How Does a Dehumidifier Work? How Does it Work and Why You Need One

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Regardless of the season, a damp basement or crawl space can really degrade the livability of your home. Luckily, there’s an appliance that has been designed to effectively and efficiently resolve this problem – the dehumidifier. Dehumidifiers are a purpose-built home appliance that are able to eliminate ambient moisture within a space, thus preventing undesirable contaminants such as dust mites, mold, and more from thriving.

“But, how does a dehumidifier work?” I hear you ask. As it turns out, the way dehumidifiers work is actually quite interesting. For example, you may not have known that there are two distinct types of consumer-grade dehumidifier.

Moreover, you may not have known that consumer-grade dehumidifiers are quite different to their commercial grade counterparts (based upon their dehumidifying capacity, primarily).

The very simple description of how a dehumidifier works is just below – keep reading for an in depth guide.

how does a dehumidifier work

How Does A Dehumidifier Work?

Standard dehumidifiers operate by drawing in moist air and passing it through a series of cooling coils, which are filled with a refrigerant.

From there, moisture condenses out and collects in a removable basin while a fan blows the newly dried air out of the unit.

The Two Main Types Of Dehumidifiers

refrigerant dehumidifier

Before going too much further, though, let’s establish one fact about dehumidifiers – they do not all operate precisely alike. In fact, consumer dehumidifiers can be separated into two distinct categories based upon their specialized method of prizing ambient moisture out of the air.

Both dehumidifier types hold the potential to improve your home’s environment as well as eliminate a significant risk for unsanitary organism growth indoors. So, you should absolutely read on and learn how each dehumidifier type operates, as well as the benefits (and potential drawbacks) of using each dehumidifier type.

Refrigeration Dehumidifier

First up are the refrigeration dehumidifiers.
These models are considered the standard in this appliance class due to their simple, yet effective, method of condensing ambient moisture out of the air. 

Desiccant Dehumidifier

In juxtaposition, desiccant dehumidifiers (sometimes known as “absorption dehumidifiers”) use an entirely different dehumidification method that equates to “squeezing” or “mopping” moisture out of the air.

Learn more: Whole house dehumidifiers – how they work and what they cost.

How A Refrigeration Dehumidifier Works

how a refrigerant dehumidifier works

Chances are, you’ve seen a refrigeration dehumidifier in action before or, at the very least, you’ve heard one in use. Their continuous hum is associated with all dehumidifiers in general and derives from their primary method of extracting water vapor out of the air.

This process starts when a refrigeration dehumidifier is plugged in. 

  1. A series of sensors are activated that “sniff” out whether or not an undesirable amount of water vapor is hanging in the air around the unit.
  2. If these sensors cross a certain threshold (which is usually determined by the user), they will kick the full unit into action and begin the dehumidification process.
  3. Using a reversed fan, a refrigeration dehumidifier draws in warm, moist air through the grill on unit’s outward facing side.
  4. From there, the warm air is channeled past freezing cold pipes that are filled with a specialized type of chemical coolant (similar to the type found in air conditioners).
  5. As the air cools in the presence of these chilly pipes, the water vapor in the air condenses out and begins to collect in a specialized basin (often at the unit’s base).
  6. As this collection process occurs, the newly-cooled air continues through the unit and passes a heating element.
  7. This warms the air back up to room temperature before it is blown back out through another set of fans (typically on the unit’s sides or rear).
  8. Meanwhile, a float switch in the collection basin will rise and rise until, after reaching the tank’s full capacity, it automatically turns the entire unit off.

Learn More

woman fixing a leaking dehumidifier

Why Is My Dehumidifier Leaking Water?

there are numerous causes of dehumidifiers leaking water – they are usually quite easy to fix.

dehumidifier leaking refrigerant freon

Is Your Dehumidifier Leaking Freon?

Refrigerant dehumidifiers use a special gas to operate correctly?

If your unit is leaking freon then it needs to be fixed.

featured image for how to use a dehumidifier effectively article

How To Use a Dehumidifier Effectively

Make sure you have your dehumidifier set up correctly so it operates at peak efficiency.

Pros and Cons of Refrigerant Dehumidifier


  • More economical when dealing with warmer, wetter air
  • Units tend to be more affordable
  • Easy to manage due fully automated process


For more insights into the basic operation of a refrigerant dehumidifier, check out this video:

How A Desiccant (Absorption) Dehumidifier Works

how a desiccant dehumidifier works

If you’ve run into a desiccant or absorption dehumidifier in your years of homeownership, you may not have known it immediately. That’s because, for the most part, consumer-grade desiccant dehumidifiers look like refrigeration dehumidifiers.

But they often lack the slotted grill seen on most refrigeration dehumidifiers, which should be your first clue that something unique is going on inside.

  1. Most modern desiccant dehumidifiers make use of a series of sensors that enable them to automatically detect when ambient moisture in the surrounding area is unsuitably high.
  2. When this occurs, desiccant dehumidifiers typically turn on quietly and initiate the process of “mopping” the air without much added fanfare.
  3. The unit draws in warm, moist air through an outward-facing duct
  4. From there, the warm air is immediately channeled into the unit’s primary dehumidification system, which is made up primarily of a large wheel covered in an absorbent gel known as a desiccant.
  5. This wheel continuously spins, allowing it to collect up moisture from the air as it passes through. Some models even heat this wheel, allowing for a more efficient collection process.
  6. Most modern desiccant dehumidifiers pass air through this wheel-based “squeezing” process a couple times before channeling it passed a heater, which dries out the air before returning it to the environment.

In all, this process is a bit slower, but most users find desiccant dehumidifiers more desirable due to their ability to precisely manage in-home humidity with a thermostat.

Learn more: How to use a dehumidifier

Pros and Cons of Desiccant Dehumidifiers


  • Quieter operation
  • More precise control over humidity through use of a thermostat
  • More efficient when working at lower temperatures


  • Tend to be slightly more expensive

For more information on desiccant dehumidifiers, check out this informative video:

The Mop Up

As a quick review, refrigeration dehumidifiers operate by drawing in moist air, chilling it until the moisture condenses out, and then rewarms it. Desiccant dehumidifiers, on the other hand, extract water vapor by passing moist air past a rotating wheel of absorbent material.

That’s essentially it!

Dehumidifier operations are fairly simple, regardless of whether you are utilizing a refrigeration or desiccant unit. Now that you know how your dehumidifier works, you can better utilize its core operations to improve the environment within your home.

If you’re in the market for a new dehumidifier, though, then you should definitely give the H0melabs 4500 a look.

Also check out our guide on The Best Dehumidifier for Basements.

If you have any more questions about your dehumidifier, feel free to comment! We’re here to help you better understand your home appliances and the numerous ways in which they can improve your home’s day-to-day maintenance.

Do you have any questions relating to this article? Email us at [email protected] or call us on +1 (310) 961-4908

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Aaron is the founder of and Essential Home and Garden. With over 15 years of hands-on experience in home ownership, lawn care, and gardening, Aaron is a seasoned expert in areas like lawn care, DIY, HVAC, and pest control.

2 thoughts on “How Does a Dehumidifier Work? How Does it Work and Why You Need One”

  1. Avatar photo

    I am wondering why my dehumidifier is leaking directly onto the floor. It isn’t collecting in the bucket. I did just clean my filter which was marginally dusty so I don’t think that’s the problem.
    Thank you.

    • Aaron Green

      Hi Karen, check the the unit is sitting on a flat surface. I would also check that you haven’t accidentally dislodged a hose or something else while cleaning the filter.

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