If you’re looking for a tried and tested crawl space dehumidifier then look no further than the AlorAir Sentinel HDI90. Luckily there are other great options such as the Aprilaire 1830 Pro, which we also review and compare to the HDI90 in this buying guide for the best Crawl Space Dehumidifiers.
Dehumidifiers are a commonly overlooked appliance in today’s average household, and most people simply don’t realize the importance of such units. In fact, most of North America sees an average humidity above 60%, and exceeds that during the summer months. Such conditions are breeding grounds for mold, mildew, and dust mites, which are hazardous to both people and homes.
Whether the intended use is water damage restoration, focused dehumidification, or just general household applications, picking the right dehumidifier is essential to getting the most out of your purchase.
Today’s market has an extensive variety of options utilizing everything from peltier technology, to silica gel desiccant designs. Admittedly, much of this is marketing material, but it still complicates the process of choosing the right unit. To add to the confusion, ridiculous acronyms like AHAM and PPD are thrown into the mix. Honestly, such terms are alien to anyone outside the dehumidifier industry, so if that’s you, keep on reading.
VIDEO | A Closer Look at the AlorAir Sentinel HDI90
Before going on, let’s establish a basic understanding of the primary ratings used in this industry. Most companies selling dehumidifiers today comply with each other and use the standard rating of PPD. This simply stands for Pints Per Day, and refers to the amount of water a particular unit is capable of removing from the air in a day. A pint is equal to 16 ounces, or about 473 millilitres. So a unit rated at 30 PPD should remove around 30 pints of water from the air within a 24 hour period. Pretty simple, right? Except, on its own, this rating doesn’t fully define the capability of one unit from the other. For example, if two identical units both rated for 75 pints per day are set up in varying environments, let’s say a desert and a jungle, the one in the jungle is likely to pull significantly more than 75 pints of water in a day, and the opposite is true for the one in the desert. This is because the air in a jungle naturally has a higher water content, and the dehumidifier will have to cycle much less air to achieve 75 PPD. So if left unspecified, companies have the freedom to declare any PPD rating they want, simply by varying the climate in which they test their product.
This is where the term AHAM comes in. Since temperature and relative humidity both affect how easily a dehumidifier can remove water from the air, these conditions must be constant from manufacturer to manufacturer. Today, there are three different ‘presets’ that manufacturers use to determine the PPD of a unit. The most common of these is referred to as AHAM conditions (the Association of Home Appliance Manufacturers) and is quite simply defined as 80° Farrenheit, and 60% humidity. Another common climate is called Saturation, or 90° Farrenheit at 90% humidity. Often, PPD ratings for both conditions are given, although AHAM is commonly regarded as the standard because it best describes the indoor conditions in most American homes.
Fortunately, choosing the right dehumidifier doesn’t have to be that complicated. All marketing fluff aside, most available units can be put into three different categories based on their size, capability, and intended use. The first of these categories is best referred to as the desktop category. These units (as the name implies) tend to be small, low power consuming, and are designed for single rooms and small spaces. They are often advertised for use in offices, with sleek low profile designs that either plug into the wall, or are battery operated. This allows them to be kept in small discrete corners, or used in crowded rooms short on space. While it sounds fantastic, most desktop dehumidifiers don’t even advertise the industry standard rating of PPD. And the ones that do, usually claim less than a pint per day. In other words, most of these little units are barely more than expensive white noise machines for your desk, and are only worth it if intended for use in a single room.
Consider : ALORAIR LGR : With State of the Art LGR Technology
The second and most common category is sometimes called the typical home unit. Brands like Frigidaire and LG are big names in this market, selling large, upright, standalone boxes. Most people end up going this route because these products are well-marketed, portable, and well-priced. All things considered, these units offer a good balance between capacity, efficiency and portability. However, their upright design and bulky profile often makes them impractical for use in crawl spaces, or areas requiring focused dehumidification.
This is where the third and final category enters the conversation. These dehumidifiers place as much emphasis on practicality as possible, which results in very small, powerful units. Most mainstream brands like LG and Frigidaire don’t compete in this category, because more specialized companies like Alorair and Aprilaire dominate the market. For applications like focused dehumidifying (drying a smaller, concentrated area) or water damage restoration, units with high PPD ratings (>50 PPD) are a necessity, and this is exactly what you get with these brands. As well, such units are ideal for crawl spaces and attics, and are usually designed in a horizontal orientation. This primarily serves to allow use within small crawl spaces, but also makes transporting and carrying the dehumidifier significantly easier. Overall, units in this category are designed to be versatile, effective, and well-suited for tight spaces.
VIDEO | Dehumidifier Buying Guide : Why You Should Buy One
After determining the type of dehumidifier that suits your needs, the next step is choosing the appropriate size. If you’ve made it this far, chances are you already have some idea in this regard. However, there are few things to take into account to be sure you end up with the right product. Firstly, consider the size of the room. Next, consider the condition the unit will be exposed to as this can play a significant role in the unit you choose. In most household products, room volume is approximated by giving a rating based on the square footage of the space. For example, Alorair states that their mid-sized, 90 PPD unit is suitable for spaces of up to 2600 square feet. Lastly, recognize that appliances like washing machines, dryers and especially showers can strongly affect the relative humidity of an area. If the area requiring dehumidification has these things, it may be necessary to opt for a unit rated with a higher PPD.
As a general rule of thumb, 1 PPD for every 25-40 square feet should be sufficient for most homes, although, like I previously mentioned, you may want to opt for a more powerful unit depending on what is within your area and whether or not your basement or crawl space differs from AHAM conditions. This is merely a suggestion derived from ratings imposed by two different manufacturers of similar units (AlorAir and HoneyWell) and is most relevant to units with ratings higher than 70 PPD.
Buyers Guide and Overview : AlorAir Sentinel HDI90 & Aprilaire 1830 Pro
In many cases, the area needing dehumidification can be cramped and hard to get to. For this reason more specialized products are available and marketed specifically as crawl space dehumidifiers. While these products technically fit into the aforementioned third category, not just any dehumidifier can be used in these cases. These units must fit a very specific criteria, and be reliable enough to be left running for extended periods of time.
To name a few, crawl space dehumidifiers must :
- Be compact enough to maneuver in inconvenient spaces
- Be light enough to carry
- Have some method of draining the collection container remotely
- Not require constant attention to keep running
With that said, let’s get right into looking at two of the top dehumidifiers available today. This will be a fairly in-depth look at these comparatively priced units suitable for use in crawl spaces and basements. And best of all, both products are sold for under a thousand dollars.
AlorAir vs Aprilaire
Both AlorAir and Aprilaire are reputable names in the air care world, and each manufacturer offers a whole host of related items. In North America, Aprilaire is probably more well known, because their products are designed and manufactured in the United States. Alorair products are made in China before being shipped all over to where they are sold. This means North American Aprilaire customers receive more culturally familiar customer service, while much of AlorAir’s website appears to be straight out of Google Translate’s rear end. Still, in researching their products, I found quick and easy access to customer support via the live chat function on their website, whereas Aprilaire only supports email. In the end, both companies provided immediate support and sufficiently answered my questions. It is also worth noting that AlorAir has a sister company under the name of BaseAire which sells rebranded equivalents to many of Alorair’s products.
Review : ALORAIR Sentinel HDI90
Best Crawl Space dehumidifier for the money
Ideal for : removing Damp, Mould, Rot and Moisture from Museums/Sports Halls, Water Damage Restoration, Vehicle Storage, Basements/ Cellars, Storage Areas, Garage, and Basement. Keep Dry and Restrain Bacterial Growth.
- Energy Star Certified Dehumidifier. Quickly and effectively removes moisture with less energy than conventional dehumidifiers without racking up your energy bill, saving you money.
- Remove 90 pints per day at AHAM condition, 198 Pint at saturation
- up to 2,600 sq. ft, fit for any basement, crawl space, storage areas, garage, any large room, or commercial use.
- Heavy Duty Condensate Pump: When removing large amounts of moisture, the condensate pump keeps the dehumidifier running smoothly and efficiently by pushing collected water out of the area continuously.
- Optional Remote Control – This professional dehumidifier is designed with the remote monitoring function, which makes this unit an ideal choice for places where remote sensing and controlling is required, It is also a good choice for sound insulation and saving space usage.
- Automatic Defrost – a quick and efficient defrosting process, truly makes the dehumidifier able to work at a low temperature (36 degrees Fahrenheit), if frost is detected on the coils, an automatic defrost cycle runs to avoid frost build-up and issues associated with that build up. Makes the unit work continuously and efficiently without periodic stopping during the defrosting process, not only saving the energy but also making the unit last longer.
- You can save up to $250 per year in energy costs. Once you are able to maintain a consistent RH 50 %, no need to keep the thermostat at low, uncomfortable temperatures once used in an effort to control humidity.
OVERVIEW / ALORAIR Sentinel HDI90
Alorair’s main lineup of dehumidifiers all share the name ‘Sentinel’, followed by a short PN ending in two numbers. These numbers (e.g. 90, in HDI90) refer to the capacity of the unit in PPD. The ‘I’ in HDI90 indicates that the unit has a built-in condensate pump to help drain the water, so AlorAir’s similarly priced Sentinel HD90 is essentially the same unit without this feature. This method for interpreting part numbers is consistent across all Sentinel units. It’s not clear what the big ‘HD’ means, but for what it’s worth the term ‘Sentinel’ refers to a soldier standing guard over something.
AlorAir’s Sentinel HDI90 is the first unit we’ll be looking at today. This is a 90 PPD horizontally oriented dehumidifier that is marketed mainly for use in basements and crawl spaces. It has most of the flagship features advertised by other manufacturers, with one or two exceptions that we’ll touch on later. That said, there are some major selling points that make this unit worth considering.
The first of these selling points has to do with a common limitation that plagues most dehumidifiers, and that is temperature. To understand why temperature affects a dehumidifier’s ability to dehumidify, we’ve got to understand the basic principle that allows refrigerant dehumidifiers to function.
If you’ve ever sat outside on summer day with a cool can of beer or a glass of lemonade, you’ve probably taken note of the condensation that forms on the side. This happens because warm air can hold significantly more water vapour than cool air. So when the warmer surrounding air gets cooled by the sides of the can, the excess water is effectively ‘squeezed’ from the air and onto the sides of the can. Essentially, dehumidifiers work on this same principle, although the can of beer is swapped out for an evaporator coil.
At the end of the day, there is a pretty firm limit on how much these units can dry the air. The biggest limitation usually has to do with how big of a temperature difference they can create between the evaporator and the air, without getting too cold. If the coil dips below freezing, the water can’t drip into the collection bucket and ends up clogging the fins. To get around this, most units have a defrosting cycle built in to melt away the build-up of ice, which entails shutting off the refrigeration compressor and blowing ambient air over the coil. The HDI90 uses this same system, however, it’s also got a nifty little indicator light to keep you updated on this process.
While this limitation applies to all refrigerant dehumidifiers, AlorAir claims their units can function well below the temperature of most other units (down to 33° Fahrenheit, or half a degree centigrade). While I recommend taking this claim with a grain of salt, it’s reassuring to know the unit was developed with low temperature operation in mind. So, if your crawlspace or attic isn’t insulated, the HDI90 could have an advantage over the Aprilaire 1830.
Another thing that may sway people towards this unit has to do with maintenance. As with any appliance, the components aren’t going to last forever, so having the option to switch things out and replace parts when they fail can be extremely valuable. AlorAir provides incredible support in this area by offering a wide variety of replacement components via their website. But they don’t stop there, as the company has an entire YouTube channel for posting promotional videos and DIY maintenance walk-throughs. So, this is definitely a major plus to anyone willing to extend the life of their purchase with a little determination (though keep in mind the manual still advises against it).
|ALORAIR Sentinel HDI90||Specs :|
|Air Flow: 210 CFM, 350 CMH||Feet: Adjustable feet|
|Supper COP: 2.69 L/kWh||Draining: Condensate Pump|
|Sound Pressure Level: <58 dB(A)||Size for: Up to 2,600 Sq.Ft.|
|Capacity: 198 PPD at Saturation, 90 [email protected]||Humidity Range: 35~90%|
|Temperature Range: 33.8~104 ℉|
Intended Use :
While the Sentinel HDI90 and the Aprilaire 1830 both advertise an intended use within crawlspaces and basements, there are a few small differences that suggest they were designed for slightly different applications. For example, Aprilaire’s 1830 comes with adapters to attach ductwork, and doesn’t have handles. This implies the unit is meant to be used in permanent setups, whereas the AlorAir HDI90 offers ductwork collars as an option and comes with handles. That said, the HDI90 is significantly heavier, at about 86 lbs, compared to Aprilaire’s 1830 at around 67 lbs. Each of these units has its upsides with regards to maneuverability, however both are probably better suited for permanent setups.
So far I have been consistently positive in addressing the HDI90, although it’s not without faults. One feature in particular that is missing from this unit is an automatic shut off to prevent internal overflow. Normally, units with collection basins (unlike these two) have a float switch built in to signal when the unit reaches max capacity. In the case of these two products, there simply isn’t a container for liquid to build up in, so it’s incredibly important to ensure that the unit always has a way to rid itself of the water. Both units come with a hose to direct the water towards a drain, but in the case of blockage, there isn’t anything to stop AlorAir’s unit from overflowing internally. Aprilaire has apparently thought this through, because the 1830 comes with a built-in float switch.
Another fault to the HDI90 is, as mentioned before, its weight. At 86 lbs, it isn’t the lightest unit on the market (although it’s also not the heaviest). There are a few reasons as to why the HDI90 tips the scales so much, but it likely comes down to the higher capacity (20 PPD higher than the Aprilaire’s 1830) and the extra weight of the condensate pump (which isn’t present on Aprilaire’s unit).
Review : Aprilaire 1830/ 70 Pint
Best CrawlSpace Pro Dehumidifier Overview
Designed for spaces up to 3800 sq.ft.
- BUILT TO LAST with corrosion-resistant aluminum coils, Aprilaire Dehumidifiers are designed and manufactured in the U.S.A. by Aprilaire, the leader in indoor air quality solutions
- REDUCES & CONTROLS BASEMENT HUMIDITY to help prevent damp carpeting and furnishings, mold, mildew, and odors
- HELPS PREVENT MOLD, TERMITES, STRUCTURAL WOOD ROT, AND ODORS in a sealed crawl space
- REMOVES UP TO 9 GALLONS (70 pints) of water per day
- NO MESSY WATER TRAY TO EMPTY and simple to set up – just place a hose or place dehumidifier over a drain, level it, plug it in, set the target humidity, and you’re done
- SET IT AND FORGET IT control automatically starts dehumidification when humidity above target is sensed
The Aprilaire 1830 70 Pint Crawl Space Pro Dehumidifier (we’ll call that the 1830 Pro from now on) really offers something completely different from the HDI90. While it’s slightly less powerful and doesn’t boast the same specs, a huge selling point is the superior build quality. The American engineering behind this product means it’s built to be reliable and functional. In a nut-shell, you know what you’re getting. There’s not much marketing fluff to wade through, nor does Aprilaire sell a low quality product. So if you’re in search of an extremely compact and trustworthy dehumidifier, this is quite possibly the best option.
As mentioned before, the biggest thing that sets the 1830 Pro apart from its competition is its compact size. At just 14.5” by 12.5” by 25” deep, this horizontally oriented dehumidifier is one of the smallest in its class. Having such a tiny profile means it can be set up just about anywhere, which is really handy for a unit meant for crawl-spaces. Aprilaire’s website advertises that the unit can handle a space up to 3800 square feet, which means this unit could even work as a whole house dehumidifier in some cases.
Another really unique feature built into this unit is called time ventilation mode. This essentially means the unit can double as a simple ventilation system by keeping the blower on even when it’s not running the refrigeration system. Not only does this improve air quality, but it helps to reduce short cycling, which can be a common issue in many crawlspaces. While a feature like this may not be a deal-breaker, it certainly shows the thought that went into developing this product.
Choosing a product from such a developed company like Aprilaire also comes with another more unique set of benefits. They offer everything from home filtration systems to thermostats and even humidifiers as a way to improve your indoor air quality. Because they offer such a wide variety of healthy air products, they needed a way to tie everything together. While their thermostat products can be set up to control humidifiers, dehumidifiers, furnaces and air conditioners, there’s no way to remotely control the climate in your home this way. This is where Aprilaire’s app comes in. The app is available for free on both apple and android devices and offers immediate control of the climate in your home or cottage. Having a feature like this offered for free is especially handy if you don’t fancy crawling through your storage everytime the humidity needs adjustment.
A Quick Summary
Both of these Products have their advantages and disadvantages, although neither is a poor product. Both seem to receive positive reviews on popular sites like Amazon, and each unit is backed by a 5 year warranty. So if someone’s reading this trying to decide between the two, I’d say it really comes down to where you plan to use it. For basement settings or areas without a drain you’re most likely better off with the AlorAir HDI90. Its condensate pump and handles mean it is better suited for a wider variety of settings, whether that be a room with water damage or an attic. The Aprilaire 1830 on the other hand seems to be designed exclusively for permanent settings or HVAC systems. Its high power blower and out-of-the box duct-work flanges makes it ideal for these cases, and the extra little features like the remote humidistat app and time ventilation mode really give it an edge in tight crawl-spaces. Both are energy star certified so the costs after purchase will be comparable, although you also need to factor in installation costs and any additional features like ductwork or extension cords.
In the end neither is a waste of money. Buying any dehumidifier is going to increase the air quality in your home. I hope this information helps not only to clear up any confusion around these appliances, but also helps you make an educated decision towards a more comfortable living space.
VIDEO | What Size Dehumidifier Do I Need?
Reference / Bibiliography :
- “Dust Mites.” American Lung Association
- Rothman, Rachel, and Lynn Redmile. “Everything You Need to Know About Dehumidifiers for a Healthy Home.” Good Housekeeping, 14 Apr. 2021,
- VIDEO : “Alorair Sentinel HDi90 : Basement Dehumidifier 90 Pint with Pump Crawl Space Humidity Controller.” YouTube, YouTube, 13 Mar. 2017,
- Consumer Reports, director. Dehumidifier Buying Guide (Interactive Video) | Consumer Reports. YouTube, YouTube, 4 June 2015,
- Sylvane Inc, director. What Size Dehumidifier Do I Need? | Sylvane. YouTube, YouTube, 1 Aug. 2014,
- Fields, Zach, director. What’s Inside a Dehumidifier? YouTube, YouTube, 27 Aug. 2020, www.youtube.com/watch?v=y4vJTRmhhAM.
- “AHAM vs Saturation Explained: AerIndustries Blog.” Aer Industries, 21 Jan. 2019,
- “Dehumidifier Buying Guide.” Consumer Reports,
- Crawl Space Ninja. Aprilaire 1820 Dehumidifier Overview | 70 Pint Per Day Dehumidifier for Crawl Spaces and Basements. YouTube, YouTube, 12 July 2018,
- Maintain Indoor Relative Humidity. HGTV. (n.d.).