Interior Home Technology

Ultrasonic vs. Evaporative Humidifier: Which is Best for Your Home?

Find out the key differences between ultrasonic and evaporative humidifiers to determine which is the right fit for your needs.
Deirdre Mundorf Avatar
ultrasonic vs evaporative humidifier

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Humidifiers help increase the moisture content in a room. For many people, using a humidifier is a terrific way to to combat dry skin and lips, and reduce congestion and other cold and flu symptoms, especially during dry winter weather. There are two main types of room humidifiers: Warm mist humidifiers require hot water to produce water vapor. Cool mist humidifiers is considered a safer alternative since it does not require the use of boiling water.

There are two types of cool mist humidifiers: ultrasonic and evaporative. While they are both cool mist humidifiers, each type works in very different ways to produce water vapor and increase the humidity in a room. Learning the ultrasonic vs. evaporative humidifier differences makes it easier to decide which type is best for your home.

Ultrasonic humidifiers employ high-frequency sound vibrations to emit fine mist into the air.

“How do humidifiers work?” is a question that many people ask as they shop for the best humidifiers for their homes. One of the key differences when you’re comparing vaporizer vs. humidifier is the way water vapor is made in each type of unit. Unlike vaporizers and warm mist humidifiers that boil water to make steam, ultrasonic humidifiers do not have a heating element and are considered a type of cool mist humidifier.

But what is an ultrasonic humidifier, exactly? These humidifiers expel an ultra-fine mist into the air through the use of high-frequency sound vibrations of the two inner ceramic plates. After the tiny water droplets are released into the room, they evaporate. As they continue to release into the room, they increase the humidity in the space.

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This ultrasonic humidifier offers up to 25 hours of constant quiet operation with its 1.5-liter tank. The 360-degree nozzle and two speed settings work together to ensure that the ideal amount of mist is released into the room to match your humidity needs. The humidifier also features a night light setting and automatic safety shut-off feature.

ultrasonic vs evaporative humidifier

Evaporative humidifiers utilize a wick or filter with a fan to introduce water vapor into the air.

While also considered to be a cool mist humidifier, evaporative humidifiers work quite differently from ultrasonic humidifiers. They rely on the basic principles of evaporation to increase the moisture content in a room. When you place a large bowl of water in a room, the water will evaporate and make the room more humid.

Evaporative humidifiers speed up this natural process of evaporation by using a fan and a wick filter. The fan in the humidifier pulls in air and blows it through the wick filter at the humidifier’s base. This causes the water to evaporate and turn into water vapor. The water vapor is then pushed into the room to increase its humidity.

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With its 2-gallon tank, this evaporative humidifier can increase the humidity in spaces up to 1,200 square feet. Its large capacity allows it to operate for up to 50 hours before the tank needs to be refilled. The humidifier offers four fan speeds, digital controls, an auto shutoff feature, and indicator lights for refilling the water tank and cleaning the filter.

ultrasonic vs evaporative humidifier

Ultrasonic humidifiers tend to be more aesthetically pleasing.

When considering a humidifier room strategy and aesthetic appeal, many people prefer the look of ultrasonic humidifiers. While evaporative humidifiers are generally bulkier since they have to hold a fan and a filter, the humidification device of an ultrasonic humidifier is much more compact. Those looking for a small humidifier will typically have a much easier time finding an ultrasonic model than an evaporative model.

Ultrasonic humidifiers sometimes have other bells and whistles, such as built-in clocks or colored LED night-lights, that add to their aesthetic appeal.

RELATED: Buyer’s Guide: The Best Humidifiers for Large Rooms

Ultrasonic humidifiers can disperse minerals and other contaminants into the air.

Because ultrasonic humidifiers don’t have a filter, any minerals or contaminants that are in the water that’s used to fill their tanks will also be released into the air. Calcium, magnesium, potassium, and other minerals are all commonly found in tap water. These minerals are released as gray or white dust that may settle on the flooring or furniture in the space. How much dust gets released can vary based on the water used. For example, hard water has a higher mineral content, so it can yield more dust.

Are ultrasonic humidifiers safe to use? The EPA says that “the possible health effects resulting from the dispersal of microorganisms and minerals by home humidifiers are not fully understood,” and recommends using distilled water to fill an ultrasonic humidifier’s tank. Distilled water still contains some minerals, but at a much lower concentration than tap water. Using distilled water not only reduces the amount of gray or white dust released by a humidifier, it will also decrease mineral deposits and scale inside the humidifier. Without regular cleaning, the humidifier’s insides can become a breeding ground for bacteria and microorganisms. For this reason, the EPA also advises unplugging, emptying, and thoroughly cleaning ultrasonic humidifiers regularly.

Evaporative and ultrasonic humidifiers require regular maintenance.

The filter in an evaporative humidifier works to reduce the amount of mineral dust released. However, the presence of a filter also means that you’ll have to monitor and replace the filter regularly. How often a humidifier is used will impact how often you’ll need to replace the filter, but manufacturers usually recommend using a new filter every 1 to 3 months.

Both evaporative and ultrasonic humidifiers need to be cleaned regularly—and by “regularly,” the EPA means at least once every three days. This maintenance will help remove mineral buildup and prevent the growth of bacteria. White vinegar mixed with water can be quite effective for cleaning a humidifier, but be sure to consult with the care instructions for the specific model you purchase.

RELATED: How to Clean a Humidifier

Ultrasonic humidifiers are quieter than evaporative humidifiers.

As their name implies, ultrasonic humidifiers use sound waves with a high frequency. Human ears are not able to detect such a high frequency, which means that an ultrasonic humidifier is quiet. When you’re looking for the best humidifier for a bedroom, choosing an ultrasonic model will help ensure that your humidifier doesn’t disrupt your sleep.

While some evaporative humidifiers are louder than others, all evaporative humidifiers will produce some sound because they use a fan to help the water evaporate more quickly. The fan runs constantly, so models with a quieter fan will still be louder than an ultrasonic humidifier.

ultrasonic vs evaporative humidifier

Evaporative humidifiers tend to cost less than ultrasonic counterparts.

Evaporative humidifiers are typically less expensive than ultrasonic models. However, the price difference has decreased as ultrasonic humidifiers have gained popularity with consumers.

Beyond the initial cost of evaporative and ultrasonic humidifiers, there is also the cost of filter replacements to consider. While ultrasonic models do not require a filter, the filter in an evaporative humidifier will need to be changed every 1 to 3 months. Replacement filters are relatively inexpensive, but the cost can add up over several months or years of operation and may eventually negate any initial savings on the cost of the evaporative humidifier.