How Does a Cool Mist Humidifier Work? (Evaporative, Ultrasonic, Impeller)

A humidifier is a great product to add moisture to home, particularly during the winter when the air is dry. As the model getting smaller and smaller, have you ever wonder how does a cool mist humidifier work flawlessly every time? There is no huge motor fan and advanced technology to support the humidification. All you get is a big reservoir that converts the filled water into vapor. Also between evaporative, ultrasonic, and impeller type, what are the differences and how does each work? Out of the three, which humidifier is the most effective in distributing moisture?
Short answer
All cool mist humidifiers will release room-temperature mist through various technologies.


Types of Cool Mist Humidifiers

Before we go deeper on how do cool mist humidifiers work, there are 3 common types in the market. They are evaporative, ultrasonic, and impeller humidifiers. Each type will have a unique set of technology with its own advantages and disadvantages. They also vary in pricing, effectiveness, and maintenance needed. If you are looking for a compact humidifier to improve sleep, alleviate cough, sinus, and asthma, anyone of the cool-mist will do.

How Do Evaporative Humidifiers Work?

An Evaporative humidifier uses an internal fan to pull air into the unit. The air will have to flow pass a saturated wick filter absorbing water through the reservoir. The now damp air will be propelled out into the room air stream. The cycle will continue until the humidity level has reached the desired point. Because evaporative humidifier does not use heat to circulate moisture, it is safe for everyone including baby. The upside of using evaporative is the cheaper price tag and less white dust discharge than an ultrasonic humidifier. The downside is regular cleaning is needed on the wick filter to prevent mold and bacteria growth in the bucket. You can reduce the mineral buildup in the appliance by refilling with only distilled water.

How Do Ultrasonic Humidifiers Work?

An ultrasonic humidifier uses a piezoelectric transducer/ ceramic diaphragm that oscillates at an ultrasonic frequency to create water droplets. As the plate vibration speed increased, the water droplets will not be able to hold on to the surface and force to exit as the form of water vapor. The dissipated tiny mist (about one micron in diameter) will then be absorbed into the air. Ultrasonic humidifiers are safe as the generated high frequency does not pose any health risk to the users. The benefit of using ultrasonic humidifiers is the environmentally friendly aspect as it does not use any filter. It is also the most silent compared with evaporative and impeller humidifier. However, an ultrasonic humidifier will have higher gray and white dust deposits internally than evaporative. Hence you should only use demineralized water to reduce the amount of white dust from spreading across the room.

How Do Impeller Humidifiers Work?

An impeller humidifier uses a rotating disc that flings water through a diffuser. The running diffuser will then break water particles into fine droplets. The water droplets will then release into the air in the form of a mist. Like evaporative and ultrasonic, impeller humidifiers are very safe and used in other appliances. It is also inexpensive given it is simple technology with no complicated parts. Most impeller humidifiers will cover a wider range of humidification than other types. The bad is of course, the clearly audible mechanical noise from the rotating disc. Only use distilled water that will help reduce the spread of microbes and germs during the whole humidification.

So Which Type of Cool Mist Humidifier Should I choose?

There is no wrong in picking either one of the humidifiers. If I’m on a budget constraint, I would opt for an evaporative humidifier as it is cheaper by 10-50 dollars. If I want a complete silent model for bedroom use, I would go with the pricier ultrasonic humidifier with less maintenance needed. If I want an easier to clean humidifier with fewer mineral residues, again go with ultrasonic or impeller. Ultimately, a humidifier is there to increase the dampness level in a room and all cool-mist types will be able to achieve that. Focus on the brand reputation, availability, reliability and durability instead.

In this post, we will only focus on the benefits of using cool-mist humidifiers. First off, the increased humidity will moisture your skin and reduce common allergies including cold. It will also make breathing much comfortable especially if you have a baby at home. Cool mist humidifier in general is cheaper, uses less electricity, and covers more grounds than a warm-mist type. It is also much safer over warm mist because if you have little one or pets, the expel mist will not cause any burn.



Max Fernandez

A humidifier distributor with more than 11 years of experience in the field, Max Fernandez is no stranger to the moisture-capturing machine. You can catch him here reviewing humidifiers and preaching on the importance of perfect humidity.