiers can be a great help in aiding in the overall comfort of your home. If you or someone in your family is suffering from allergies or even asthma installing a dehumidifier is one of the first things you should do. Now, It’s not a cure all… nothing is, but it very well may help aid in their day to day comfort.

 Even if you don’t have someone in your home who is suffering from allergies a dehumidifier is a great solution for a damp or wet area. A lot of folks set these up in their basements to get rid of that mildew and damp smell.