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Buying a Dehumidifier: A Comprehensive Guide

Choosing a dehumidifier is a task filled with jargon and acronyms - we're here to simplify it!

Quick Links

What is a dehumidifier?
Effects of high humidity
Choosing the right dehumidifier
Capacity and coverage area
Dehumidifier styles and features


Like heating and air conditioning systems, dehumidifiers have become crucial components of conventional homes. Most of us prefer humidity levels in the mid 30% area, and over 45% can be hazardous to our home and health. Here are some important things to consider in choosing the best dehumidifier for you and your family.


What is a dehumidifier?

A dehumidifier is a type of home appliance that is used for minimizing the level of humidity indoors for various purposes. It removes excess moisture from your air, which can otherwise lead to mold and mildew growth. The long term health detriments from these allergens can be substantial. Dehumidifiers are utilized to promote better indoor air

Sunpentown SD-70E
Sunpentown SD-70E

quality. They come in a variety of styles and sizes to effectively meet various standards and requirements of homeowners. Dehumidifiers are also used in other areas such as offices and industrial workplaces to maintain the quality of tools, equipment, and furniture.

A typical dehumidifier works by sucking in the surrounding air through a fan. This high humidity air then passes through the cooled coils of the unit and goes through condensation. Through this process, moisture is effectively separated from the air; it is then collected into a reservoir. Clean and moisture-free air is then dispersed back into the room via the dehumidifier’s reheater.


Effects of high humidity

Most areas experience high humidity at least occasionally during the year, and outside humidity can directly affect the indoor levels. Areas that are not properly ventilated will also be prone. Daily activities like cooking, drying clothes, and hot showers also contribute to humidity. High humidity can lead to:


  • Increase in energy bills: The air feels heavy, hot, and uncomfortable. The home feels muggy and hotter than it actually is. Because of that, people tend to crank the A/C to cool down the home.
  • More frequent allergy symptoms: High humidity can cause more allergens to form inside your home such as bacteria, fungi, and mold.
  • Damage to your home: The effects on your home can be even worse than the effects on your body. High humidity leads to increased condensation on walls, pipes, and toilet tank. This can leave your air feeling thick and muggy, and can lead to mold and mildew. Carpet and wood floors are also affected by high levels of humidity. Once mold and mildew has gets in there, it is very hard to remove. This is why it is imperative to lower humidity levels with a dehumidifier.


High humidity can be detrimental to one’s health. It promotes the growth of bacteria and Bacteriakeeps our bodies very hot. When humidity levels are high, we have to sweat a lot more to expel the same amount of heat. Furthermore, high-humidity environments are perfect for the development of mold and mildew. The quality of your wooden furniture can also deteriorate due to humidity. Paint peeling and foul odors can also be direct events of excessive humidity. Dehumidifiers help treat all of these issues and more.



Choosing the right dehumidifier

It’s hard to keep up with all of the different variations of dehumidifiers. There are different types for residential, commercial, and industrial users. No matter your situation, keep the following factors in mind:


  • Size and portability – The size of a dehumidifier proportionally relates to the volume of air it can process. If you are planning to use a single unit to dehumidify your entire home, it is best to go for a larger unit. Medium and small-end dehumidifiers are best for apartments or specific in-home areas, such as the living or dining room.  There are also portable dehumidifiers for those who travel or simply wish to have a smaller unit than be taken from room to room. They are lightweight, compact, and come with carrying handles or rollers.


  • Air changes per hour To determine which dehumidifier is right for your needs, you need to look at the air changes per hour (ACH). This calculates how many times per hour air will circulate through the dehumidifier. The higher the humidity in your home, the higher the recommended ACH would be.  The levels are summarized here; please see the chart further down to find the right dehumidifier capacity for your home.
    • Extremely Wet: Humidity levels are between 90%-100%. The recommended ACH is 6.  You can see large puddles or have standing water.
    • Wet: Humidity levels are between 80%-90%. The recommended ACH is 5. This is usually classified by visible mold and mildew, and the room has visible leakage.
    • Very Damp: Humidity levels are between 70%-80%. The recommended ACH is 4. The room will feel damp and smell of mold or mildew regardless of weather.
    • Damp: Humidity levels are between 60%-70%. The recommended ACH is 3. The room will have a musty smell or some mold, but only in humid weather.
*Dehumidifiers are classified by CFM, or Cubic Feet per Minute, which is a measure of airflow.  Once you've determined the ACH you need, multiply the ACH by the number of cubic feet in the area you need dehumidified.  Then, divide by 60 to come to the CFM.


  • Capacity and area of coverage – As mentioned earlier, the size of a dehumidifier is directly related to its processing capacity, usually measured in how much moisture it can extract in 24 hours. The larger the dehumidifier, the better it will do its job against a large area. The following information, from AHAM, can help you find the capacity you need:


Association of Home Appliance Manufacturers Dehumidifier Selection Guide


The numbers indicated are the Pints per 24 Hours, often called PPD



                           Square Footage


Area Feel







Moderately Damp: Area feels moist or has an odor













  Very Damp: Area usually feels damp or has a prominent odor













Wet: Area feels wet or seepage is visible



















Extremely Wet: Floors, walls, or ceilings are wet









  • Desiccant vs. Mechanical – Dehumidifiers are categorized into two types based on how they extract moisture from the air. Desiccant is a relatively smaller model and doesn’t use compressors. Instead, it works by exposing a drying substance to the air. The desiccant models, however, are best for light humidity and for areas with relatively low temperatures. Mechanical units, on the other hand, are equipped with both cooling and heating coils. The cooling coils are responsible for triggering the process of condensation (which extracts moisture), while the heating coils warm up dry air as it is pumped back into the room. Mechanical dehumidifiers are best used for medium to heavier humidity.


  • HumidistatEssentially a thermostat for your dehumidifier; this feature allows you to set your desired humidity level and leave the unit working with minimal supervision. Some dehumidifiers may also be able to shut off automatically when the tank is full.
    Sunpentown SD-72PE Dehumidifier


  • Anti-Frost Sensors: Frost can accumulate at operating temperatures as low as a few degrees below room temperature. Anti-frost sensors are especially valuable if you live up North.


  • Storage tanks and continuous drainage system – With a hose attached to the unit, you can eliminate the need to regularly remove the collected water. The alternative, however, is to use a storage tank. Intuitively, lower tank capacity will require more emptying.


  • Easily washable air filters – No matter how clean the area, dust will always collect within the air filter. Buildup can inhibit performance, so units with removable and washable filters will simplify this maintenance.


  • Price and brand – In addition to these factors, be sure to read reviews to gain insight into people’s experiences. We do not push one brand over another, as every manufacturer has its advantages and drawbacks. We will also be happy to answer any questions regarding what’s right for you!

By: Eugene Ravitsky

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