Types Of Humidifiers: Comparison Of Pros And Cons

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The indoor humidity level is one parameter you cannot afford to overlook when trying to build your perfect home. Maintaining a good humidity level in your home is critical for comfort and neglecting it may cause some problems that can damage your home and spoil your health.

The ideal humidity level you should aim for is between 40% to 60% for optimum health benefits. However, during the colder and drier seasons, this level can be difficult to achieve. There are numerous easy ways to humidify your home naturally but sometimes a humidifier is your best choice for the predictable and powerful humidification it can put out.

When choosing your home humidifier, you might hear many different terms such as warm mist, cool mist, vaporizer, evaporative, impeller etc. You might see some of these terms being used interchangeably or you might read articles that seem to contradict each other. Essentially, the information is just a huge mess and you end up being more confused than before.

Frustrated with the confusing information I could find, I did a comprehensive research of the types of humidifiers and crystallized it into something easy for homeowners to read and understand. In this article, you will read about the types of humidifiers and a comparison of their pros and cons. From there, you can decide what is the best type of humidifier you need for your home.

If you are in a hurry, check out the humidifier comparison table below for a quick overview!

Comparison Chart Of Different Types Of Humidifiers

Air Washer
Mode of humidificationEvaporation UltrasonicSteamEvaporation
Cool/Warm MistCoolCan be bothWarmCool
Contains fanYesNoNoSometimes
Contains filterYesSometimesNoNo
Comparison Table Of Types Of Humidifiers

Types of Humidifiers

There are 4 main types of humidifiers

  • Evaporative
  • Ultrasonic
  • Vaporizer
  • Air washer

Evaporative Humidifier

In essence, evaporative humidifiers work by evaporation of the water in the humidifier and releases it as a cool mist. Inside most evaporative humidifiers is a wick that absorbs the water in the humidifier. A fan then evaporates the water in the wick giving us water vapor and increasing the humidity in the room. For those who are unfamiliar with what a wick is, it is a porous cylindrical structure that has a large surface area which allows maximum water absorption and water evaporation (my son thinks it looks like a beehive). 

Example of a wick filter used in humidifiers

The wick also acts like a filter to filter out any impurities or contaminants in the water being used in the humidifier. Due to the presence of this wick filter, the type of water used in an evaporative humidifier is less restrictive than an ultrasonic humidifier which does not use a filter. Generally, you can use normal tap water in an evaporative humidifier without any issues. Wicks are usually quite large in size and therefore you will find that most evaporative humidifiers are bulkier in size and also heavier.

Another advantage of evaporative humidifiers is that it can never over-humidify the air because it works by evaporation. If the ambient air is already saturated with water, evaporation will not be able to occur no matter how much the fan blows at the water. 

Example of an evaporative humidifier

The purchase cost of an evaporative humidifier is usually the lowest among the different types of humidifiers but the operating cost is the highest from the replacement of wicks and filters. It is recommended that filters be replaced every 3 to 6 monthly depending on the usage of your humidifiers. Different humidifiers may also have different recommendations so it would be best to check in with the manufacturers if you are intending to get an evaporative humidifier.

Evaporative humidifiers also tend to be louder due to the running fan that is used to evaporate the water in the humidifier. Some humidifiers can register noise level up to 50 dB at their highest speed settings. If you are intending to use your humidifier in your bedroom or if you are very sensitive to noise then an evaporative humidifier may not be for you.

Ultrasonic Humidifier 

An ultrasonic humidifier is a nebulizer that uses high frequency vibrations to break water down into ultra-fine droplets which then get released into the air as a mist. Depending on the specific model, the mist may be a cool mist or a warm mist. An easy way to see if a humidifier is an ultrasonic humidifier is to see if there is a mist plume coming out from the model. If there is a mist plume, it is usually an ultrasonic humidifier. 

An ultrasonic humidifier does not have a wick like an evaporative humidifier and typically does not have any filter as well. As such, they are usually less bulky and lighter. However, because of the lack of a filter to absorb impurities and contaminants, it is recommended to use either distilled water or filtered water in the humidifier. If hard water such as tap water is used, ultrasonic humidifiers may dispel white dust into the air due to the mineral contents in the water. 

Ultrasonic humidifiers have the highest humidity output among all the types of humidifier because it actively breaks down water into fine droplets and forcefully discharges it into the air. Theoretically, there is the risk of over-humidifying the air but most humidifiers have an inbuilt humidistat to prevent that from happening.

Example of an ultrasonic humidifier

Ultrasonic humidifiers do not use a fan in its operation and quietness is one of their main selling points. Ultrasonic humidifiers rarely register noise levels beyond 35 dB and are great for use in bedrooms, baby’s room and study rooms. However, after prolonged usage, ultrasonic humidifiers may shake a bit and hence make some noise. When that happens, it may be time to consider a change.

In terms of price, ultrasonic humidifiers usually cost more upfront but have the lowest operating cost because there is no need for filter replacement every 3 to 6 months. 


Vaporizer humidifiers basically boil the water in the humidifier into steam before releasing it into the air. As you can probably imagine, the mist from a vaporizer can get quite hot and hence it is also known as a warm mist humidifier. Vaporizer or warm mist humidifiers are very popular among homeowners suffering from allergies or asthma because the warm mist usually has a more soothing and comforting effect on sensitive airways than cool mist humidifiers. 

Due to the heating of the water in the vaporizer, most bacteria in the water are also eliminated and the mist coming from these humidifiers are generally cleaner and healthier compared to an ultrasonic humidifier. 

Example of a vaporizer

For homeowners who are into aromatherapy, you will be glad to know that most warm mist humidifiers contain a medicine cup or reservoir  for the incorporation of essential oils into the mist. However, do not confuse  vaporizer/warm mist humidifier with a diffuser. A diffuser is an appliance that converts essential oils into tiny droplets of oil that are dispersed directly into the air. A humidifier can sometimes act as a diffuser but a diffuser can not humidify a room. 

Vaporizers/warm mist humidifiers generally do not have a fan and are also very quiet during its operation. However, homeowners will generally want to refrain from using these in a baby’s room or kid’s room due to the boiling water that is in these humidifiers. If they are accidentally knocked over and lands on the child, nasty burns are certain to happen. 

 Air Washer

Air washers are 2-in-1 appliances that combine a humidifier and an air purifier together in one unit. Besides being able to control the humidity in the air, air washers also clean the air by filtering large particles, pollen and contaminants from the air. With a combination of these two functions, the indoor air quality in your house will be maintained at a comfortable and healthy level. For homeowners who are suffering from chronic allergies and asthma, air washers may be your best bet yet.

Air washers work by using a series of spinning discs to filter out allergens and particles from the air as air is drawn into the unit. The discs then spin the water through a special filter that breaks it down into a fine mist that gets released into the air. For some models, the water vapor is created using evaporation before being released.

Example of an air washer

Depending on the models, air washers may contain fans and some do get quite noisy. Therefore, air washers do tend to be bulkier than normal humidifiers due to the discs in the unit. Because of the added feature of air purification, the upfront cost of an air washer is also the highest among all the other types of humidifiers.

What Is The Ideal Indoor Humidity?

A good humidity level is one in which we can get the most amount of comfort and where it is most conducive to our health. There is a wide range of ideal indoor humidity reported by studies and online sources but most seems to agree that a comfortable humidity level is between 40% to 60%. 

In terms of health, this level of humidity is also considered to be the most optimum for health. The survival and infectivity of airborne transmitted bacteria and viruses are minimized by exposure to relative humidity of 40% to 60%. This greatly reduces the risk of disease transmission from these pathogens.


Where Is The Best Place To Put Humidifier At Home?

For those in a hurry, these are the pertinent findings from our research on where to place humidifier in the house

  • Placement in the middle of the room leads to fast and even humidification
  • Keep humidifier 14 -17 feet (4-5m) away from walls and furniture
  • Place 3 feet (1 m) away from the bed 
  • Elevate the humidifier 2 feet off the ground
  • Keep the windows and doors shut when using the humidifier
  • Avoid running a humidifier and air purifier in the same room
  • Avoid placing humidifier in direct sunlight

If you want the full story, check out our guide here where we interviewed industry experts to find out the best place to put your humidifier at home!

best place to put humidifier

Humidity and Your Health

The inappropriate indoor humidity levels can have both direct and indirect effects on your health and comfort. The direct effects are the result of the humidity on your body systems and workings while indirect effects result from the impact of humidity on viruses, bacteria, fungi and chemicals.

Direct Health Effects

These are probably effects that most of us have experienced before. When high humidity is combined with high temperature, our sweat finds it very difficult to evaporate as the air is already saturated with water vapor. Therefore, we generally end up feeling very hot and sticky resulting in visible physical discomfort. 

Conversely, in areas with very low indoor humidity (dry air), we tend to suffer from irritation of the eyes, nose, throat and skin. This is due to the drying of the surface membrane that covers these areas. Some common symptoms that may arise are nose bleeding and eczema. 

Indirect Health Effects

Many studies have found that humidity can increase the risk of allergies and infections in the respiratory system. This effect is likely caused by the growth of bacteria, dust mites, viruses and fungi caused by inappropriate humidity levels. In addition to that, relative humidity may increase the concentration of harmful chemicals in the air when water vapor reacts with chemicals in the air.  

For more information on how poor home humidity is damaging your health, check out our article here to find out more!

How To Measure Humidity

The easiest way to measure the relative humidity in your home is to use a hygrometer which is a humidity sensor or humidity monitor. Digital hygrometers are very readily available now and they determine the humidity by using a sensor to monitor an electric current that is affected by moisture levels. 

These digital hygrometers are often integrated into a climate monitor which measures multiple other parameters like temperature, air quality and noise levels.


Questions and Answers (Q&A)

Q: Is a humidifier the same as a diffuser?

A: No. A humidifier is usually a larger device meant for the purpose for increasing the water vapor content in the air. A diffuser is usually a smaller personal device used to diffuse essential oils for aromatherapy. There are some devices that can act as both.

Q: Is a humidifier good for asthma?

A: Yes and no. Asthma due to allergies may improve as the indoor humidity is maintained at the ideal level of 40% to 60%. However, a humidifier may also breed mold and fungi if it is not cleaned regularly. A dirty humidifier may release more allergens into the air and aggravate asthma.

Q: Is it advisable to run a humidifier and an air purifier together in the same room?

A: No. The moisture from the mist coupled with the residues in the filter may become a breeding ground for mold and fungi if the filter is not maintained regularly. You can read this guide on humidifier placement to learn about other do’s and dont’s of humidifier usage.

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