Using a dehumidifier is your first line of prevention and defense in the fight against high humidity conditions around your home. These appliances work to lower a space’s overall humidity level by removing excess moisture and restoring balanced humidity. Maintaining a balanced humidity prevents mold growth, eliminates uncomfortable muggy conditions, and protects your home and valuables from damage.
Dehumidifiers are available in a variety of sizes and moisture removal capacities, and many models have upgraded features that make setup and use easy. In fact, the hardest part may be choosing the right dehumidifier for you. Fortunately, we can help. This article will guide you through the most important considerations you’ll have when shopping for a dehumidifier for your home, office, workplace, or other space. Read on to learn everything you need to know about choosing a dehumidifier.
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Why Use A Dehumidifier
In the simplest terms, dehumidifiers are used to lower the humidity level in a space. Sometimes lowering the humidity in your space is necessary in order to create a more comfortable indoors that’s free of clammy-feeling air, muggy conditions, and unhealthy mold growth. Typically, an indoor humidity level of 60% or higher is considered high. So, to create the healthiest and most comfortable indoor environment, we recommend maintaining a humidity level of between 30 and 50%.
Other than the main mission of lowering your humidity, there are other reasons why you might want to use a dehumidifier.
- Preventing Mold and Mildew Growth – Maintaining a healthier humidity level overtime helps stop a mold or mildew problem before it happens. Mold and mildew spores thrive and reproduce in hot, humid conditions above 60%. Basements, bathrooms, and kitchens, in particular, are three areas that are susceptible to mold infestations. Running a dehumidifier regularly in these spots can help keep them dry and mold-free.
- Managing Your Allergies – High humidity can intensify common household allergy triggers like dust mites, mold spores, and airborne bacteria, all of which can grow and reproduce rapidly in humid conditions. Keeping humidity below 60% makes your space less hospitable to these allergy triggers and helps you better manage your allergy symptoms.
- Pest Control – Like common household allergens, pests such as cockroaches, spiders, silverfish, and centipedes crave a moist environment. Maintaining a drier space repels these annoying critters and keeps them out of your home for good.
- Supplement Your Air Conditioner - Feeling cool in your home requires two things: cool air and dry air. Using a dehumidifier to supplement your central air conditioner keeps the air dry and frees your AC from working overtime to try to cool your humid space.
- Maintain the Structural Integrity of Your Home - Excess moisture, particularly in your crawl space or basement, can lead to infrastructure damage including rotting support beams, buckling floorboards, and damage to hardwood floors. Keeping the humidity level balanced in these areas can prevent costly repairs.
Ideal Spots for a Dehumidifier
Dehumidifiers are great solutions for a variety of areas in your home, from your kitchen to your basement or garage. Here is a list of common areas where you might use a dehumidifier:
- Crawl spaces
- Kitchens, bathrooms, and laundry rooms
- Garages and workshops
- Spa and indoor pool areas
- Warehouses and other industrial/commercial spaces
- Water-damaged areas
How Dehumidifiers Work
The vast majority of the portable dehumidifiers on the market today use a refrigeration system to condense moisture out of the air and lower the humidity. As a dehumidifier operates, humid air is drawn into the dehumidifier through an air inlet using the force created by an internal compressor and fan. The air is propelled over a series of cool condenser coils that pull out excess moisture and condense it into the dehumidifier's reservoir. Once this process is complete, the now-dried air is reheated and propelled back out into your room through an air outlet. Collected moisture remains in the water reservoir until you empty it or it is automatically drained via a connected hose. This process continues for as long as you use the dehumidifier, gradually lowering the humidity level in the space and creating drier conditions. Most residential and commercial/industrial dehumidifiers operate in this way.
Which Type of Dehumidifier Do You Need?
Dehumidifiers are available in 2 main types: residential and commercial/industrial models.
Residential dehumidifiers are portable, self-contained appliances that reduce humidity in small to large indoor spaces. These models are available in small, medium, and large moisture removal capacities and typically have lots of convenience features that simplify daily use. As you shop, you might notice that most residential dehumidifiers have electronic control panels, multiple fan speeds, casters, onboard humidistats, water buckets, and may be Energy Star-qualified. These are some of the more common features found on residential models. Residential dehumidifiers work well for everyday dehumidifying tasks around the house and some will be effective when used in larger dehumidifying jobs in a basement, for example.
Whole House Dehumidifiers
Whole house dehumidifiers are an option if you're looking to keep your entire home or a large office space dry and comfortable. Ducted whole house dehumidifiers install directly onto your HVAC system and dehumidify the air as it's cooled. Dry, cool air is then distributed throughout all the rooms of your home through your ductwork. These models are ideal if you're looking to dehumidify houses that are 1,500 square feet and up. It's usually best to have them installed by a qualified HVAC contractor.
Standalone whole house dehumidifiers are portable yet large enough to dehumidify a single floor of your home. Like portable residential models, these units are "plug and go" units that are easy to setup and operate. But it's important to place them in a centralized location in the treatment space for the most effective dehumidifying.
Commercial/industrial dehumidifiers are larger and heavier-duty units that are built for more unforgiving dehumidifying jobs. These models typically have moisture removal capacities that are much larger than residential dehumidifiers and housing that is constructed with rugged, all-weather materials to withstand extreme conditions. Other common features of these models include low-temperature operation, internal condensate pumps, loss of power protection, and simplified controls. You might use an industrial dehumidifier to help remove moisture in a flood-damaged space or to control humidity in an indoor pool area, for example. Some light industrial models are also more efficient choices for residential basements and crawl spaces.
Desiccant dehumidifiers are commercial/industrial dehumidifiers that don't use refrigeration systems or compressors and coils to condense moisture out of the air. These dehumidifiers lower humidity through a process called adsorption. Air is drawn into the dehumidifier where it passes over a rotating wheel impregnated with silica gel. As air passes over this wheel, humidity is absorbed into the silica gel before leaving the dehumidifier as warm dry air. No water is collected or drained out. Desiccant dehumidifiers are especially popular for low-temperature dehumidifying.
Choosing the Right Size Dehumidifier
A dehumidifier's size is determined by its total capacity to remove moisture. Capacity is rated in pints of moisture removed per day, or 24-hour period. So, for example, when you see a "30-pint dehumidifier," you're looking at a model that is rated to remove 30 pints of moisture total per day. A dehumidifier's capacity loosely indicates how large of a space it will cover in square feet. Therefore, if you know the square footage of the area you'd like to dehumidify, you can get a loose idea of the capacity you will need.
You'll also want to consider room conditions when choosing a size of unit. Ask yourself "how damp is my space?" If it's only a little damp, you can probably stick with the rated capacity for your square footage. If it's pretty damp, you'll need to choose a unit with a little more capacity. If you're dealing with an extremely wet space, you'll definitely need a large capacity unit.
To help simplify your choice in size, consult our handy sizing chart below:
Get more detailed information on choosing a size of dehumidifier in our article How To Choose the Right Size Dehumidifier.
Capacity at AHAM vs. Capacity at Saturation
Dehumidifier manufacturers may rate the moisture removal capacities of their dehumidifiers in different testing conditions. One manufacturer may assign a daily moisture removal capacity to a unit after testing it in AHAM conditions or in saturation conditions.
- AHAM conditions are average humidity conditions of 60% humidity, 80 degrees F. These testing conditions are recommended by the Association of Home Appliance Manufacturers (AHAM) in order to ensure a more accurate expectation for how a unit will perform in the vast majority of spaces, which tend to have average humidity levels most of the time.
- Saturation conditions are more extreme humidity conditions of 100% humidity, regardless of the temperature. Manufacturers use these testing conditions to measure the maximum amount of moisture a dehumidifier can remove per day.
As you're scanning the capacities of various dehumidifiers, it's important to think about the testing conditions each model might have been rated in. If you're looking at 2 models and one model was rated at saturation while the other at AHAM, for example, you won't be making a sound comparison. A dehumidifier that's able to remove 70 pints of water in saturation conditions (100% humidity) is going to remove less moisture in AHAM conditions (60% humidity); it would remove roughly half that amount. This is because a dehumidifier removes less water in drier air than in more humid conditions. Be sure to keep testing conditions in mind when you're evaluating models. If your space has very damp conditions, look for a dehumidifier that's tested at AHAM. It will be more robust than a model rated at saturation.
Draining Your Dehumidifier
Dehumidifiers that use refrigeration systems to condense moisture have to get rid of the collected moisture somehow. This is where draining comes in. There are 3 main methods of draining a dehumidifier and most models can be configured for at least 2 of these methods. That gives you more flexibility to choose the method that works well for you.
- Empty the Water Reservoir - The easiest way to remove collected moisture is by emptying a dehumidifier's water reservoir if it has one. Moisture collects in the unit's reservoir until it reaches capacity. You'll then remove the reservoir and empty it into a sink or another location. Most dehumidifier reservoirs are designed like drawers that you'll slide out with ease. Some also have handles to make them easy to carry back and forth for emptying.
- Gravity Drain - Most dehumidifiers also have a gravity draining hose port integrated into the design. This allows you to attach a hose, either a standard garden hose or one that's included with the dehumidifier, and let the unit drain water out automatically. For this method, you'll need to angle the hose downward and let gravity do the work. If needed, you can elevate the dehumidifier to help the process along. Route the drain hose to a nearby floor drain or another suitable location.
- Internal Condensate Pump - Some dehumidifiers have an internal condensate pump that is designed to pump moisture out automatically. This method is ideal if you'd prefer to pump moisture vertically to a sink or outside a window, for example. All you have to do is attach your hose to the pump port, route the hose to your preferred location, and let the pump do the work.
External Condensate Pumps
All dehumidifiers can be used with an external condensate pump so long as they are equipped to gravity drain as well. This is a special accessory that works exactly like an internal condensate pump, pumping moisture out of the water reservoir. To use, you'll attach a hose from the gravity drain port on the dehumidifier to the pump. Then, you'll route another hose from the pump to your preferred draining location.
Features To Look For
Nearly all residential and commercial/industrial dehumidifiers have added features that add convenience to your life and help the unit best fit your needs. Some features are more popular than others, depending on where you are using your dehumidifier. Below we'll break down the most popular features for residential and commercial/industrial applications.
Popular Features for Residential Dehumidifying
- Automatic Humidistat - A humidistat automatically maintains your desired level of humidity by triggering the dehumidifier to run only when needed. Helps energy savings too!
- Electronic Controls - Electronic or digital controls let you set a precise humidity level for accurate humidity control.
- Programmable Timer - Program startup and shutoff times based on your needs.
- Various Operating Modes and Speeds - Choose from multiple speeds and modes to find the right level of dehumidification for your needs.
- Casters and Handles - Casters and carrying handles aid in portability.
- Automatic Restart - Loss of power protection automatically restarts a dehumidifier in the event of a power failure. Great for basements!
- Low Temperature Operation - Most residential dehumidifiers operate successfully down to 41 degrees F. Look for this feature if you're using your unit in a cooler crawl space or basement.
- Automatic Defrost - In cold temperatures, automatic defrost helps keep your unit operational by defrosting any ice buildup to reduce downtime.
- Air Filter - Most household dehumidifiers have a washable air filter that traps allergens and particles and protects the unit's inner components from damage caused by debris.
Popular Features for Commercial/Industrial Dehumidifying
Low temperature operation, an automatic defrost system, and automatic restart are ideal features for commercial/industrial dehumidifying as well. Look for the below features too.
- Rugged Housing - Rugged, weatherproof housing stands up in extreme dehumidifying conditions.
- Internal Condensate Pump - Most commercial/industrial dehumidifiers have pumps instead of water reservoirs since they remove larger amounts of moisture.
- Advanced Air Filtration - Look for more advanced air filters on these dehumidifiers. They will help capture fine particles and debris and protect sensitive compressors from damage.
- Long Power Cord - A longer power cord lets you dehumidify multiple spots while still using a single outlet.
- Large Wheels and Handle - Large, smooth-rolling wheels and a heavy-duty handle make it easy to load a dehumidifier on and off a truck.
- Hour Meter - Hour meters track the number of hours a unit has been in service.
A lot of our customers wonder how much noise a dehumidifier will make. Keep in mind that the vast majority of dehumidifiers, especially those with compressors and fans, work by physically moving air through them. This process makes noise. However, the noise level varies from model to model. Some models are advertised as having "quiet operation." With these models, manufacturers have taken certain steps to reduce noise by insulating the fan or using a smoother-running fan, for example.
Dehumidifier noise level is measured in decibels (dB). A maximum dB rating of 40 to 50 dB is about average for dehumidifiers, which is comfortable to talk over, but you will hear it. How sensitive you are to the noise will, of course, largely depend on where you are placing it. You are less likely to hear your unit if you are using it in a basement while you are upstairs, for example.
Ducting Your Dehumidifier
Large-capacity dehumidifiers usually allow ducting, including larger residential and industrial/commercial dehumidifiers as well as ducted whole house dehumidifiers. This means you can integrate the system into your existing ducts and have dehumidified air flow back and forth through your ductwork. This is very helpful if you plan to:
- Duct multiple rooms and dehumidify them all at once.
- Install a whole house dehumidifier next to your HVAC system and duct it to dehumidify your whole home.
- Place the dehumidifier in a hidden location and duct it to deliver dehumidified air to another room or multiple rooms outside the dehumidifier's location.
- Run ducting throughout a crawl space to create steady air circulation to aid dehumidification.
Of course, there are other ducting applications as well. If you have questions about whether or not ducting would work in your application, feel free to call our product experts at (800) 934-9194.
Energy Efficiency and Cost of Operation
Today's dehumidifiers have come a long way in terms of efficiency. Models are now built with more efficient compressors and fans, and many of them are qualified under the Energy Star program. There are 2 efficiency indicators you should be evaluating when you are shopping for an energy efficient dehumidifier. These are:
- Energy Star - Dehumidifiers that are Energy Star-qualified have been evaluated and tested to Energy Star's rigorous efficiency standards. These models remove the same amount if not more moisture than a similarly sized conventional model, but use 15% less energy. They're also constructed with more efficient refrigeration coils, compressors, and fans to help them use less energy when removing moisture.
- Energy Factor - A dehumidifier's energy factor is a measure of efficiency that is determined by how many liters of water a unit removes per kilowatt-hour of electricity (L/kWh). In general, a higher energy factor means a more energy efficient dehumidifier. Look for a unit's energy factor as you browse a dehumidifier's specifications.
- Estimating Operating Costs - Estimating a dehumidifier's running costs can help you figure its monthly, daily, and even hourly operating cost and see if it fits in your budget. You'll do this by determining the kilowatts per hour (kWh) used when the dehumidifier is running. There's an easy formula for figuring kWh. Simply multiply the unit's wattage by the number of hours you plan to use it per day and divide that number by 1,000. The result is your daily kilowatt-hour consumption. You can multiply this figure by your electricity rate to get an estimated daily operating cost and do further simple math to figure hourly, monthly, and annual operating costs.
A dehumidifier may have a fan that runs continuously or only when the system is actively dehumidifying. In recent years, a debate has heated up over which fan design fuels a more efficient dehumidifier. Here's the lowdown on each option:
- Fan Runs Continuously - When a dehumidifier fan runs continuously, the fan is always on whether the compressor is running or not. The manufacturers of these models theorize that a continuously-running fan helps move air continuously past the humidity sensor (if equipped), so that the dehumidifier gauges a more accurate humidity level in the room. This helps the unit adjust fan speed and maintain your desired humidity level consistently. In addition, a continuously running fan helps redistribute dehumidified air more effectively throughout your room for even coverage. Some people might be concerned about the amount of energy consumed by the running fan. But this shouldn't be too much of a concern since a dehumidifier fan consumes only about as much energy as a light bulb on average.
- Fan Runs Only When Dehumidifying - When a dehumidifier's fan runs only when dehumidifying, the fan cycles off when the compressor turns off. The fan may cycle off immediately with the compressor or after a short few-minute delay after the compressor shuts off. The manufacturers of these models theorize that a continually running fan saves energy and helps make the dehumidifier more efficient. But again, the energy savings will be minimal since dehumidifier fans are not considered excessive energy consumers.
Which option is truly more efficient? We theorize that dehumidifiers with fans that run only when dehumidifying only save a small amount of energy, about as much as a light bulb would use. It's actually a dehumidifier's compressor that uses the most amounts of energy and power. For the most effective and wider reaching dehumidifying, we like a dehumidifier that has a continuous running fan. These models will more accurately sense your room's humidity level and adjust operation accordingly, so you'll get the best results and you'll stay within your energy budget.
Special Power Requirements
Most dehumidifiers are designed to be plugged into a standard household outlet at 110-120 voltage (V). Certain larger industrial dehumidifiers may be rated for a 220-240 V outlet or different. Whole house dehumidifiers are typically hardwired into your electrical system. Before you purchase a dehumidifier, be sure to confirm that its voltage power requirements are ideal for your space.
The best way to make sure you get the most out of your dehumidifier investment is to take the time to perform recommended the maintenance. When you purchase your dehumidifier and begin using it, be sure to review the manufacturer's maintenance tips in the user manual. These may include:
- Cleaning and/or replacing air filters as needed
- Draining the unit before storage season
- Instructions for cleaning your dehumidifier and water reservoir
- Troubleshooting recommendations
- Contact information for warranty service
Dehumidifiers can last anywhere from 3 to 15 years. Performing the recommended maintenance and keeping your unit in good condition helps lengthen the operating lifespan. Learn more about how to take care of your dehumidifier in our article Maintaining Your Dehumidifier.
Still Have Questions?
We know choosing a dehumidifier isn't an easy decision. To learn more about dehumidifiers, visit our Dehumidifier Knowledge Center. Not sure what's best for you? We can take the guesswork out of decision-making. Call us at 800-934-9194. We want to help make your indoors healthy and comfortable.