It’s a safe bet that your home or business needs a crawl space dehumidifier. The very nature of a crawl space invites images of mud, soggy soil, slop and all the things that thrive in such conditions, and it’s not a good image. The best crawl space dehumidifiers can help. Let’s see how.
When foundation vents first came out, many moons ago, they were hailed as an amazing innovation, because they allowed fresh air to circulate beneath the house. But in recent years, that practice has come under criticism, because in humid parts of the country, humid air gets drawn into the crawl space when the vents are left open (and to some degree when they’re closed). That humid air from the crawl space then gets circulated throughout the house.
To combat that tendency, chances are, you need the best crawl space dehumidifier. But what kind is the best kind of crawl space dehumidifier? How big of a crawl space dehumidifier do you need? How much should you pay for a crawl space dehumidifier? What brand is the best brand of crawl space dehumidifier?
The following list should help you decide on the best crawl space dehumidifier.. Be sure to read the general guidelines at the end of the list to help you determine what’s the best crawl space dehumidifier for your home or business.
Top 8 Best Crawl Space Dehumidifiers
Best Feature: Works Well at Low Temperatures
The AlorAir Sentinel HD55 is a medium to large space dehumidifier, capable of treating the humidity in a 1300-sq ft area. It’s marketed primarily as a basement dehumidifier, but it can also be used in crawl spaces and other enclosures.
The dehumidifier comes with a humidistat (think of it as a thermostat, except it measures and responds to humidity levels) whose job is to monitor basement or crawl space and maintain a humidity level that you select. The unit goes from totally off to full operation when the humidity goes above that point (in most situations, that would be around 50% relative humidity).
The HD55 is rated at 55 pints per day (PPD) by the Association of Home Appliance Manufacturers (AHAM), an organization that publishes equilateral standards for home appliance performance. These standards are voluntarily contributed by its members, and represent a reasonable performance expectation when compared to other appliances in its class.
A crawl space is kind of an in-between area – not really exterior and not really interior – but temperature-wise, it’s exterior. And it can get pretty cold in there. One of the great advantages of the HD 55 is its Hot Gas Valve Defrosting System, which clears ice that may form on the coils down to 2° F.
The HD 55 can either be direct-vented (releasing air through a port) or ducted (connected to ductwork for release, either to the exterior or even to the HVAC system within the house). In order to connect to a duct system, a dehumidifier must have a strong enough fan to overcome the static pressure of the ductwork, and the HD 55 does. The HD 55’s 3.6-amp motor can move 130 CFM (Cubic Feet per Minute) of air.
That takes care of the air, but what about the water? The HD 55 uses a gravity-fed drain system. Water is expelled through a port at the bottom of the unit into a tube. Six feet of tubing is included. You can route the tubing to a french drain or allow it to drain onto the ground outside of the crawl space. Since it’s gravity-fed, the drain tube must run downhill.
A nice optional feature of this dehumidifier is the ability to use a remote control to adjust the dehumidifier’s settings. This can also be programmed to work with a smartphone via Wi-Fi. Sometimes, the best indicator of how much dehumidification is needed is how comfortable you feel. Being able to control that from your sofa, rather than run down to the crawl space is a real bonus.
It’s a pretty compact unit, measuring 19 x 12.2 x 13.3 inches. Access to the homeowner-serviceable sections of the dehumidifier is easy. Cleaning the coils regularly and cleaning/changing the filter when scheduled will not only keep the unit operating at peak efficiency, it will help ensure a long life for your investment.
If you’re looking for a higher capacity than 55 PPD, AlorAir also makes a 90 PPD Crawl Space Dehumidifier, which is just a higher capacity version of the 55 PPD model just discussed and it comes with a condensate pump (more on condensate pumps below).
Best Feature: Five Year Warranty
It’s not the prettiest home appliance you’ve ever seen, but, hey, it goes in the crawl space and your poker night buddies won’t ever see it. You’ll think it’s beautiful after you spent a few days enjoying dehumidified air, supplied by the Airwerx 55.
It produces 55 pints of water per day, cycles 130 CFM of air and treats 1300 square feet of crawl space. Plus, it’s built to last, with coated, stainless steel coils and fins, heavy steel cabinet and sturdy fittings.
Discharge air can be released back into the crawl space in a much drier state, or it can be connected to ductwork and released to the exterior or even incorporated with the HVAC ductwork and distributed throughout the house.
Water drainage is gravity-fed only. That’s no problem if you have a handy downhill run to a french drain or outlet to the exterior. If not, you’ll have to get a little creative. The unit ships with six feet of tubing, so you do have some length to work with*.
*An option well worth considering is a condensate pump. This pumps the water uphill, if necessary. See the section at the end of the dehumidifier recommendations for more information.
The Airwerx 55 can be operated via an optional remote for easy humidity settings. And as far as maintenance is concerned, they’ve made it as simple as possible, because, after all, grunging around in a crawl space is not a whole lot of fun.
One of the best warranties of any unit on our list is the five-year full warranty on the Airwerx 55. It’s applicable only to the original purchaser, who has to follow all the rules regarding installation, operation and maintenance. But five years is five years.
AirWerx also makes the AirWerx140X which is a 140 PPD capacity version of this same crawl space dehumidifier.
Best Feature: Excellent Efficiency (Especially for 85 PPD)
This is one thirsty dude, dude! The AlorAir LGR 85 is a commercial grade crawl space dehumidifier that wrings out 85 pints of water out the air every day. And that’s at AHAM standards, which are set up for conditions of 80 percent relative humidity. At full saturation (which, honestly, isn’t going to happen in your crawl space, but it’s worth discussing), it could draw 10-15% more water from the air. That is pretty impressive.
Another remarkable feature of this dehumidifier is that it does all that while only drawing 5.4 amps on standard house current. That’s good for your power bill and very green for the environment.
The unit is waterproof. Obviously, this is a good trait for a dehumidifier to have, but this is really waterproof. You can set the unit in a puddle and it will run. A rubber seal running around all the joints keeps the important stuff dry.
A feature with all of AlorAir’s top models is their epoxy-coated coils, sealed against damage, yet still able to function efficiently with heat transfer. Another feature common to AlorAir’s high-performing models is the HGV defrosting. This will melt ice that forms on the coils in cold weather. If you’ve ever had to melt ice off the crawl space dehumidifier with a hair dryer in wet, clammy conditions, you should appreciate this feature.
A LCD screen displays temperature, humidity and the number of hours the unit has run. The AlorAir 85 is lightweight and is easily transported. Unlike some of the other models, this one does not have the ability to couple with ductwork. Exhaust air simply exits via a vent near the rear of the unit.
The reason for this is that it’s marketed as a commercial unit for flood restoration, and connecting to ductwork wouldn’t make sense for a short-term project. Homeowners should still be interested in this exceptional model, simply because of its tremendous capacity.
If you’re buying for commercial use, buy them in pairs for this reason – they’re stackable. You can double the capacity, plus plug them into the same outlet, since they only draw 5.4 amps each (just make sure nothing else in the house or building is running on the same circuit).
Best Feature: Up to 128 Pints Per Day
This is the dehumidifier that took on the Sahara Ocean.
“Wait,” you say. “Don’t you mean the Sahara Desert?”
Yeah. . . . now.
OK, we’re exaggerating, but what isn’t an exaggeration is the fact that this tiny gray box can draw up to 128 pints of water out of the air in a day. Sure, it has to be a dripping wet sauna of a day, but the Dri-Eaz PHD 200 can do it. On a normal day, perhaps it could do 90-100 PPS, but that’s still a lot.
If extreme humidity is a problem in your crawl space, either because of the climate, poor drainage, a shady, soggy backyard or soupy soil conditions, this is definitely worth considering. If your problem is more minor in nature, this model is probably going to be overkill.
They have packed a lot of extras in the PHD 200, whose very model number suggests intelligent operation. For one thing, it’s smart enough to know when it’s time to pump out the condensate. Other models have a gravity feed system, but the PHD 200 has a pump that clears the reservoir automatically, even uphill! (Maximum three feet above the unit.)
When you set the humidistat, the unit will anticipate the need to cycle, even though the humidity is still in the acceptable range. This helps keep the humidity level steady and comfortable.
The PHD 200 can be installed on blocks or hung from floor joists above the crawl space. The suspension kit is an optional, extra purchase but it doesn’t cost too much. It’s small (12.5 x 12.5 x 17.63 inches) but it’s a hefty little brute, weighing in at 63 pounds.
Best Feature: Covers 5200 Sq Ft
This powerful dehumidifier can treat your entire house, even if it’s a big house. Covering up to 5,200 square feet and collecting up to 95 pints of water daily from the air, this unit is a beast. It can draw 95 pints of water out of humid air. Doing the math, that comes to 12 gallons of water per day.
This is not an appliance to be dragged out for emergencies. This dehumidifier is meant to be a day-to-day, everyday partner to your home’s HVAC system. With huge duct ports for both return air and discharge air, it can make a big difference in comfort throughout the house, year-round. Air flow is 265 CFM, which is very strong for a dehumidifier. (By comparison, a two-ton central air conditioning system pulls 700-800 CFM.)
The Aprilaire is built to last. Its aluminum coils are corrosion-resistant and the connections are solidly built and leak free – an important consideration for a system that attracts moisture. Aprilaire products are designed and produced in the U.S.
You can install this unit as a whole-house dehumidifier, where it’s connected to HVAC ductwork; or there’s a basement-only or crawl space-only unit (70 PPD for this version), where the discharge air and return air are limited to the area being dehumidified. A highlight on this dehumidifier is an optional remote control, which can operate the dehumidifier and the air conditioning system when the unit is set to whole-house configuration. It will also pair with your smartphone, and you can make adjustments even when you’re not at home.
For its size and capacity, the Aprilaire 1850 runs fairly quietly. It’s rated at 54 dB which is even less than a refrigerator, for comparison.
It also comes with a five-year warranty, but there are some restrictions. If you want to use this as a whole-house dehumidifier, you must have it professionally installed, or they won’t honor the warranty. If it’s used as a stand-alone unit with no ductwork connections (other than ducting it to the outside), then owner installations are approved.
Best Feature: Compact Size but Big Power (70 PPD Capacity)
This is a minimalistic, no-nonsense crawl space dehumidifier that, despite its size, can treat a basement or crawl space up to 2,600 square feet. It can extract up to 70 pints of water from the air per day, and is suitable for crawl spaces (especially tight ones), basements, garages, workshops and storage areas.
It has what the product literature says is “flow-through” design, meaning that air enters the unit from the front and exits straight out the back, with no turns or twists, unless you want it to. The exhaust port can be rotated to provide horizontal or vertical discharge.
At 12 x 12 x 21 inches, the Santa Fe can fit between floor joists or sit in tight corners of the crawl space or basement, where it can be out of sight, out of mind, but still ever on the job. It gets high ratings from the “green people,” with an Energy Star rating way above efficiency ratings, and its MERV-13 filter provides excellent protection against particulates.
(MERV means Minimum Efficiency Reporting Value. MERV values range from 1 to 16. It’s not an indication of the most a product can do; it’s an indication of the least it can do, so that the consumer can have a baseline to evaluate from. The higher the MERV value, the more efficient the filter will be in trapping airborne particles.)
The Santa Fe has automatic restart, meaning it comes back on in case of a power outage. It’s also engineered to operate at low ambient temperatures. The condensate drain is gravity-fed, but it can be connected to a sump pump or a condensate pump.
Set up is easy. It can be hung from floor joists or placed on blocks. Be sure to set it in a configuration that allows easy access for cleaning and filter cleaning/changing and make sure it’s perfectly level and that the drain hose runs downhill (unless you’re using a condensate pump). You can also purchase a set of risers to rest the unit on.
Best Feature: Massive Capacity
Just when you thought you’d seen the biggest, baddest dehumidifier of them all, along comes another gunslinger with an itchy trigger finger. Dri-Eaz, which has already made our list with the PHD 200, comes along with this water-kicking monster, the F413 Crawlspace Dehumidifier, that can treat areas up to 7000 square feet.
While there aren’t too many houses around 7000 sq. ft., there are stores, restaurants and business offices that are, and this unit can make a big difference, not only in the comfort level for those who inhabit those spaces, but for prevention of mold, mildew and airborne pollutants that thrive in humid conditions.
The LGR can be used as a permanent day-to-day installation in areas where the humidity never takes a break, or as a commercial tool to be taken wherever it’s needed for flood restoration or bad leaks. It’s not a lightweight, but it is portable. You can stack two of these and double the water-extracting capacity, which is rated at a maximum 136 pints per day (or 17 gallons per day) for just one. Keep in mind, that’s the maximum, based on conditions that would rival a waterfall for wetness. For a typical day, you should scale that number back to 80 pints a day.
A real-time display of inlet and outlet temperatures and the relative humidity helps keep track of conditions, and should there be an interruption of electrical service, the unit will restart automatically.
With its built-in condensate pump, it disposes of the water just about anywhere you want it, as long as the destination is not more than three feet higher than the dehumidifier.
Condensate Pumps – How They Work with Crawl Space Dehumidifiers
The design of typical crawl space dehumidifiers puts a lot of emphasis on removing water from the air, but not so much on removing the water from the dehumidifier. Gravity-fed drain systems work well for the dehumidifier, but the water has to be drained to a safe place.
If you can direct the drain hose downhill to a french drain or to a spot where the water won’t wash back against the foundation, then you’re good to go. However, if your desired point of water release is uphill from the dehumidifier, then you need the help of a condensate pump. A condensate pump will draw water through the drain hose and force it through a second drain hose to its final destination, even if it’s uphill from the dehumidifier.
Below are a couple of condensate pumps that you could benefit from.
Best Condensate Pumps for Crawl Space Dehumidifiers
1. Little Giant Condensate Pump (554425)
The Little Giant simple, no-frills condensate pump has a half-gallon tank to store water coming from the dehumidifier. When the water reaches capacity, the pump kicks on automatically to eliminate it. It has an 80 gallon-per-hour discharge rate, so it would take only a minute to void its half-gallon reservoir.
The Little Giant also has a 1/30 horsepower motor. Though it does come in a 1/50 horsepower version as well.
The DiversiTech CP022T comes with a generous 20 feet of 3/8 inch tubing. With that much length, you can put the point of discharge most anywhere you want, even to a point well above the elevation of the pump. It has a lift rate of 22 feet. Even dehumidifiers with built-in condensate pumps can’t go that high!
It can be set on the ground or hung from floor joists by straps. This is a nice little condensate pump with a lot of versatility.
What to Look for in the Best Crawl Space Dehumidifier
Before ordering ANY crawl space dehumidifier, you need to determine the square footage of the crawl space. This is not necessarily the same as the house footprint. Some homes’ crawl spaces are partial, where part of the house rests on a slab and part rests on a foundation. Be sure to measure only the actual crawlspace, and if you can’t physically access the entire crawlspace area, just measure the room or rooms directly above it.
Dehumidifiers and Air Conditioners: Are They Similar?
Humidity control is a function of air conditioning that most homeowners don’t often think about. In the air conditioning process, when superheated refrigerant passes through condenser coils, warm air is drawn in, leaving colder air behind. This air then passes over evaporator coils, where its temperature drops even more. Since cold air cannot hold as much water vapor as warm air, the water vapor condensates, and water exits the unit via a drain.
This is essentially what happens in a dehumidifier. The only difference is, the dehumidifier deals primarily with the water vapor. Therefore, an air conditioner cools a room very well and dries a room less well. By contrast, a dehumidifier dries a room very well, and cools a room less well.So, dehumidifiers and air conditioners are more like cousins than brothers.
Dehumidifiers: Northern vs. Southern States
Homes in the southern states, especially those in the coastal regions are victimized by humidity all year long. Mold spores, mildew and respiratory ailments ramp up along with the humidity. If you live in one of these areas, you already know that.
But how does a crawl space dehumidifier help? Considering that 80 percent of the airflow in a house moves up from the basement or crawl space, then they would help quite a bit. In fact, if you had a in-room dehumidifier and moist air continued to rise from below, then its effectiveness would be compromised.
In northern states, humidity is still a problem, because in some cases, wet soil or foundations never get a chance to dry out, due to cooler climate.
Dehumidifier Ratings Explained: A PHD on PPDs
Dehumidifier ratings of 85, 90, 100, etc. PPDs (pints per day) show the potential of a dehumidifier. The actual production of water depends greatly on how much water is in the air that day. When shopping for a crawl space dehumidifier, it’s much more important to know how much square footage can be treated by the dehumidifier.
The units with a higher PPD rating will not have to run as often, or stay on as long as those with lower ratings. When a dehumidifier is running, it’s like having an extra window air conditioner running, so you want to minimize that to some degree, but spending a lot of extra dollars for the monster dehumidifiers might not be recouped in energy savings.
Ease of Installation for Crawl Space Dehumidifiers
Get something you can DIY. Most of the dehumidifiers on our list are easy to install. Nevertheless, you may want a model that interfaces with your HVAC ductwork, and there are benefits to that, but you’ll have to weigh the extra expense of professional installation against the expected benefits. Here is a list of things you should do to prepare your crawl space for installation of a crawl space dehumidifier.
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