What Is The Difference Between A Humidifier And A Dehumidifier?

by Véronique Raymond
humidifier review

Humidifiers and dehumidifiers are two of the most common household products, but many people don’t know the difference between them or why they are actually so needed in many homes.

While humidifiers and dehumidifiers sound very similar, they actually serve two very different functions.

Your home will only need one product or the other, but sometimes it’s difficult to know which one.

To find out the true functions and benefits of humidifiers/dehumidifiers and how to know which one is right for your home, read on!


Function of A Humidifier Vs Dehumidifier

Humidifiers and dehumidifiers serve opposite functions in the home.

They are both used to control humidity levels, but one adds humidity and one removes it.

Each machine uses a humidistat to monitor humidity levels in the home to keep them within a healthy range; they measure relative humidity, which is a representation of how much humidity is in the air compared to how much COULD be at the current air temperature.

Let’s take a look at which machine serves which function (you can probably guess from their names) and how they work.


humidifier review

Humidifiers are designed to add moisture to the air to combat low humidity levels.

Many types of humidifiers will also end up adding some warmth to the air as well since they generate hot mist, but there are cool mist humidifiers as well that will only add moisture.

This type of humidifier is the best for homes with pets and children in order to prevent accidental burns from occurring.

Humidifiers will require you to add water to a tank regularly; depending on the humidity level in your home when you start the machine, it may use up the water quite quickly.

Humidifiers work by creating mist: there are a number of different methods for them to do this, but they will all turn water in the tank into water vapor that will circulate throughout the space.

Increasing the moisture in the air will increase the humidity. Warm mist humidifiers are more commonly used in the winter months since they warm the air as well.

Some humidifiers have a diffuser built in that allows you to add essential oils and create some more positive effects in your home.

These aren’t as common as standard humidifiers that lack this function, such as impeller, ultrasonic, and evaporator humidifiers, but they are all beneficial.



Dehumidifiers serve the exact opposite function of humidifiers; rather than adding moisture to the air, dehumidifiers remove it.

High humidity is just as damaging as low humidity, so each machine can be essential to the health of you and your home.

Dehumidifiers are more commonly used in the summer months since the warmth outside tends to generate higher humidity in the home, but they can be used all year round.

In the warmer months, the use of a dehumidifier can actually lessen the demand on your air conditioning unit since they also cool the air.

Dehumidifiers control indoor humidity by pulling in room air with a fan, condensing the water, and then sending the dry, cool air back into the room.

Since dehumidifiers will collect water as they decrease the levels of water vapor in the air, you will need to remember to empty the water tank rather than fill it as you would with a humidifier.

The main types of dehumidifiers you’ll see on the market are desiccant dehumidifiers and compressor/refrigeration dehumidifiers.

These are both portable machines and have their own pros and cons.

Whole house dehumidifiers also exist (ones that are built right into your HVAC system) but they are more expensive and more of a hassle to install and maintain.

As a result, most people opt for the standard portable style dehumidifiers.


Can Both Humidifiers And Dehumidifiers Work With An Air Purifier?

air purifier

In short, the answer is yes.

Both humidifiers are dehumidifiers are perfectly compatible with an air purifier, and they can actually improve functionality of an air purifier and the efficiency of your HVAC system.

With a humidifier or dehumidifier controlling the humidity levels in a space, an air purifier can function more effectively.

Dehumidifiers can actually perform some purification of the air as well, as a passive effect of condensing the moisture in the air and removing water vapor; any contaminants trapped in the water vapor will also be removed from the air.

One note to make about using a humidifier with an air purifier is that the humidifier should only be filled with pure water like distilled water.

While this is a general rule that everyone should follow, it is even more important when using an air purifier because non-pure water has the potential to send pollutants back into the air and make your air purifier work even harder.

Since dehumidifiers make the air a bit cooler and humidifiers warm the air to a small degree, your heater and air conditioner won’t have to work as hard to maintain the temperature in your home.

This will save you some money on electricity and also reduce the need for maintenance and repairs.


Pros And Cons Of A Humidifier

humidifier review

Humidifiers are necessary products to improve the health and comfort of many homes, but that doesn’t mean they are perfect products.

Just like any other product, humidifiers come with their own set of disadvantages along with their benefits. Let’s take a closer look.


  • Can lower heating costs in winter months
  • Improve indoor air quality
  • Prevent illness and cracking wood floors
  • Improve the lifespan of furniture


  • Can grow mold if you don’t use distilled water and clean the tank often
  • Will be damaged if the tank runs dry; requires regular monitoring
  • Produce a fair amount of noise
  • Hot mist models can be dangerous


Pros And Cons Of A Dehumidifier


A buildup of moist air in the home can cause a lot of problems, and as we’ll see, dehumidifiers can have a number of positive effects. However, they also come with their own downsides.

The exact list will vary depending on the model type you get and conditions in the room and surrounding areas of the home, though.


  • Can lessen the impact of allergens
  • Can make the air feel more comfortable
  • Slight air purifying effect
  • Can help your air conditioner run more efficiently


  • Requires regular tank emptying
  • Has the potential to create too much dryness and overly low level of humidity if not self-regulated
  • Not all models work in low temperatures
  • Can be quite noisy


Do I Need A Humidifier Or Dehumidifier?

There are a number of signs you can look for in your home and in terms of personal health and comfort that will tell you whether a humidifier or dehumidifier is right for your home.

Some symptoms of dry air will be the same as those seen with overly humid air, but in general, these two states are very easy to distinguish inside your home.

Signs You Need A Humidifier

  1. Dry skin and/or itchy skin
  2. Static electricity throughout the home
  3. Congestion or bleeding in nasal passages
  4. Your hygrometer shows consistently low readings
  5. You get frequent colds or sinus infections
  6. Wood floors or furniture are drying out
  7. Worsening asthma

Signs You Need A Dehumidifier

  1. Condensation (water droplets) on windows and doors
  2. Mildew or mold growth
  3. Blistering/peeling paint
  4. Musty odor in the home
  5. Heavy-feeling air
  6. Excessive allergy symptoms
  7. Wet/rotting wood


Leave a Comment

* By using this form you agree with the storage and handling of your data by this website.