How to Choose a Humidifier

Date: 12-05-2013

It’s humidifier season and we know you’ve got questions, so here are the answers. In this ‘How to Choose a Humidifier’ overview, we will explain all of things you need to know before you buy. We’ll be covering humidifier sizes, the differences in mist types such as warm mist and cool mist and other features that will help you make the most informed decision when choosing humidifiers.


Ultrasonic: this humidification technology uses a metal diaphragm vibrating at a high-frequency vibration to generate a micro-fine cool or warm mist. A fan then blows the mist into the room where it immediately evaporates. These ultrasonic vibrations kill much of the bacteria and viruses by destroying their cell walls. Additionally, ultrasonic humidifiers are energy misers and are virtually silent while operating. In the past there were some disadvantages to ultrasonic humidifiers such as white mineral dust and the build-up of bacteria and mold in the tank. However, many of ultrasonic humidifiers like those offered by Air-O-Swiss or Stadler Form are equipped with demineralization cartridges and hydro cells to counteract these disadvantages.

Evaporative: an evaporative humidifier is equipped with a filter wick or pad which absorbs the water collected in the reservoir. A fan then pushes the cool moist air out into the room. Evaporative humidifiers are self-regulating and usually raise the humidity in the room quickly and efficiently. If you are worried about white mineral dust, then an evaporative humidifier is a good choice since it only delivers clean, invisible cool moisture into the air. Some disadvantages of an evaporative cool mist humidifier are the filter costs, the noise level on some of the high fan speeds and the threat of bacteria forming in stagnant water if not properly cleaned.

Air Washer Humidifiers: the beauty of an Air Washer is its ability to purify and humidify simultaneously without filters. Water in conjunction with rotating discs retain and remove large airborne impurities (such as dust, pollen and particle-bound odors) while returning clean, properly humidified air to the room. Air washers are extremely user-friendly and work on the self-regulating evaporation principle without additional controls systems to ensure optimal air. These systems are usually equipped with an Ionic Silver Stick which prevents microbial growth in the water base. They are also relatively easy to maintain since the discs are dishwasher safe and there are no filter wicks to replace.


There are a variety of sizes that meet the humidification needs for a single room, large areas and for travel or personal spaces. Each size offers a different level of performance. The performance level is sometimes referred to as a ‘gallon dispersion rating’ which is how much water is turned into a mist of humidity within one 24 hour period. Humidifiers can range in output from 1 to 14 gallons per day.

Each humidifier also offers its own coverage area. A coverage area is the maximum amount of square feet which a humidifier can operate effectively. However, room coverage recommendations should be used as a rough estimation when seeking the ideal humidifier. A manufacturer’s recommended room coverage is based on the maximum amount of moisture the humidifier is capable of producing per day when operating in perfect environmental conditions (for example, operating with the bedroom door closed and on its highest speed setting). Since everybody’s room environment and desired speed and output settings are different, it is generally recommended choosing a humidifier that provides the highest output possible for your particular room and budget.