Humidifier vs. Dehumidifier: What’s the Difference?

Humidifier on a table inside a home

Do you experience breathing difficulties, skin problems, or allergy aggravation in your home and wonder why? They may be consequences of indoor humidity above or below levels recommended by the U.S. Environmental Protection Agency. Mold growth, which is common when it’s too damp inside, can worsen these symptoms.

Seasonal changes in humidity and indoor heating and cooling make it challenging to keep your home’s humidity at a comfortable level. Without consciously regulating your indoor air humidity, you’re likely to encounter wide swings from overly dry to abundantly moist air.

To maintain a comfortable indoor humidity level, you may need a humidifier or a dehumidifier. But which one is better and which one do you need? Could they both have places in your home strategy to regulate indoor humidity?

In this article, discover the differences between a humidifier vs. a dehumidifier. Find out which is better for your particular situation.

What’s the Difference Between a Humidifier and a Dehumidifier?

A humidifier adds moisture to the air (increasing the relative humidity) when it is too dry. While a dehumidifier removes moisture from the air (decreasing the relative humidity) when it is too humid.

Figuring out what unit you need in your particular situation partly depends on the time of year. In winter, a humidifier can be a lifesaver. But in the summer, a dehumidifier is your best friend.

Then again, if you rely heavily on air conditioning for summer cooling, a humidifier will save the day again, as air conditioners can remove too much moisture from the air.

The U.S. Environmental Protection Agency recommends an indoor humidity level below 60% and ideally between 30-50% for homes and offices. Using this metric as a guideline, it’s easy to determine whether you need a humidifier or a dehumidifier, when you should operate it, and for how long.

By setting the appliance’s built-in humidistat at the suggested percentage—and confirming it with an indoor hygrometer—you’ll be able to breathe easier knowing you’re within the recommended range.

When to Use a Humidifier

Humidifier running in a living area

Humidifiers are commonly used during the winter when home heating makes indoor air overly dry. Sometimes, summer air conditioning could remove too much moisture from your airspace while cooling your home. In that case, a humidifier can also help in the summer.

Whether you’re using a humidifier in winter or summer, the goal is to alleviate the unpleasant symptoms of dry air. These include:

  • Dry skin, mouth, and eyes
  • Chapped lips
  • Breathing difficulty
  • Flaky scalp (dandruff)
  • Nosebleeds
  • Sinus headaches

Benefits of Using a Humidifier

If your home’s air is below 30% relative humidity, and it’s affecting your sleep, any skin conditions, or causing respiratory condition flare-ups, then a humidifier could help alleviate your symptoms. Here are a few specific health benefits of humidifiers.

  • Natural moisturizer. Prevent cracked lips, flaky skin, and fragile hair by adding moisture to your home air.
  • Respiratory symptom control. Wetter air reduces shortness of breath associated with bronchitis or colds. The added moisture in the air makes coughing up phlegm easier.
  • Natural sleep aid. The enhanced lubrication of nasal and sinus passageways from moist air makes breathing easier and snoring less likely in people with sleep apnea.

Types of Humidifiers

There are four major types of humidifiers on the market today. Here’s a brief rundown:

1. Ultrasonic Humidifiers

High-frequency vibrations in the water reservoir create a visible mist that is transmitted through your home’s airspace. Ultrasonic humidifiers don’t need noisy fans to operate. They are super quiet when running, making them an excellent bedroom option.

2. Evaporative Humidifiers

A wick filter draws up water, and a fan blows dry air through the filter. Water evaporates into the air. The moist air circulates in your home.

3. Steam Vaporizers

A heating element boils water, creating steam that cools inside the unit before entering your room as a warm mist. Steam vaporizers can be dangerous for kids because of the burn risk.

4. Whole-House Humidifiers

The humidifier is connected to your home’s central heating, ventilation, and cooling (HVAC) system. Moistened air travels throughout the ductwork equally to all parts of your home.

Note: Ultrasonic and evaporative humidifiers are collectively called cool mist humidifiers to distinguish them from steam vaporizers.

We recommend buying a large cool mist humidifier capable of humidifying a sizable area or your whole house. Read our buying guide here to find a suitable model.

When to Use a Dehumidifier

Woman removing water from a dehumidifier tank

Dehumidifiers come in handy during bouts of high humidity typical of hot and steamy summers. When the air feels heavy, and the relative humidity percentage exceeds 60%, or you see condensation on indoor surfaces, you’ll know it’s time to turn on the dehumidifier.

Benefits of Using a Dehumidifier

When too much moisture in the air creates or worsens health issues, a dehumidifier is essential for eliminating moisture. Here are a few benefits of using a dehumidifier.

  • Mold growth regulation. Mold flourishes in a home when the humidity is above 60%. A dehumidifier keeps the microorganisms and the toxic substances they produce in check.
  • Musty odor reduction. Microscopic airborne mold spores get activated and reproduce when it’s too damp inside. This means more pungent musty odors. A dehumidifier lowers the amount of moisture in the air, so there will be fewer smelly mold spores floating around.
  • Dust mite allergy control. Dust mites thrive when the indoor humidity is over 55%. A dehumidifier will nip them in the bud.
  • Cooling effect of drier air. Indoor humid air makes the “real feel” temperature higher than it really is. A dehumidifier negates this effect. As a result, you won’t need to run the AC as much, so you’ll save on energy costs, too.

Types of Dehumidifiers

There are three main types of dehumidifiers commercially available today. Below is a basic description of each kind.

1. Refrigerant (Compressor) Dehumidifiers

Like a household refrigerator, a compressor dehumidifier draws in humid air that passes over coils containing a refrigerant (coolant chemical). Water droplets condense from the air and drip into a storage tank. The dehumidifier releases drier air into the home environment.

2. Desiccant Dehumidifiers

Rather than cooling incoming air, a desiccant dehumidifier sends it over a rotating wheel containing a moisture-absorbent material known as a desiccant. As droplets form, this dehumidifier channels them into a storage tank while it transmits drier air back into your home.

3. Whole-House Dehumidifiers

High humidity levels are usually a problem in basements and crawl spaces. However, if excess moisture is a problem in your entire home, then a whole-house dehumidifier may be the best solution. It attaches to your central HVAC system and functions like a refrigerant dehumidifier. Dehumidifying the air as it flows through your air ducts.

Key Takeaways on Humidifier vs. Dehumidifier Differences

Seasonal variations in outdoor humidity and indoor heating and cooling use cause home humidity levels to fluctuate widely. Air that is too dry or too damp can adversely affect your health. To maintain the EPA-recommended indoor humidity level of 30-50% for a healthy home, you may need a humidifier or dehumidifier.

Knowing the differences between humidifiers and dehumidifiers is essential before investing in one or both of them. A humidifier will add moisture to the air when you need to raise the humidity in your home. In comparison, a dehumidifier will remove excess moisture from the air when your indoor humidity level is too high.

With either a humidifier or dehumidifier, you’ll breathe easier in your home, no matter the seasonal variability of humidity or your use of home heating and cooling throughout the year.

Published: December 7, 2022

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