Types of Humidifiers

Purchasing a humidifier is an important decision and one that can go wrong for a variety of reasons. When looking for the best system for your home, the first thing to consider is the type of humidifier. There are close to a half-dozen types of humidifiers currently available on the market and two different classes to consider as well.  

Humidifier Classifications

Dehumidifiers and humidifiers have a lot in common, even if they serve an entirely different purpose. They are both classified into two different categories, which means there are smaller machines that can handle a few rooms along with whole-house systems that range from 1,000 to 4,000 square feet or more.

Standalone Humidifiers

Often called single-room humidifiers, these residential systems will be the most familiar to homeowners. They are built to handle one or more rooms in a home and are often rated from 250 to 1,000 square feet.

Manufacturers also categorize these systems by the type of room, so it’s not uncommon to see nursery humidifiers or travel-sized alternatives. Regardless of the size, these are the types of humidifiers you’ll find available in the standalone class.

Cool Mist Humidifier

Cool Mist Humidifier

Whenever you hear a manufacturer refer to their humidifier as a cool mist system or an evaporative humidifier, it means the water isn’t heated before it’s turned into a mist. Instead, these systems use a wick that draws moisture into the machine where it’s dispersed with the help of a fan.

They are one of the cheapest types of humidifiers and come in the widest variety of sizes. That means you’ll also find more features in this class, including the ability to add inhalants during flu season or if you simply have bad sinuses.


  • Easy to use
  • Low operating cost
  • Solid selection of features and sizes
  • Produces no heat, so it’s safe to use around children


  • Potential for bacteria buildup
  • Noisier than other styles

Warm Mist Humidifier

While a cool mist humidifier is ideal for some situations and can help you breathe easier, a warm mist humidifier is ideal for winter weather. Also known as steam vaporizers, these budget-friendly systems put out a fine warm mist throughout a room.

Warm mist humidifiers heat or boil the water inside, which prevents bacteria from building up. As there is no fan, they are also quieter than a cool mist humidifier. Because of the heat, they aren’t the best option if you have pets or children in your home.


  • Comfortable to use in cold weather
  • Quiet operation
  • Good range of features
  • Less chance of bacterial contamination


  • Not the best option for homes with children or pets
  • Limited size range

Ultrasonic Humidifier

An ultrasonic humidifier is unique and uses a nebulizer to disperse moisture throughout a room. The nebulizer has a small diaphragm that vibrates at high speeds, similar to a speaker. This helps create a fine mist, which is then distributed through the air.

Ultrasonic Humidifier

Ultrasonic humidifiers are quiet, effective, and some models can heat up the water or keep it cool. They are more expensive, and mineral dust can be an issue if it’s a cool mist system. As they are considered premium humidifiers, there are some interesting features in this class as well.


  • Efficient and highly effective
  • Machines that can do hot and cold mist
  • Quiet operation
  • Easy to maintain


  • Can be expensive
  • Potential for bacteria and mineralization

Air Washer

Boneco W200 Humidifier Air Washer

Boneco W200 Humidifier Air Washer

These systems are fairly new to the industry and live up to their namesake by washing the air while humidifying a room. An air washer is larger than most standalone systems and built to cover larger areas. Most use a series of rotating discs to scrub the air before returning it to a room, which makes them ideal for homeowners with allergies.

As an air washer is a 2-in-1 humidifier, there’s a bit more maintenance involved and more parts that can falter as well. These systems are quiet and often have multiple speeds, but not as many features as you’ll find on a high-end single room humidifier or a dedicated air purifier.


  • Can clean and humidify the air
  • Covers areas between 200 to over 1,000 square feet
  • Extended runtimes
  • Better warranties


  • Price compared to a traditional humidifier

In addition to Ultrasonic, Cool Mist, and Warm Mist humidifiers, there are also vaporizers and hybrid humidifiers to consider. Vaporizers are similar to steam-based humidifiers or warm mist systems as they use heat to create a mist and are often used with inhalants or essential oils, just like a hybrid humidifier. These systems can humidify while diffusing or purifying your air. These come in many forms, including some units that look more like a piece of art than a humidifier.

Whole-House Humidifiers

Honeywell Home HE360A1075 HE360A Whole House Humidifier

When you need to humidify large areas or even your entire home, a portable system usually doesn’t cut it. That’s where whole-house humidifiers come into play, and there are several variants of these systems as well with flow-through, steam, and bypass or drum humidifiers.

A drum or bypass humidifier has a drum with a pad that soaks up water from a reservoir inside the tank and releases it into the air. While they work well and don’t require a drain, the standing water in the reservoir is prone to bacteria.

Flow-through humidifiers are installed in a similar fashion and make use of your HVAC system or ductwork as well. While you’ll need a steady supply of H20 or a drain for some of these systems, maintenance is easier as the buildup of mold and bacteria won’t be a problem.

A whole-house humidifier that uses steam can provide humidity across a large area faster, but they are more expensive and cost more to run as well.  Some of these systems are ductable, while others can take on familiar form factors or blend right in with the furniture in your home like console humidifiers.

The main thing to keep in mind with a whole house system regardless of its size is that they are larger and more can be considerably more expensive than smaller systems. You’ll want to consider placement beforehand, and possibly a professional to install the unit depending on the system.

Humidifier FAQ

Q: What size humidifier do I need for my home?

A: Humidifiers are classified by room size, so the easiest way to narrow the field is to know the square footage of the affected room or area. Those numbers are just a guideline, however, and factors like placement and how well a room is sealed come into play as well.

Q: What causes white dust from humidifiers?

A: Whenever you see whit dust around a humidifier, it’s because of minerals in the water. It’s not an issue with steam-based systems, but common with cool mist humidifiers and ultrasonic systems. Demineralization cartridges are one way to remedy the situation, but using distilled water can also solve the problem.

Q: Is it safe to use essential oils in a humidifier?

A: While it all depends on the type of humidifier, most manufacturers do not recommend using essential oils. They can break down the materials in your water tank and cause problems on the inside of your system as well.

Q: What style of humidifier is the quietest?

A: For a single room or small area, an ultrasonic humidifier is often the best option when noise levels are a concern.

Q: How often should I replace the wick or filter in my humidifier to prevent mold or bacteria?

A: On average, you should expect to change the wick once a month, although the length varies by model.

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