In a Nutshell:

The Quest Dual 105 Overhead Dehumidifier is superb quality, high capacity dehumidifiers intended for the largest growing operations. Recommended for any serious grower with a large indoor growing space.

Feature Set
Ease of Use
Value for the Money
Brand Reliability*

Overall Rating

* Brand Reliability is a measure of the strength and longevity of the brand, which by extension, is a measure of the level of support you can expect.


  • High water extraction capacity
  • Energy-efficient
  • Excellent MERV-11 filtration system


  • High initial cost
  • May be expensive for some buyers
Quest Dual 105 Overhead Dehumidifier

Recommended For: Any serious grower with a large indoor growing space.

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Do you grow plants of any kind indoors? Are you looking for a world-class, robust dehumidifier to keep the humidity level of your growing space precisely controlled? If so, and if you’ve got the money to spend, then a Quest dehumidifier is what you want, and in this review, we’ll tell you exactly why that is and what these remarkable machines can do for you.

Quest is an industry leader, and by the time you reach the end of this review, we think you’ll agree; even if you opt for a less expensive solution, these dehumidifiers are flat out amazing.

In this review, we’ll be focusing on the Quest Dual 105 Overhead dehumidifier, but understand that it is part of a family of functionally similar dehumidifiers with capacities ranging from 105 to 205 pints of moisture extraction per day. If the one we talk about here isn’t big enough for you, you can get a more powerful version of this unit that’s big enough to meet your needs no matter how big your growing operation.

Let’s take a closer look, starting now!

An Overview of the Quest Dual 105 Dehumidifier

These units are workhorses, through and through. They’re pure function over form. They’re not pretty, and they don’t have to be. They do two things: They pull lots of water from the air, and they filter the air that enters the system and filters it well. That’s it. That’s what you’re paying top dollar for when you buy one of these, and that’s exactly what you get.

Before we get into the particulars, let’s take a quick look at the core stats of the smallest unit (Quest Dual 105 Overhead dehumidifier) in this family of products:

Leftview, Quest Dual 105 Overhead Dehumidifier, White Color
  • Overall Product Dimensions: 20.25” x 21.75” x 38”.
  • Product Weight: 140 pounds.
  • Extraction Capacity: 105 pints per day.
  • Reservoir Size: None.
  • Power Cord Length: 10 feet.
  • Included Drain Hose Length: 8’ (3/4” Threaded NPT).
  • Power Supply: 530 Watts (max).

A few things to note here. First, these units were meant to be rack or shelf mounted, probably up near where your grow lights are. The power cord is long enough to allow for that, and if needs be, you could deploy a heavy-duty extension cord to give yourself even more flexibility.

There’s no reservoir here. These units rely on a gravity drain system, which works well given that they’re meant to be mounted high, and Quest includes an 8’ drain hose with the unit. That may or may not be long enough for you, depending on where you’re planning to direct the water and where the unit is located in your space. If it’s not long enough, though, you can easily buy your own longer hose and arrange to taste.

The impressive thing, though, is the power draw. 530 watts is almost absurdly low given what these units are capable of, and this is one of the major reasons for considering a Quest over just about any other model. You’re not going to get that kind of efficiency anywhere else, and that’s going to save you big bucks on your monthly power bill. We’ve reviewed smaller units that only extracted about half as much water per day and used as much, if not more, power. Quest is beyond impressive, where efficiency is concerned.

Quest Dual 105 Overhead Dehumidifier Features

We’ve already mentioned the two most compelling features of the Quest Dual 105 dehumidifier: Its efficiency and its raw water-extracting capabilities. There’s really not a lot to these units. Where smaller units sport an LED-based control system that allows you to dial in a specific humidity level target, Quest units use a simple dial with several broad humidity targets: Humid, Normal, and Drier. These correspond to the following ranges:

  • Humid = 80% to 90% relative humidity.
  • Normal = 50% relative humidity.
  • Drier = 20% to 30% relative humidity.

Tweaking the dial within these bands will allow you to control the humidity the machine is shooting for more precisely, but the idea here is clearly to rely on your hygrometer to tell you when you’ve reached your ideal humidity level and make adjustments to your Quest unit as needed.

Side View, Quest Dual 105 Overhead Dehumidifier, White Color


Note that Quest also sells a wall-mounted humidistat that will give you an accurate read of the humidity in a part of your growing space different from where the machines are located and allows you to tie one (or several) units to it so you can control the humidity from there, and more precisely than you can from the controls on the units themselves. Depending on the size of your growing space and how many units you’re deploying, this add-on is provisionally recommended.

Back View, Quest Dual 105 Overhead Dehumidifier, White Color

MERV-11 Filters

Also, note that all of the dehumidifiers in this family of products are outfitted with MERV-11 filters, which do a much better job at purifying the area in your growing space than the simple mesh filters that come with lesser machines.

While the filters in much less expensive machines need to be cleaned every two weeks, you can run your Quest for up to six months before you’ll need to pause long enough to give the filter a good cleaning. Not only do their filters trap more pollutants, but you don’t have as much periodic maintenance – that’s a win for you on two different fronts!

A final thing worth mentioning here in our Quest 105 dehumidifier review is this:  Given the incredibly high production values of Quest units, you won’t have any issues when it comes to recycling and reclaiming the water they pull from the air to reuse on your plants later.

When you’re dealing with machines made from relatively low-quality components, there’s always the possibility that copper or aluminum will leach into the extracted water, making it unusable.

The bigger your growing operation is and the more water you’re feeding into the system, the more important reclaiming that water is.  Quest units make that a relatively simple proposition.

Pros and Cons of Quest Dual 105 Overhead Dehumidifier

The Quest 105 Dual dehumidifier pulls a lot of water out of the air, and its big brothers pull even more. It sips power, and it’s got an excellent MERV-11 filtration system. Those are the reasons you’ll want to buy one (or several).

The only real downside to any unit in this product family is the price, and even that’s not a deal-breaker because, in the long run, the money you save on your monthly electric bill will pay for the unit. Unfortunately, you’ve still got to have a big pile of cash to buy one initially, and that might be beyond the capabilities of some. Other than that, these dehumidifiers are absolutely rock-solid.

Quest Dual 105 Overhead Dehumidifier Review Conclusion

Quest is an awesome company.  They make unbelievably good high capacity dehumidifiers that are the most efficient we’ve ever seen, and they offer world-class customer service and support.

Even if you can’t afford the Quest Dual 105 Overhead dehumidifier initially, if you have a large indoor growing operation, we’d recommend saving your money for a few months until you can afford one rather than getting a far less efficient, less expensive unit. You’ll save money in the end and are almost certain to get a far better and more robust product. We can’t recommend these highly enough.

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