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Does a Humidifier Make a Room Hot?

Dry air can be increasingly uncomfortable over long periods of time, which is why humidifiers are essential items for homes in dry regions. However, humidifiers work by increasing moisture in the air, thereby causing humidity. Since humidity is directly correlated to heat, do these products actually heat up a room?

A humidifier makes a room hot. Humidity makes a person feel warmer based on moisture content, which causes the human body to evaporate less water, causing less cooling. Furthermore, the extent to which humidifiers increase room warmth depends on the type of humidifier: warm mist or cool mist. 

The remainder of this article will explore how humidifiers can make a room hot, and the reasons why humidity produced by them feels warm, even though the ambient room temperature has not increased. Additionally, the type of humidifier may also be causing the warmth as opposed to the humidity output generated by the humidifier.

Pro-tip: Cool mist humidifiers are really effective at preventing dryness that causes irritation in your throat, lips, and skin. If you want to get rid of your dry mouth and reap the many health benefits of a cool mist humidifier, check out the best cool mist humidifiers on today.

How does a humidifier create warmth in a room?

When humidity is released into a dry room, the moisture content will make the air feel heavier due to an increase in volume. The basics as to why this occurs have to do with the process of thermal expansion, which occurs when water vapor released from a humidifier retains the ambient heat already present within a room. Also, warm mist humidifiers are designed specifically to release warm vapor. Let’s explore the variations below.

Since there are obvious differences in how warm mist and cool mist humidifiers release water vapor, exploring how these two types of humidifiers work will provide a quick answer as to why a humidifier makes a room feel warm.

Warm Mist Humidifiers

First and foremost, if you are using a warm mist humidifier, this product is definitely making your room feel warmer. Warm Mist models work by boiling water through a heating element that then releases the warm vapor into a room. Since electrical appliances are motorized, this further adds to the emission of heat into a room.

Since the circulation of warm mist into a room is meant to make the room feel warmer, this is an obvious reason as to why this type of humidifier makes a room feel warmer. But, a cool mist humidifier can also make a room feel warm based solely on the generation of humidity.

Cool Mist Humidifiers

You are probably thinking that this type of humidifier should help to make a room feel cooler, but this is not how moisture vs. ambient room temperature works. Cool mist humidifiers work by moving water across a wick that draws air from the water, which is then pushed out by a fan into a mist that is cooled slightly by the fan.

So, how can this possibly create warmth?

Humidity in and of itself causes the retention of moisture within the human body. Rather the mist being emitted by a humidifier is cool or warm, the increase in moisture within a room is preventing the human body from sweating, which is why it feels warmer even if the room temperature has not changed.

So, even though a cool mist humidifier is releasing cooler water vapor into a room, the human body reacts to increased moisture by retaining internal moisture, therefore causing a warm sensation in response to the humidification. This leads to the most puzzling, yet fundamentally certain aspect about humidifiers: ambient room temperature vs. increased moisture content.

Room temperature vs. Water vapor: Does this factor into room warmth?

Heat is normally generated when an increase of mass and volume invade a small space like a room. In terms of water vapor, this is represented by an increase of volume applied to the dry air already present in a room. This process is known as convection, which is essentially the rise in heat due to an increase in mass, which is basically what is occurring when a humidifier releases vapor into the air.

This is further amplified if the room temperature was already warm or if the air was dry to begin with, which leads to a process known as friction viscosity, which occurs when a liquid (water vapor) consistently collides with a gas (air). Since the air is thin and dry, the immersion of a heavy vaporized liquid causes an increase in friction, which in turn, creates heat. However, if a room is already warm, a humidifier will certainly increase the warmth.

As temperatures begin to rise within a small space, water vapor will also increase its capacity to expand as well. This is known as relative humidity, which is the process where water vapor responds to the ambient temperature already present within the air. The old saying that heat expands and rises is basically what occurs when you introduce water vapor into a warm room. With this established, there are other factors that can cause room warmth from a humidifier.

Does the motor from a humidifier increase room warmth?

There is actually another commonly overlooked aspect as to why a humidifier is likely making a room feel warmer it’s an electrical appliance. All electrical appliances generate heat simply by running. Although this only represents a small fraction as to why humidifiers make a room feel warmer, this is a component that adds to that.

Specifically, in the case of warm mist humidifiers, this aspect is a bit more pronounced as opposed to cool mist humidifiers. Warm mist models are operated by a heating mechanism, which not only uses more electricity through its currents but also generates heat to warm the water vapor. The combination of electrical currents and heater are substantial.

With cool mist humidifiers, the motor only generates a small amount of heat as the electrical currents run through the motor, but when you combine the already warm conditions that any type of humidifier creates in a room with the slight amount of warmth from a motor, this is enough to create warmth even if the mist is cool.

As previously mentioned, this aspect is not going to be incredibly noticeable, especially since we are all surrounded by electronic devices in our home, but since a motor within a humidifier does generate heat, this aspect must be included in the overall warmth that a humidifier generates with a room.

The overall consensus.

Ambient room temperature, differences between cool mist and warm mist humidifiers, the relationship between heat and humidity, and the heat generated from electrical appliances all collide to make a room warmer no matter the type of humidifier that you are running in a room.

A key aspect of the warmth generated by these appliances has to do with the temperature of the air within the room before you turn the unit on. Humidity and heat complement one another, and water vapor will always increase humidity when meeting air.


Humidifiers, either warm mist or cool mist, can make a room feel warmer even if the temperature in the room is cooler. All of these aspects are scientific in practicality: thermal expansion, the relationship between heat and humidity, convection, and friction viscosity. The temperature with your room is also affected by the introduction of water vapor. When air and water meet, volume and mass increase, which then produces heat.

Plus, simply running an electrical appliance adds to the feeling of warmth within a space. Although humidifiers do make a room feel warmer, the benefit of increased moisture is worth the warmth.


  • Steve Rajeckas

    Steve Rajeckas is an HVAC hobbyist with an avid interest in learning innovative ways to keep rooms, buildings, and everything else at the optimal temperature. When he's not working on new posts for Temperature Master, he can be found reading books or exploring the outdoors.

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