Top 5 Best Crawl Space Dehumidifiers (2023 Review)

After being a home inspector for several years, I have seen a lot of crawl spaces with moisture problems, wood damage, and mold growth.

High humidity in a crawlspace can cause mold issues, damaged insulation, pest intrusions, foundation problems, and other issues. Installing a dehumidifier in a sealed crawl space can help avoid a lot of problems, and that's why I made this list for the public.

Below is a shortlist of of the best crawl space dehumidifiers, but keep reading to see our buyer's guide on how to pick the best one. Let's get started!

5 Best Dehumidifiers For Crawl Spaces

1. AprilAire Dehumidifier Pro E100 Energy Star Pro (Best Overall) 
2. AlorAir Sentinel HD55 Auto Defrosting Dehumidifier (Best Budget)
3. BaseAire AirWerx55 Commercial Dehumidifier For Basements (Best Portable)
4. Dri-Eaz Revolution LGR Industrial Dehumidifier (Best With Pump)
5. Waykar 155-Pints Dehumidifier For Crawl Spaces (Best Industrial)

What Are Permanent Dehumidifiers For Crawlspaces?

A crawl space dehumidifier is a home appliance that automatically controls humidity levels and drains water to the outside.

These dehumidifiers tend to be more rugged than your average dehumidifier and can remove up to around 7-14 gallons of water per day. They are also typically rated to be able to withstand extreme heat and cold that may happen when exposed to outdoor air.

Unlike portable indoor dehumidifiers, these rugged humidifiers will drain the water (condensate) to the outside or to a drain automatically. It isn't hard to imagine that it would be a major pain in the neck if homeowners had to go into the crawl space each day to drain the tank. Many under house dehumidifiers have external or built-in condensate pumps which kick on when the float switch is activated.

Crawl space dehumidifiers are considered permanent installations and are installed on a level platform such as concrete block or they can be hanging from straps.

Read Also >> What Is The Building Code For Crawl Spaces?

How To Pick The Best Under House Dehumidifier?

When choosing a crawl space dehumidifier, homeowners should consider several different factors.

Coverage Area

The coverage area is the manufacturer's recommendation for how large of a space the dehumidifier can handle.

Typical coverage areas for these dehumidifiers are in the 3,000 square feet to 7,500 square feet range. It is essential to make sure that the dehumidifier can handle your crawl space size so you should have a rough idea of the floor area dimensions.

Access Door Size

Crawl spaces are notoriously tight spaces. And if the crawl space access door is too small for the dehumidifier — you won't even be able to get it inside.

Likewise, if the height of the dehumidifier (including any platform or block) is too tall and hits the floor joists, that is a problem. Just make sure the dimensions of the dehumidifier is suitable for your crawl space prior to purchasing it.

Condensate Pump

Depending on the crawl space, homeowners may need to purchase a separate condensate pump for the dehumidifier. If the exterior ground (around the home foundation) is higher than the floor in the crawl space, you won't be able to drain it to the outside. 

And if you don't have a sump pump in the crawlspace to drain it to, you will have to install a pump to carry it to the exterior or some other drain. Some manufacturers also may require a particular type of pump that works with their dehumidifier, so verify compatibility before purchase.

Some dehumidifiers have built-in condensate pumps. A problem with built-in pumps is that if it breaks, it can be major hassle to replace.

Read Also >> What Are The Best Condensate Pumps?

PPD Ratings

The PPD rating for dehumidifiers stands for pints per day and it will tell you how much water it can remove in a 24-hour period.

The most trustworthy PPD rating falls under the AHAM standard. AHAM stands for the Association of Home Appliance Manufacturers and this rating requires that the dehumidifier be tested at 80°F temperature and 60% relative humidity. Most dehumidifiers for crawlspaces are rated at 50-PPD and all the way up to 150-PPD.

Defrosting System And Temperature Rating

A defrosting system built into a dehumidifier is a great feature if your area experiences freezing temperatures.

If the crawl space gets very cold, the condensing coils can freeze over and damage the unit. For dehumidifiers with defrost systems, they can usually handle temperatures as low as 20°F to 35°F but you should check with the manufacturer.

Some crawl space dehumidifiers will even keep running while the defrost system is activated so you don't lose performance. Other dehumidifiers will shutoff automatically once the defrost cycle has begun.

Noise Level of Dehumidifier

The noise level of your dehumidifier can be an issue since it is close to the first floor of the home.

Small dehumidifiers tend to run at only 30-45 decibels, but larger units can be much louder at 55-100 decibels. If you are concerned about noise, we recommend checking with the manufacturer for a decibel rating as well as reading customer reviews.

How you install the dehumidifier can also impact the noise level. Make sure that the platform is solid and level and you may also want to add some platform padding.

Cost To Run And Longevity

Homeowners should consider the energy efficiency of their dehumidifier of choice and how much it will cost to run. Energy Star rated dehumidifiers will use at least 15% less energy than comparable units. But the longevity or lifespan of the dehumidifier can have a bigger impact on your wallet.

Since crawl spaces tend to be harsh environments, dehumidifiers breaking down is a common issue among homeowners. For cheaper models, dehumidifiers frequently only last 12-24 months. A high quality dehumidifier should last much longer than that, and that is why I usually recommend AprilAire.

Digital Humidistat

A humidistat will automatically turn the dehumidifier on and off in order to reach a target humidity level.

Typically there is a control panel on the side of the unit with up and down arrows so you can pick which humidity level you prefer.

Most homeowners should set the humidistat to between 50% and 60% in order to minimize the chances for mold growth and wood damage. Some crawl space dehumidifiers even have optional remote controls so that you can adjust the humidity level without having to go into the crawl space.

Filtration

Virtually all dehumidifiers have a filtration system to prevent damage to the unit. The filter system may be just one filter, or it may have a 2-3 filter layer. We recommend that homeowners find out if the filter is washable or if it will have to be replaced regularly.

Since most crawl spaces are a hassle to get into, homeowners shouldn't buy a dehumidifier that has to have regular filter changes. Cleaning the filter at least every 6-months is a common requirement.

How To Install A Dehumidifier For Crawl Space?

Air Sealed From Exterior

Dehumidifiers should only be installed in the crawl space if it is sealed from the exterior. There is no point in installing a dehumidifier if it constantly brings in moist outdoor air — it is a losing battle.

The only exception is if the dehumidifier is connected by ductwork to the home or the HVAC system. In such a case, the purpose of the dehumidifier is to remove humidity from the living space and not the crawlspace.

Central Location

Ideally, an under house dehumidifier should be located in the center of the crawl space. It is essential to keep the dehumidifier away from the crawl space door or any other area that may bring in exterior air.

If a central location doesn't work, then the dehumidifier should be placed so that the intake is closer to the foundation wall — and so it exhausts to the center of the crawlspace.

Hanging From Joists

One common installation of crawl space dehumidifiers is to hang it by straps from the joists. If your crawl space has room, hanging it by straps is a great option.

Not only does this protect the dehumidifier from water damage and flooding events, but it will also create more efficient drainage of the condensate. With the extra height, you may not even need a condensate pump, and it will also give you more room for storage or servicing.

Installed On Floor With Base

Crawl space dehumidifiers are commonly installed on the floor.

There should be a thick platform or two blocks for the dehumidifier to rest on such as 4-6" thick masonry blocks, bricks, or wood. It is important to make sure the base is secure and level.

There are also adjustable legs underneath the dehumidifier which you will have to adjust to make sure it is level.

Drain Line

The dehumidifier drain line will automatically funnel the condensate collected to the outside of the home (or to a floor drain). Depending on the type of drain line, your unit may require a p-trap or even a loop in the line.

Also, if gravity will not be able to drain the condensate to the exterior by itself, then you will need to install a condensate pump onto the side of the dehumidifier.

Our Reviews of the Best Crawl Space Dehumidifiers