If your home is built on top of a crawl space rather than a basement or other foundations, you’ll know they’re dark, dingy, and when humidity levels rise, damp. 

A damp, humid crawl space is an ideal breeding ground for mold, mildew, bacteria, and wood rot in support beams and floor joists. Mold can affect the air quality of your entire home, having a dangerous impact on your health and that of your family.  

A dehumidifier is a great way to remove the hot and humid air from your crawl space! But not every dehumidifier is designed to operate in these confined spaces. Keep reading to learn about the benefits of under house dehumidification, or skip to my picks of the best you can buy in 2021 using this table of contents.

I’ve worked as a licensed Heating, Ventilation, And Air Conditioning (HVAC) engineer for over a decade. In that time, I’ve worked with some of the best units that are perfectly designed for dehumidifying a crawl space.

I’m going to use that experience to help find your perfect crawl space dehumidifier. I’ve also compiled a helpful buying guide so you can learn and understand exactly what to look for when shopping around.

Crawl Space Dehumidifiers Buying Guide

While a dehumidifier for your crawl space works in the fundamentally same way as a unit for indoor or basement use, there are some important factors to bear in mind when choosing the right one for you and your crawl space.

Moisture Removal Capacity

The amount of moisture a crawl space dehumidifier can remove from the air is measured in pints per day and is also known as the dehumidifier’s capacity. A dehumidifier with a 50-pint capacity can remove 50 pints of moisture from the surrounding air in a 24-hour period. 

Dehumidifier Sizes

Most dehumidifiers generally come with capacities of between 25 and 70 pints, and the size that you’ll need will depend on the size of your crawl space as well as the relative humidity level.

Small Capacity Dehumidifiers (25 To 35 Pints)

The smallest dehumidifiers aren’t designed to operate in a large crawl space. But a small dehumidifier could be ideal in a smaller crawl space of around 1,500 square feet. 

Medium Capacity Dehumidifiers (40 To 50 Pints)

A dehumidifier with a 40- to 50-pint capacity can be considered mid-range. These are best for larger crawl spaces where conditions may be humid and damp but mold and mildew growth hasn’t yet got out of control. 

Large Capacity Dehumidifiers (Over 60 Pints)

A dehumidifier with a capacity of 60-pints or more will have no problem removing excess moisture from a large crawl space of 4,500 square feet. They’re also a good option if you have particularly aggressive mold growth since they can operate in the highest humidity levels of 60% or more.

Ease Of Use

Most dehumidifiers are pretty easy to use, ut there often isn’t a massive amount of room to move around in a crawl space, and it can be tough to see properly too. 

You should choose a dehumidifier that’s specifically designed with these factors in mind:

Humidistat

A dehumidifier humidistat works similarly to an air conditioner thermostat. It allows you to set a specific relative humidity level and will then turn the unit on or off automatically when it detects that moisture levels have gone above or below this figure.

This can save you money off your monthly energy bills by monitoring and reducing power consumption. It can also save you the difficulty of regularly entering your dark and cramped crawl space to check humidity levels and settings. 

Size And Weight

Many of the best crawlspace dehumidifiers are rectangular, which allows them to squeeze into narrower gaps than most indoor home dehumidifiers without compromising on capacity and power.

Crawl space dehumidifiers generally aren’t the most portable machines since they’re often a high capacity and won’t need to be moved around too much once they’re set up. Most weigh between around 50 to 60 pounds, about the same weight as a double mattress! 

Make sure you measure your crawl space before choosing a dehumidifier. Also, check the weight of a unit you’re thinking of buying so you know you’ll be able to move it around by yourself if necessary.

Noise Level

You’re unlikely to hear the hum of a dehumidifier from your crawl space. That being said, air fan motors and compressors can get louder when run for extended periods, and you don’t want to purchase an excessively noisy unit. Most crawl space dehumidifiers will operate somewhere around 55- to 60-decibels, so look for a unit with this in mind. 

Build Quality

The best crawl space dehumidifiers are rugged and robust, perfect for use in the particularly harsh conditions of a crawl space. 

They’ll be able to withstand excessive heat or cold with waterproof technology and hard-wearing components, and they’re made from far tougher materials than the standard plastics used for indoor dehumidifiers, so they won’t rust or break down. That extends their lifespan and means you won’t have to make call-outs for repairs. 

Defrosting System

If you live in an area that can get especially cold during the winter, a crawl space dehumidifier with low-temperature operation is essential. In freezing temperatures, frost can build up inside the unit. The internal coils can freeze and break when this happens, resulting in hefty repair or replacement bills. 

Even if you don’t live in an environment with particularly low temperatures, bear in mind that crawl spaces aren’t always the warmest of areas, and it could take just one night below zero to catastrophically damage your dehumidifier. 

Condensate Pumps

You should look for a crawl space dehumidifier with pump drainage so you’ll have a continuous drainage system. A condensate pump will continuously drain moisture into a drain hole or sink connected to the unit by a drain hose.

Whereas emptying the excess moisture collecting water bucket from an indoor unit a few times a day may be inconvenient, doing the same for your crawl space dehumidifier would be physically exhausting. 

Additional Features

Many modern units come with additional features that could make them the best crawl space dehumidifier for your specific needs. 

Filtration

Many modern dehumidifiers for crawl spaces have an air filter that can filter out dust mites, allergens, and other particles, improving the quality of your crawl space air. Not only does this extend the lifespan of the unit itself, but the now-fresh air can have a noticeable impact on your health and that of anybody else living above.

Remote Control

Regularly entering your crawl space to make adjustments to your dehumidifier can be inconvenient and downright unpleasant. Many of the best dehumidifiers for crawl spaces will come with a remote control that allows you to make those adjustments without having to go into those tight spaces.

Auto-Shutoff And Restart

An automatic shutoff function is another great feature that reduces the number of trips you have to make into your crawl space, which is often cramped and dingy. If the system detects that the water bucket is full or there is another potential issue, the auto-shutoff will kick in and turn the unit off before it overflows or is damaged in any other way.

If you live in an area where a power outage is a common occurrence, especially during the thunderstorms that high humidity brings, you’ll want a unit with an auto-restart function. When you switch the unit back on, it will remember its previous settings, so you don’t have to waste time inputting these again manually.

Best Crawl Space Dehumidifiers Reviews

By now, you probably have a good idea of what you’re looking for, but there are lots of dehumidifiers out there on the market, so where to start? I’ve picked out the best your money can buy today so you can find your perfect crawl space dehumidifier quickly and easily!

Best Overall Product 2021

The Sentinel HDi90 is a powerful dehumidifier that’s a great option for removing excessive moisture from most crawl spaces. It’s similar to the Alorair Sentinel HD90 but comes with a built-in condensate pump. You don’t have to constantly monitor water levels and carry out manual drainage. 

The 90 in the unit’s name signifies that it can remove up to 90-pints of excessive moisture from an entire crawl space per day. That’s enough to cover the square footage of most small to mid-sized crawl spaces as well as those particularly badly affected by mold growth.

The HDi90 is certified by Energy Star, the gold standard for reducing energy consumption as specified by the US Environmental Protection Agency (EPA). Because it consumes less power, you’ll see a noticeable reduction in the cost of your monthly energy bills of around 30% when using this unit. 

The remote control is useful for controlling the dehumidifier from within your home without entering the crawlspace, and an auto-defrost function ensures the unit is built to last through the low temperatures of cold winter months. There’s no auto-shutoff, however, so if there’s a blockage within the drainage system, you may not be aware until it’s too late and has already overflowed. 

It’s also a little louder than some of the other units included in my under house dehumidifier review, which could be an issue for some if it’s underneath a living space or bedroom, but I’d say it’s fairly negligible considering the sheer power of this machine.

It’s still a fantastic dehumidifier that pays for itself in energy bill savings and when you consider the high cost of mold remediation without this unit. Overall, it’s the best dehumidifier for crawl space that I’ve reviewed, and it’s a great commercial dehumidifier for crawl space.

What We Like:

• Energy Star certification
• Heavy duty
• 90-pints of moisture removal per day
• Built-in condensate pump
• Auto-defrost system
• Remote control

What We Don’t Like:

• Comparatively expensive
• Louder than some units at 60 decibels

Best Commercial Grade Dehumidifier For Crawl Space

Another impressive unit from ALORAIR, this commercial-grade dehumidifier, is built to remove 113-pints of moisture per 24-hours. That’s enough for a 1,200 square feet crawl space, well above the average residential crawlspace size. 

A high-density MERV-8 dust filter prevents internal component damage from dust and other airborne particles, prolonging the unit’s lifespan and ensuring consistently efficient operation. It’s washable and easily accessible, though ALORAIR recommends replacement every 2 to 3 months which can cost around $100 each time. 

Another feature designed to extend the unit’s longevity is the rare earth alloy Tube evaporator. This maintains the internal coils heat transfer ability by preventing Freon leakage, which is often a fatal flaw for a crawlspace dehumidifier that leads to hundreds of dollars worth of replacement and repair.

Annoyingly, the remote control is sold separately is priced at around $100, so you’ll have to factor that cost in if you want the benefit of controlling your dehumidifier from the comfort of your living spaces. 

Auto-restart is particularly useful if you live in an area that can regularly expect a power outage, automatically reinstating any previously input settings when the unit is switched back on. Automatic humidistat control allows the unit to measure the humidity in your crawlspace and adjust settings accordingly, saving power and energy bill costs.

What We Like:

• Competitively low price point
• Built-in humidistat
• MERV-8 dust filter
• Auto-restart function
• Tube evaporator
• Auto-diagnosis system

What We Don’t Like:

• No condensate pump
• Remote control sold separately

Best For Large Crawl Spaces

If you’re looking for a powerful dehumidifier that can effectively remove moisture from massive crawl spaces up to 3,800 square feet, then look no further than this unit from trusted brand Aprilaire.

When directly installed into your HVAC system, this unit can drastically improve air quality in your home, acting as an air purification system. It’s designed with convenience in mind thanks to an easy-to-read display and push buttons that enhance usability.

Even with its significant power and airflow of up to 265 CFM, automatic moisture sensors allow the unit to run on-demand to maintain relative humidity levels. This consumes less power, cutting your energy bills down and even affording this unit Energy Star certification. 

A hot gas valve ensures that the unit’s outlet temperature doesn’t get too high. It can further contribute to high humidity levels when this happens, exactly the opposite of what you’d want from the unit!

Longevity won’t be an issue thanks to a dust and particle filter to protect the internal components, so you’re getting a long-lasting return on your initial investment. If you’ve struggled to reduce humidity in a large crawlspace, this unit could be your perfect solution.

What We Like:

• Removes 95-pints of moist air per day
• Effective in very large crawlspaces up to 3,800 square feet
• Relative humidity display
• Digital control panel on the front or top of the unit
• Dust and particle filter
• Energy Star rating

What We Don’t Like:

• Heavy unit
• Warranty requires professional crawl space dehumidifier installation

Best Small Crawl Space Dehumidifier

If your crawlspace is on the smaller side, why waste money splashing out on a unit that is not only too big for this confined space but will consume more power than you need and add unnecessary dollars onto your energy bills?

This unit comfortably removes saturation from the air of 1,300 square foot crawl spaces at a rate of 120-pints per day. Its Energy Star rating means it’s efficient while doing so, reducing your power consumption and energy bills by around 30% each month.

Auto-defrost enables the unit to operate in low temperatures of down to 36℉, so it’s a solid choice if you live in a climate with particularly biting cold weather. There’s no built-in drain pump, however, so you’ll need to attach a pipe and place the unit above a drain, for instance, put on concrete blocks to ensure continuous drainage.

This is a good crawl space dehumidifier that you should seriously consider if you’re looking to dry air in a narrow or compact crawl space. It’s affordable and does all the things it’s expected to without you having to pay for more.

What We Like:

• Energy Star certification
• Small and compact design
• Remote control
• Auto-defrost

What We Don’t Like:

• No built-in condensate pump

Crawl Space Dehumidifiers: Frequently Asked Questions

Can I Use A Regular Dehumidifier In A Crawl Space?

You cannot use a regular dehumidifier in a crawl space since its capacity will not be enough to effectively dehumidify a crawl space. A high-performance unit that is also robust enough to withstand the harsh conditions of a crawl space is essential.

Will Any Dehumidifier Work In A Crawl Space?

The best dehumidifier for crawl spaces has a powerful dehumidifying capacity, optimal square feet coverage, high energy efficiency, and a continuous drainage system. 

Many indoor home units will not meet these criteria, so you should look for a dehumidifier specifically designed to be used in humid crawl spaces.

Where Should A Dehumidifier Be Placed In A Crawl Space?

You should place your crawl space dehumidifier where it can be easily drained and where the airflow out of the system is not blocked and hampering air circulation. This will ensure optimum dehumidification for longer periods. 

How Long Will My Crawl Space Dehumidifier Last?

With proper use and crawl space dehumidifier maintenance, your unit should last between 3 to 5 years. 

My Final Thoughts

Nowadays, plenty of dehumidifiers are available that are suitable for use in the dark, cramped, and humid conditions of your crawlspace. Some have more extra features than others, but they’re all effective and efficient when it comes to turning humid air into dry air. 

The ALORAIR 120PPD should be your go-to unit if your crawl space is under 1,300 square feet, whereas at the opposite end of the scale, the Aprilaire 1830 Pro can perform in massive crawlspaces up to 3,800 square feet. 

The ALORAIR 113-pint dehumidifier offers great value for money, but the best overall unit I’ve reviewed has to be the ALORAIR Sentinel HDi90.It provides a great combination of efficacy, efficiency, and useful extra features that make humidity control simple and convenient.

Don’t forget to refer back to this buying guide whenever you need, and you can look forward to the improved air quality a crawlspace dehumidifier brings!