Crawl Space Dehumidifier Installation

If you need a dehumidifier for your crawl space, buying and installing it will not be as easy (or cheap) as a stand-alone dehumidifier. Where and how you set up your unit can affect its efficiency and effectiveness in controlling your indoor humidity and air quality. You want to make sure you’re getting the most out of your investment. 

Finding the right unit and installing it in your crawl space may seem like too daunting a task for you, and you can always consult an expert for the best solution. But if you want to try your hand at this, we’ll guide you with these general steps in crawl space dehumidifier installation.

If you’re ready, grab your tools and let’s go.

Why You Need a Crawl Space Dehumidifier

The crawl space in your house is especially prone to dampness due to its location and possible leaks or other water damage. High levels of humidity encourages mold and mildew growth. When mold starts growing in your crawl space, it can spread to your entire house through the vents. Touching mold or inhaling mold spores may cause allergic reactions, or allergy-induced asthma attacks and other respiratory conditions. 

Extreme dampness in your crawl space can also lead to structural damage in your house. Since most homeowners rarely check up on their crawl spaces, you may not notice that you have humidity problems until it’s too late. Watch out for some of these signs that you need a dehumidifier in your crawl space.

Musty odors are a common indication of mold or mildew growth. If you cannot find the source inside your house, it is most likely in your crawl space. Air rises from the crawl space and carries mold spores, dust, and other airborne particles. 

Additionally, if you have your HVAC system or other ductwork installed in the crawl space, then condensation may accumulate. Leaky pipes and other water damage can add even more humidity to the space. You may notice moisture on your windows or damp spots on the floor.

Creaking, sagging, or sloping floors may be a sign of structural damage caused by severe dampness in the crawl space. Excess moisture can lead to rotten wood and termite infestation. If you notice cracks in drywall and gaps between the floor and baseboard, this may also be signs of an underlying humidity problem. 

Crawl Space Dehumidifier Installation Guide

You have two options for installation. You can either hire a professional contractor or simply do it yourself. Now, we always recommend professional installation to make sure everything is done properly, but for handy homeowners with the right set of tools, this task may be a piece of cake. Professional installation may cost at least $500 up to $1,000, while a DIY job will  cost around $1,000 just for the tools you may not already have in your toolbox at home. Whichever you choose, the process follows more or less the same steps below.

Choose the Right Dehumidifier

When choosing a crawl space dehumidifier, some of the most important factors you must consider are the area and the level of dampness in the space. Manufacturers design compact, horizontal crawl space dehumidifiers for this purpose. Measure the dimensions of your space and make sure the dehumidifier you choose can fit perfectly with enough room to move around. Crawl space dehumidifier capacity ranges from 70 pints up to 200 pints per day. Look for signs of dampness or measure the exact levels of humidity to get the ideal pint capacity for your home.

Pick the Best Location

Dehumidifiers are usually placed in the middle or on one side of the room to maximize coverage, but finding the ideal location can be trickier for a crawl space unit. The best placement for a dehumidifier is always where the air can flow with no blockage. 

Keep in mind that high capacity dehumidifiers can be quite loud, so consider this before installing it near areas where noise would be inconvenient. You may also want to keep your dehumidifier easily accessible for regular cleaning and maintenance. Drainage is another factor to consider when finding the best location to install your dehumidifier.

Set Up Drainage

Most crawl space dehumidifiers feature continuous draining through a drain hose. One possible downside with this is you’ll need to have a floor drain nearby. Gravity drainage will only work if the unit is in a higher placement than the drain.

Alternatively, high capacity units may come with a built-in pump which automatically drains the condensate. This may be a necessary feature for crawl spaces without a floor drain. With an automatic pump you can have the drain hose run up to a window to release the water outside or to your sump pump. For dehumidifiers without this feature, you can purchase an external condensate pump. Dehumidifier brands like Aprilaire and Santa Fe also offer condensate pumps for specific models.

Set and Monitor the Humidity Level

Once your dehumidifier is all set up, you need to input your desired humidity level either on the control panel or with a remote humidistat. The ideal range for the average person is between 30% and 50% RH. Anything below 30% is considered too dry, and above 60% is too humid. If your crawl space gets too cold or you have any other specific needs, make sure your dehumidifier has the ability to perform as required.

Proper Maintenance of Crawl Space Dehumidifiers

Dehumidifiers for crawl spaces usually require little maintenance, but it causes no harm to take extra care for your appliance. The easiest way is to simply follow the manual. The manufacturer gives you all the specifications and instructions for installing, using, and maintaining the unit. Warranty information is also included.

For optimum results, find the best place to install your dehumidifier. Make sure the space is as tightly enclosed as you can make it. The more outside air is getting into the area, the harder the unit has to work. Most dehumidifiers work best in warm temperatures around 59-86°F, unless it’s specifically designed for colder conditions.

Dehumidifiers purify the air through filtration. This protects the machine and its components from dust, bacteria, and other allergens present in the air. For every model there is a recommended period after which the filter must be cleaned or replaced. More information and detailed instructions are found in the manual.

When the temperature drops to a nearly freezing level, check the coils for frost. Operating your dehumidifier in cool conditions may sometimes cause ice to build up inside the machine. This can compromise the unit’s performance and even cause permanent damage. Some models feature auto defrost. 

Best Crawl Space Dehumidifiers

Now that we’ve covered the installation process, if you’re want to know how to choose the best dehumidifier for a crawl space, check out our full article here. Three of our favorites are the Aprilaire 1820, the AlorAir Sentinel HDi90, and the Santa Fe Compact 70. Our complete article here covers how to approach choosing a crawl space dehumidifier, as well as why these models are some of our top picks.


Keeping your crawl space dry and insulated is important in maintaining a healthy home. Not only will this protect your property from mold or pest infestation but also ensure that you are breathing clean air. 

If you have existing water damage in your crawl space, remove standing water and fix any leaks to reduce dampness. To keep humidity away permanently, invest in a crawl space dehumidifier. A good dehumidifier can go a long way in preserving the structure of your house and improving the air quality. Once you find the right unit for your crawl space, it’s highly recommended to consult an expert when installing your dehumidifier to make sure it’s done properly.

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