How Humidifiers Work – 5 Hidden Facts You Never Knew Existed

Are you planning on buying a humidifier but you don’t know anything about them? Do you want to know how humidifiers work? Before I got my first unit, I turned the internet upside down so that I get much more familiar with how they work so that if needed, I would know what to check if it suddenly stopped working. Also, sometimes humidifiers start acting funky, become noisy, or start leaking. And, the first thing that usually comes to our minds is: “Oh, it’s broke… Now I need to pay for the service”.


However, in most cases, it is just a minor fix that can be done in like 5 minutes. And, there’s no need to pay for servicing it.

Humidifier Type

Energy saving

Best for

Easy to use


of Maintenance



During warmer months of the year

Extremely easy to use due to a small number of parts and the simple evaporation process

Medium – Regular cleaning of both the tank and the wick filter, and regular filter replacement

Ultrasonic (Cool Mist)


During warmer months of the year

Easy to use

Low – Only regular cleaning of the tank, and demineralization from time to time (depending on the water hardness)

Ultrasonic (Warm Mist)


During the winter months

Easy to use but you need to be careful  because it heats up

Medium – Regular cleaning and demineralization, which can be a bit complicated when it comes to the heating chamber

How Humidifiers Work – Types of Humidifiers

There are 3 general types of humidifiers. And, before choosing a specific type, get to know better each one of them so that you are sure you are making the right choice. Here is a short explanation for each type.


I will get much more in-depth with each type later.

Filtered Cool Moisture Humidifiers  (Evaporative)

Type of mist: Cool, invisible filtered moisture


When it comes to evaporative humidifiers, basically, they have a saturated piece of wick that filters out the minerals and evaporates.


This allows the vapor to be free of minerals and the infamous white dust that is associated with humidifiers.


To get that vapor out in the room, they use a fan that blows over the wick.


Now, since the vapor comes from the evaporating wick, it is invisible, unlike with other models where you can actually see the mist coming out.


The good thing about this type of humidifiers is that you simply cannot over humidify the room because the air in it, won’t accept more mist that it can absorb.


The only downside, but I really don’t consider this as a deal breaker, is the fact that you need to regularly replace the wick filter.

Filter Free Cool Mist Humidifiers (Ultrasonic)

Type of mist: Visible cool mist


The Ultrasonic humidifiers work with a different humidifying system when compared to the evaporative models.


They come with a nebulizer that breaks the water into a fine mist that is visible and pumped out in the air.


The nebulizer turns the water into a mist by vibrating at ultrasonic speed.


Unlike the evaporative humidifiers, ultrasonic models don’t have a filter.


But, this doesn’t mean the mist that comes out of the humidifier will be mineral rich because most models come with a demineralization cartridge, which traps the minerals from the water and stops them from entering the air in your home.


In case you buy a model without the demineralization cartridge, don’t worry.


You can use distilled water which is mineral free. In fact, using distilled water is highly recommendable for every type of humidifiers.


And, if you are perhaps interested in making your own distilled water, I have another post that explains how to make distilled water for a humidifier, at your home.


As for the noise level of this type of humidifiers, they are pretty much noiseless, or, produce a slight humming sound that in most cases doesn’t even disturb babies while sleeping.

Warm Mist Humidifiers

Type of mist: Warm visible mist


Now, unlike cool mist humidifiers that produce cool mist, as the name itself suggests, this type of humidifiers deliver a warm, visible mist.


They produce the mist by boiling the water in the heating chamber, which is then released into the air of your home.


The best thing about warm mist humidifiers is that, since they boil the water, the mist that comes out of them, is 99% free of bacteria.


Also, some models even include a special tank for adding medicine or aromatic oils, which gives added relief if you or your kids are sick and speeds up the healing process.


And, you can even cut down on the heating during the winter because these humidifiers raise the room temperature for a few degrees since the mist is warm.

How Humidifiers Work – Humidifier Types Breakdown

Finally, we’ve gotten to the part where I explain how each humidifier type works. We will start with the evaporative cool mist humidifiers.

Evaporative humidifiers

When it comes to evaporative humidifiers, its main characteristics are the use of a wick filter and a fan.


Without the mentioned two components, the humidifier would not be able to function properly.


The role of the wick (paper sheet or cloth) is to intake the water you pour in the tank, and then it evaporates, if the air in the room where the humidifier is located is dry.


The principle of the evaporative humidifiers is actually quite simple, once the wick is wet, the fan blows cool air on it and pushes the moisture out into the room.

Now, this also means that the moisture that enters the room’s air extracts the heat from the dry air, which is why when using a cool mist humidifier, the temperature in the room drops for a few degrees.


However, in case your home’s humidity levels are high (like it was the case with my home back in Germany), getting the moisture out of the wick can be nearly impossible when the fan is turned on.


But, we don’t usually use humidifiers if the air is nicely moisturized by mother nature, right?


So, why did I mention this fact? Well, this actually means that the evaporative humidifiers have a “self-operating humidity level system”.


Okay, not a system, really, but the fact is that if there already moisture in the air, the wick won’t evaporate, meaning you cannot over humidify the room.


Even though there are more than just a wick and a fan in a humidifier, parts wise, they are the most important ones for functioning and for the overall choice of humidifiers, based on your personal preferences.


But, I decided to talk about all the parts nevertheless and here they are.

Evaporative humidifier parts

When it comes to evaporative humidifier models, there are basically 3 main parts. They are the mentioned wick, the fan, and the water tank.

The Wick

The wick filter is a material that absorbs the water from the tank and then lets the moisture evaporate. This is possible thanks to its large area and the air coming from the fan.


It is in 99% placed in the center part of the humidifier base. And, its size can vary, depending on the size of the humidifier you choose.


The downside of using a wick filter is that it traps minerals (which is a good thing). But, the bad news is that it gets dirty relatively quickly.


This means regular checking and changing the filter. Which, furthermore, adds a slightly higher maintenance cost when compared to the rest of the humidifier types.

The Water Tank

how humidifiers work - water tank

The water tank or the reservoir is where you pour the water, and from where the water goes to the wick filter.


It is designed (in most cases, at least) to be easily removed, for either refilling or cleaning.


But, the most important thing to keep in mind when it comes to this part of the humidifier is that you will frequently be in contact with it.


This means that you need to wash it regularly because the bacteria on our hands can help with mold development.


Also, it is important to keep in mind that, when you are choosing the model of a humidifier, you need to know how “hard” are you going to use the humidifier.


For example, if you plan on using it for a smaller room and not that often, you can choose one with a smaller tank.


On the other hand, if you need to humidify larger areas, and do that often, the best thing would be to choose a model with the biggest possible tank, just so that you don’t end up spending too much time refilling it.

The Fan

This is the “humidity pushing” part of the humidifier, and it is placed right above the wick filter so that it can push the cool air through the wet wick and further into the air of your room.


The fan also allows for faster evaporation process and better distributes the humidity throughout the room.

What else is important to know about Evaporative Humidifiers?

Besides knowing how humidifiers work and which are the most important parts, there are a few more aspects that you should know before making the final humidifier type choice.



One of the things that makes choosing the evaporative humidifier so appealing is its cost.


You will notice for yourself that evaporative humidifiers are in most cases relatively cheaper than other types.


Why is that? Well, for one thing, it uses a replaceable wick filter that you need to change (read buy regularly).


And, that means additional expenses over the starting price of the humidifier.


Also, the main reason why they are cheap is the fact that they are extremely easy to build and use no more than 5 parts.


This cuts down the price of the manufacturing process and the final price of the product.


In the end, what you are paying for when buying an evaporative humidifier is a unit that needs regular maintenance, therefore, they can’t overcharge for it because no one would buy it.

energy efficiency

This type of humidifier is well known for being energy efficient.


This means that it can save you some pretty penny for the electricity bill in the long run.


And, remember when I said that the cool mist humidifiers bring down the room temperature by a few degrees when used?


Well, this also means that you won’t be needing to run your AC systems with full throttle, which means further saving on the electricity.


Just like anything else, if it carries water, it is susceptible to mold development.


That is why, for example, you need to regularly clean the wick so that it doesn’t allow bacteria to be developed on it and spread throughout the air in your home.


And, depending on your home’s water hardness, it should be replaced with a new one at least once a month.


In case this does happen, you should use mold and bacteria treatments.


Usually, I use a cartridge that prevents mold and bacteria growth. It is simply placed inside the tank, in the water.


Speaking of the tank, since it holds water, it needs to be cleaned regularly if you want to breathe healthy, bacteria and mold free air in your home.


Also, the same goes for any other part of the humidifier that is in contact with the water. They should be washed before and after use, and dried before storage.

Final Thoughts on the Evaporative Humidifiers

As you can see, evaporative humidifiers are relatively simple gadgets that actually have a lot to offer to your family and you.


It has 3 main parts and using it is a breeze. And, it is the most inexpensive type of a humidifier when compared to any other type.


When all that is taken into consideration, this type might be the best value choice when it comes to humidifiers.


It does need regular maintenance (changing the wick and cleaning), but other types require maintenance as well, and this type is the lightest energy consumer. So, keep that in mind.

Ultrasonic humidifiers (cool and warm mist)

If you read my previous posts, you know that Ultrasonic humidifiers (some models) can deliver both cool and warm mist.


Which, makes them very versatile and usable throughout the entire year, not just during the winter.


Now, how do they actually work? Well, they use high-frequency tech to hit the water with vibrations.


The water tries to “catch the beat” but thanks to its weight and mass, it is impossible and it starts “falling apart”.


This actually means that it breaks down into water droplets that end up as mist you see when you turn on the humidifier.


That mist is what cleans and humidifies the air in your room. And, it also cools down or warms up the temperature (depending on which type of mist you are using).

Ultrasonic humidifier parts

Unlike the evaporative humidifiers, which are simple and with a small number of parts, Ultrasonic humidifiers are more high-tech, come with more parts, and are generally considered better to be used for baby's nursery rooms as they are reliable and safe.


Here’s the breakdown:

The Water Tank

The name pretty much explains everything. This is the part that is in charge of holding in the water that is turned into mist.


Now, most newer Ultrasonic humidifiers come with a tank that also has a built-in sensor that notifies you when the water level in the tank is low, and when it’s time for a refill.


Also, this is the part that you will need to regularly clean so that mold and bacteria don’t develop.


The transducer, or as some call it the “nebulizer” is what turns water into mist. This is the part that vibrates at ultrasonic speed.


The simplest I can explain this is that you should look at it as a bass or a speaker membrane. You know how the membrane vibrates when there’s heavy bass in the song?


Well, the same happens with this part, only at a much, much higher speed.


As I explained earlier, once these high-frequency hit the water, it starts breaking into droplets because it cannot maintain its form, at such high-speed amplitudes.

Control Panel

This is the part that is practically the “brain” of the humidifier as it is in charge of all operations.


This system tells the transducer how fast or slow to vibrate when to switch from cool mist to warm mist (if your model allows it), when to start and when to stop.


And, this is where you should look for any other functions your humidifier might come with.

The Generator

The generator is the heart of the ultrasonic humidifier as it “feeds” the transducer with electrical energy.


This is also the part that transforms the high voltage to a lower voltage (depending on the humidifier model).


For example, if you would send direct 220V to the transducer, it would probably melt. The generator is there to make sure that doesn’t happen.

The Heating Chamber

You can find this chamber only on models that can produce both cool and warm mist.


Basically, when you choose the warm mist, the humidifier stops using the transducer and switches to the heating chamber that boils the water.


The steam produced during the boiling is pumped out into the air with a fan.


This is a much safer way because it kills 99% of bacteria found in the water.

What else is important to know about Ultrasonic Humidifiers?

energy efficiency

This type of a humidifier is quite an energy saver, but only if we are talking about cool mist models.


It consumes less electrical energy and will not hurt your bill as much as one might think.


Also, when it comes to living in areas where the air humidity becomes dry during the summer months, a cool mist Ultrasonic humidifier will allow you to turn down your AC system as it cools down the air temperature in the room for a few degrees.


On the other hand, if you are using the Ultrasonic humidifier that can generate warm mist, you might feel it a little bit on your electricity bill.


But, it heats up the air, meaning that you can crank down the heating system during the winter. And, actually, come out with a lower bill at the end.


When it comes to Ultrasonic humidifiers, the truth is that they need regular tank cleaning. But, so do all other types.


But, considering that it doesn’t use a filter, it is less demanding than the evaporative humidifier.


And, just as with the evaporative, the ultrasonic humidifier also needs proper cleaning and drying after use and before storage. This prevents the development of mold and bacteria in the water tank.


One more aspect that might require maintenance is the demineralization cartridge (if your model comes with one, that is).


You will have to replace it once in two or three months, depending on the hardness of the water you use.


But, if you use distilled water, one cartridge can last up to a year!


This is the strongest advantage of the Ultrasonic humidifiers over all other types.


I mean, not that other types are that noisy, but the Ultrasonic humidifier is practically noiseless. Maybe a few blurbs after refilling while the water enters the transducer section, but that's it.


All the humidifiers in my home are Ultrasonic. And, when my kids were babies, they didn’t bother them during the night even when working on max mist output settings.

Final Thoughts on the Ultrasonic Humidifiers

If you are in the market for a humidifier that is easy to use, produces healthy humid air, is quiet, and isn’t high maintenance, the Ultrasonic humidifiers might be just what you are looking for.


Also, they don’t “eat” much electrical energy, meaning they won’t hurt your budget even if you use them regularly.


I use humidifiers in our home pretty much every day (the air is mostly dry throughout the entire year here). And, we haven’t noticed that our electricity bills jumping.

Wrapping It Up 

Okay, I have given you pretty much everything I know when it comes to how humidifiers work. And, now that you have a better insight, it will be much easier to choose the type for your home.


Just take into consideration all the factors, such as effectiveness, size, cool or warm mist, additional costs after the purchase. And, see which type best suits your needs.