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High humidity in a crawl space can lead to a whole slew of issues. Mold, mildew, and wood rot are some of the problems that moisture in a crawl space can lead to. Using a dehumidifier in your crawl space can help remedy those issues.
In this article, I’ll take a look at a few crawl space dehumidifiers on the market today. I’ll go over their pros and cons, as well as considerations that need to be made before purchasing.
I’ll also discuss where you should place your crawl space dehumidifier, and give an outline of how to install your crawl space dehumidifier.
Best Overall Crawl Space Dehumidifier
Aprilaire’s dehumidifiers are the industry standard for crawl spaces and whole homes. They are so good, I’ve even seen them used in commercial applications.
The Aprilaire 1820 is a 70-pint dehumidifier. This means that it is capable of removing up to 70 pints of water every day. In terms of area coverage, they are good for around 2,800 square feet.
The Aprilaire 1820 is purpose-built for crawl spaces. It is super easy to install, and the included collars make attaching flex duct a breeze.
When deciding where to place this dehumidifier, keep in mind that the filter access is on the side of the unit. So make sure you leave some space on the side so you can access the filter. The filter in this unit is washable, so you won’t need to buy disposable air filters over and over again.
While we’re on the topic of air filters, be sure to check the air filter at least every 6 months. Check it more often if your crawl space is unfinished. Aprilaire’s website says “once a year filter cleaning”, but that is quite a stretch– especially for dirty crawl spaces.
The one thing that this dehumidifier doesn’t have is a built-in condensate pump. That’s no problem if your condensate drain is below the unit. But you’ll need a pump if you want to move condensate upwards.
Easiest to Maintain Crawl Space Dehumidifier
The AlorAir HDi90 dehumidifier is a 90-pint dehumidifier that is rated for 2,600 square feet. It’s made to operate in a variety of conditions and can dehumidify the air that’s down to near-freezing temperatures.
My favorite part about this dehumidifier is its built-in condensate pump. Using a condensate pump is necessary if you need to drain your condensate upwards. You’ll also need a condensate pump if you want to set up your drain a long distance from your unit.
While we’re talking about draining, the HDi90 comes with a 5-meter drain hose. By using the drain hose, you’ll be able to move condensate in whichever direction you want.
One great part about AlorAir’s dehumidifiers is that they have a spare parts list. Most people would overlook this. But for anyone who deals with lots of mechanical equipment, a spare parts list is a huge deal.
On any piece of equipment, something is bound to wear out after a few years of use. With a spare parts list, you’ll always be able to figure out what the ordering information is for something that breaks. Better yet, they have a YouTube channel that shows you how to do common repairs on the dehumidifier.
If you need to duct this dehumidifier, the supply vent has a duct collar for easy duct attachment. The return vent does not have a duct collar. However, a return duct kit is available as a separate purchase if you need one.
The filter access to this dehumidifier is located behind the return grille. There are two filters: a mesh pre-filter, and a G3 final filter. Both of these filters are washable with soap and water. There is even a MERV-8 filter available separately if you need extra-clean air in your crawl space.
One cool thing about this dehumidifier is that the supply vent is on the side of the unit. This means that you can install it close to a wall and still get good airflow coverage.
Best Portable Crawl Space Dehumidifier
AlorAir Storm LGR Extreme is a rugged dehumidifier that’s built for mobile use. It is designed to be easy to set up and transport, so you can deploy it wherever you need it.
The Storm LGR Extreme is rated for 85 pints and 2,300 square feet. It also includes a built-in condensate pump so you can direct condensate out of the area that you’re using it in.
This dehumidifier excels at removing moisture in areas that get wet for short periods of time– such as a basement after a rainstorm, or if an area in your home is prone to flooding. But I wouldn’t recommend this dehumidifier for a permanent installation since it’s not designed for that.
The filter on this dehumidifier is a metal mesh filter. It slides out from behind the return grille. You can wash the filter with water and then replace it after it dries.
My favorite part about this dehumidifier is that from top to bottom, it is built tough. If you need to transport a dehumidifier from one place to another, then this is absolutely the dehumidifier for that.
In the event that something does break on this dehumidifier, replacing parts is a breeze. The Storm LGR Extreme is designed to be user-serviceable. AlorAir even has a YouTube playlist with instructional videos on how to do common maintenance tasks.
Best Budget Crawl Space Dehumidifier
The Waykar 155 Pint Dehumidifier is designed to dehumidify large open areas. It has all the standard features of a dehumidifier, including a humidistat, timer, and defrost cycle.
My favorite part about this dehumidifier is that it has an external humidity sensor. The humidity sensor has a 16’ cord and plugs into the unit. Once the sensor is plugged into the unit, you can place it wherever you need to. This means that you can have the unit control itself to the humidity in a space that it’s not physically located in.
One thing about this dehumidifier is that it does not include a built-in condensate pump. So you’ll need to direct the condensate hose downward or install an external condensate pump.
While the unit is priced for those on a budget, it comes with its drawbacks. First, the documentation is lacking. The user manual is obviously written by someone whose first language is not English. There are spelling errors, and some statements are hard to understand.
Additionally, the user manual is very short and not helpful for diagnosing or troubleshooting issues. This might be a problem if you’re looking for a dehumidifier that will last you a long time.
There is also no parts list available, so you’ll need to know exactly what you’re looking for if this unit ever gives you problems.
With all its drawbacks, the Waykar 155 Pint Dehumidifier gets the job done for those on a budget. If you’re looking for a no-frills dehumidifier for your crawl space, then it is a good choice.
Crawl space dehumidifier comparison table
70 pints per day
90 pints per day
85 pints per day
155 pints per day
25" x 12.5" x 12.5"
23.2" x 15.2" x 17.7"
22.8" x 13.7" x 17.3"
25.6" x 18.1" x 14.1"
Spare parts list
Portable for temporary applications
External humidity sensor
Can you use a regular dehumidifier in a crawl space?
Using a regular dehumidifier in a crawl space is not recommended for the following reasons:
- Regular, portable dehumidifiers have a tank that needs to be emptied out. This means that you’ll be going down there to empty the tank on a regular basis. Depending on the size and humidity in your crawl space, it could need emptying every day!
- The size and form factor of regular dehumidifiers is not made for crawl space installation. Some houses have crawl spaces that are only two or three feet high. Most regular dehumidifiers are taller than that, so they won’t even fit in a crawl space. If you do manage to find a small portable dehumidifier, chances are that it doesn’t have enough capacity to dehumidify your entire crawl space.
- Large open crawl spaces require lots of airflow to dehumidify. While a regular portable dehumidifier is good at dehumidifying a single room, it will struggle to produce enough airflow to dehumidify an entire crawl space.
Where should you place a dehumidifier in a crawl space?
The placement of a dehumidifier in a crawl space is critical to how well it will perform. There are two main considerations when choosing a place for a dehumidifier in a crawl space: airflow and drainage.
Crawl space dehumidifier airflow
The first thing to take into account when selecting a place for your dehumidifier is airflow. You need to make sure that airflow won’t be blocked. This means that you need to keep your dehumidifier away from tight spaces such as corners.
You should try to separate the supply and return air vents of the dehumidifier as much as you can. If possible, place your dehumidifier on one side of your crawl space. Then run ductwork for your dehumidifier’s supply air to the other side of your crawl space.
Separating the supply and return vents creates a stream of airflow that encompasses the entire area of your crawl space. Having airflow cover your entire crawl space helps to ensure that you won’t have any stagnant humid areas.
Dehumidifier location in a large open crawl space
If your crawl space is large and open without many barriers, then you’ll want to ensure that you get proper airflow circulation.
Separating the supply and return ducts should be the first priority to ensure adequate airflow coverage.
Dehumidifier location in an L-shaped crawl space
If your crawl space is L-shaped, then you will need to direct airflow into the corner. This ensures that stagnant, humid air won’t get trapped in the corner while the rest of the space gets dehumidified.
Dehumidifier location in a divided crawl space
If your crawl space is divided or has a barrier, then you’ll need to direct airflow from one side of the barrier to the other. This ensures that airflow is circulated to both sides of the barrier.
If you go this route, be sure that the air has a return path back to the dehumidifier, as shown below.
Crawl space dehumidifier drainage
When placing your dehumidifier, keep in mind that you’ll need to find a place to pipe the condensate line to. Most people typically run the condensate line along one of the floor joists to the outside of the house.
It’s easiest to install a drain hose from the dehumidifier down and outside of the space. By doing this, you’re letting gravity do the work. But if you need to move the condensate upwards, then you’ll need a condensate pump.
A condensate pump is used to move condensate from your dehumidifier to wherever it needs to go- typically outside. Some dehumidifiers have a condensate pump built in. For most people, a condensate pump is recommended unless you’re absolutely certain that you’ll be able to drain your dehumidifier using gravity alone.
How to install a crawl space dehumidifier
Installing a crawl space dehumidifier takes quite a bit of know-how to do properly. Here is a general step-by-step list of instructions on how to install a dehumidifier in your crawl space:
- Place the dehumidifier. The dehumidifier should be positioned in a spot that allows for unobstructed airflow. Also, make sure that there is ample clearance around the dehumidifier for maintenance.
Most people will place their dehumidifier using one of two methods: Hang the dehumidifier from floor joists using straps, or set the dehumidifier on concrete blocks. Of these two methods, placing the dehumidifier on concrete blocks is the easier method.
- Install the ductwork. Most homes have large crawl spaces, so some amount of ductwork is needed for your dehumidifier. This helps to direct air across the entire crawl space area. For this purpose, flex duct works really well since it is easy to install.
- Install the condensate drain line. Since your dehumidifier will be removing moisture from the air, it needs a place to put all that water. This is where the condensate drain line comes into play. A good place to install the condensate drain line is to run it along one of the floor joists to the outside of your home.
Keep in mind that if your condensate drain line is higher than your dehumidifier, then you will need a condensate pump. The condensate pump is needed to push water up and out of your crawl space.
If your dehumidifier is higher than the location where your condensate drain line will discharge, then you won’t need a pump. You can just install your drain line at a slight downward angle so the condensate flows out.