Updated Jun. 05, 2024
Remove moisture to prevent mold, mildew and wood rot. We evaluated the top-rated picks to help you choose the right crawl space dehumidifier for your home.
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Crawl space moisture can create a whole slate of trouble in the often-unseen underside of a home. Standing water and vapor trapped inside the space can create ideal growing and living conditions for mold, mildew and pests—potentially causing poor indoor air quality, structure rot and a mess to clean up. Crawl space dehumidifiers, and a few other tools, help avoid all that.
A dehumidifier removes moisture from surrounding air by condensing the water out of it using refrigerated coils. Air conditioners work similarly to remove heat and water vapor from living space air for comfort. Likewise, basement dehumidifiers can be effective tools for helping prevent basement mold. However, while living space air conditioners and dehumidifiers perform well when conditioning indoor air, crawl space dehumidifiers must contend with additional challenges.
“When choosing a dehumidifier for a crawl space, look for a unit specifically designed for such environments,” says Josh Mitchell, HVAC and plumbing technician. “These dehumidifiers are typically more sturdy and capable of operating in colder temperatures compared to standard residential models.” He adds that a key feature to look for is a built-in hygrometer, which measures the humidity level, allowing the dehumidifier to operate automatically to maintain the desired humidity level as well as one with continuous drainage.
The potential for high moisture levels and the need to operate within a confined space means crawl space dehumidifiers must meet a higher calling. Choosing one for the task brings up several qualifying questions. To help you decide which is best for your situation, we’ve compiled this list of the best crawl space dehumidifiers.
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While it may not be necessary for a crawl space dehumidifier to look good, the Alorair Storm LGR Extreme does just that with its four available color options (yellow, blue, green and red). However, that’s not what makes it an excellent choice for protecting your crawl space. A wide operating temperature range from 33.8 to 104 degrees Fahrenheit, a nearly 20-foot power cord, low grain refrigerant (LGR) technology, the ability to remove up to 180 pints per day (PPD) of water and convenient memory restarting are a few qualities that do, though.
LGR is a method of cooling air more efficiently to help remove more water. The technology allows effective operation over a wider temperature range than non-LGR machines. Low-operating temps mean you can set the Storm LGR Extreme and forget it. The unit also features a Merv 8 filter, which traps most airborne particles larger than 3.0 microns (or roughly the size of the smallest mold spores).
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While protecting your home from mold and wood rot damage caused by water is no place to cut corners, you may not have to break the bank, either. The Sahauhy commercial dehumidifier packs substantial capabilities into a wallet-friendly price. You’ll only need to add a condensate pump if there’s no drain nearby.
With the ability to remove a maximum of 158 PPD of water when necessary, the machine easily pulls 74 PPD from the air under normal conditions. You can attach a duct to its side to vent its exhaust for even, more effective dehumidifying and potential removal of unpleasant gasses. Other features include a remote control with 26 feet of wire, a 10-foot drain hose, auto defrost and automatic memory restart.
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Psst! If you’re looking for something for smaller spaces, these best small dehumidifiers will come in handy.
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Alorair offers two versions of its Sentinel crawl space dehumidifier. The Alorair Sentinel HDi90 is our choice for the better of the two, because it includes an integrated condensate pump to remove water without the need to reach a drain using gravity. The product features an optional CAT5 wired remote control, an operating temperature range of 36 to 104 degrees Fahrenheit and a 210 cubic-feet-per-minute (CFM) air capacity to effectively dehumidify up to 2,600 square feet.
Understanding what dehumidifiers do helps explain what makes this one unique. Crawl space dehumidifiers are measured in part using two metrics. The first is the PPD of water that it can remove in a laboratory set to 80 degrees Fahrenheit and 60% humidity. The second, PPD at saturation, is the same measurement, but at 90 degrees Fahrenheit and 90% humidity. The Sentinel HDi90 rates at a whopping 90 PPD and 198 PPD, respectively.
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Water trouble can happen in small spaces, too. For homes with a smaller footprint and crawl space, the BaseAire Airwerx 35P is a smart choice. Don’t let the smaller size fool you—this little workhorse, measuring under 16 inches long, less than 1 foot tall and under 50 pounds, can remove up to 70 PPD of damaging moisture in up to 1,000 square feet and around 35 PPD under typical conditions.
The Airwerx 35P uses GLGR technology, which measures and uses absolute humidity to precisely adjust the environment’s water vapor level. The unit’s portable design houses a condensate pump that attaches to the included 19.6-foot drain hose for use almost anywhere. The only drawback is its filter’s low rating of Merv 1, which is great for airflow, but not for capturing airborne particles.
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In most homes, you can set up a crawl space dehumidifier, check on it occasionally and change the air filter. However, if your home has multiple, or limited access, crawl spaces, you may be looking for a unit that’s easy to move from place to place. At just 44 pounds, the Alorair Sentinel HD55S does the trick.
The HD55S is a self-draining dehumidifier that doesn’t come with a condensate pump. However, an optional corded remote control is available, and you can vent the exhaust outdoors with its duct connection. It’s adjustable feet make leveling easy and is one more convenient feature that makes this machine a handy tool for portable dehumidifying. The Sentinel’s reasonable price tag is a nice feature, as well.
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Some crawl spaces don’t require continuous dehumidification, but are still vulnerable to occasional water intrusion. In the case of flooding or other water emergencies in a crawl space, this B-Air commercial dehumidifier stands upright and ready on its pair of oversized wheels for easy transport and quick setup. Its 38-foot drain hose, condensate pump and 25-foot grounded power cord mean you can put it right where you need it.
Moving 325 CFM of air over its coils and pulling 7.36 amps of electrical power, the B-Air delivers enough power to remove up to 150 PPD of water from saturated air at temps of 33 to 100 degrees Fahrenheit. While the Vantage VG-1500 doesn’t have all the bells and whistles of traditional crawl space dehumidifiers, it does feature an easy-to-use control panel and solid customer reviews.
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Crawl space dehumidifiers work hard under tough conditions, but they have limitations. While they’re perfectly capable of helping to protect your home from water damage, other water extraction methods may be required if you need to deal with a flood or dry out a flooded basement carpet. However, if your crawl space requires dehumidification to mitigate a moisture problem, here are a few things to look for when deciding which is right for your home:
Deane Biermeier has over 30 years of experience in residential construction, contracting, remodeling, maintenance, and home repair. Throughout his time in the field, he’s dealt with a lot of crawlspaces and basements and knows how much damage excess moisture can cause. He’s an expert on what features to look for to find the best products for his customers.
We consulted with Josh Mitchell, a plumbing and HVAC technician who runs websites that help others solve their home repair problems. As the owner of Air Conditioner Lab and Plumbing Lab, Mitchell helped give more insight into why dehumidifiers can be important in a crawlspace and how to find the best option for you.
With a long history of helping you choose the best products in and around your home, it’s no surprise that Family Handyman also cares about the products under your home. However, our opinion matters little without thorough research. We examined as many machines as possible to help you choose the best crawl space dehumidifier for your needs. We rated them based on performance, features, reviews and standout qualities.
Crawl spaces vary in shape, size and configuration. Many of them have water issues, however, not every crawl space needs a dehumidifier. It’s a good idea to set one up only after the area is encapsulated against water and vapor penetration, venting to the outdoors is sealed and any mold or water damage is remediated.
“Installing a dehumidifier in your crawl space can be a worthwhile investment, especially if you’re experiencing issues with high humidity levels, mold growth, or musty odors,” adds Mitchell. “Excessive moisture in a crawl space can lead to structural damage over time, as well as contribute to poor indoor air quality in the living spaces above. A dehumidifier helps maintain a dry environment, protecting your home from these risks.”
The best crawl space dehumidifiers must meet unusually high demands. The first thing to take into consideration is the size of your crawlspace. The capacity of the dehumidifier should match or exceed the square footage of your crawlspace. A crawl space needs a dehumidifier that can run continuously, if necessary, drains itself with a pump or by gravity, is highly effective at controlling humidity and generally doesn’t need you to do much other than change its air filter occasionally.
Similar to how a whole-house fan cools your home if the venting is correct, a dehumidifier effectively dries out a crawl space under the right conditions. Removing the bulk of the water from the crawl space first is crucial for a dehumidifier to work well. Foundation drains, vapor barriers, vent seals and waterproofing are all effective methods of helping a dehumidifier do its job.
Dehumidifier size refers to how much water it can remove from the air under normal crawl space conditions. A machine rated to remove from 65 to 80 PPD is sufficient for most well-sealed, average-sized crawl spaces. Spaces under 1,000 square feet can get by with ratings from 30 to 50 PPD. A dehumidifier large enough to eliminate humidity in a vented or poorly sealed crawl space doesn’t exist.
Originally Published: March 26, 2024
