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Are Air Purifiers Also Fans? Clearing Up A Common Question

Are you somewhat familiar with how air purifiers work? If you’ve been around one before, you probably already know that most move air. If you aren’t familiar with them at all, that’s ok, too! As they obviously work by moving air somehow, it’s easy to see why you might wonder if air purifiers are also fans.

I’d love to help you learn more by answering that basic question. Additionally, I’ll go into much more detail about how air purifiers work and why they’re helpful.

You’ll also find out a bit more about a few that actually do act like fans as well.

The basic question: are air purifiers also fans?

The general rule is “No.” Air purifiers aren’t fans alone. That is, while they do move and circulate air, most cannot do so with the high speed & larger airflow of a basic electric fan.

More importantly, they’re designed for cleaning the air you breathe which in turn makes a large impact on the airflow volume they can provide.

Standard electrical fans don’t have the same restrictions caused by doing other work like an air purifier does. Because of that, ordinary fans can blow air much faster in order to cool you and the room you’re in.

Read on and I’ll explain why they’re not fans . First, let’s talk about what a fan is and then what an air purifier is. I’ll then compare the two and explain specifically how they’re different.

What is a fan and how does it move air?

Diagram of axial and centrifugal electric fans

Electrical fans come in different styles and serve different purposes. Both use an electric motor to rotate blades which cut through the air and cause it to move from one side to the other, creating airflow. Both centrifugal and axial style fans are used in air purifiers. You may have seen axial fans used in your desktop computer case, for example. The curved blades on a fan cause the motion of air that is so important.

A fan is a device with fixed blades (usually curved) that force nearby air to move from the rear to the front of it in a blowing motion. It’s a common misconception that a fan cools air because it actually doesn’t. Instead, it moves air to create the opportunity for cooling by the evaporation of sweat and convection in an environment.

In other words, fans move a liquid or gas (air) rapidly to allow cooling to occur on you or an object.

Normally they’re powered by an electrical motor which uses many windings of copper wire to produce movement and turn the blades. This is done by allowing electrical current to pass through the windings which then creates magnetic fields.

These fields in turn push away from other magnetic fields and the rotor, the rotating center section, turns. The fan blades, attached to the rotor, then cut through the surrounding air and the air is forced to move.

Typically the fastest fans have the greatest flow of air.

Evaporation

Sweating is how your body self-regulates its temperature. As your sweat evaporates, your body cools off because it requires heat to convert water to vapor. In still air, however, it isn’t so easy for sweat to evaporate. The air circulated by a fan helps the sweat on your skin to evaporate faster.

That’s why you feel cooler when there’s a fan blowing around you or on you.

Convection

Aside from helping regulate heat by helping your sweat to evaporate, fans also have a role to play in a process called convection. For our purposes, we’ll consider this process as heat moving away from one place to a cooler place. When you feel hot and the surrounding air is cooler, your body cools down by transferring heat to the air.

Air that has been heated becomes less dense and rises. When you have a fan in the room, it helps to carry this warm air away. Cooler and denser air will settle down and the cycle continues, making you feel cooler.

Fans are generally designed to blow air as I mentioned above, although there are some fans that are designed to suck or pull air. Some examples exhaust fans, vacuum cleaners, and range hoods (like you’ve seen in restaurants or perhaps in a home kitchen).

We’ll leave fans here for the moment and take a look at air purifiers.

What is an air purifier? How does an air purifier work?

Diagram showing how a GermGuardian AC4900CA air purifier worksAir purifiers work by moving air through filters and trapping airborne elements that cause pollution, allergies, asthma, sickness, and much more. Additionally, with an active carbon filter (a separate type of filter) they can trap odors and airborne chemicals. Some products like this GermGuardian AC4900CA also include a germ-killing feature using ultraviolet (UV) light.

An air purifier is an electrical device that eliminates airborne pollutants in a room. Most air purifiers contain an electric fan which pulls air to the intake part of the device. Air is then forced through a series of replaceable filters where pollutants are trapped. After the air is cleaned it is released back into the room.

As the process continues the air purifier will continuously cycle and filter bad elements and odors in a room. The end result is fresh, clean, healthy air being left behind.

Air purifier filter types

Image of a GermGuardian AC4100 showing HEPA and activated carbon filtersA small air purifier (GermGuardian AC4100) showing the dense HEPA filter (white) and the activated carbon pre-filter (black). These work together to remove foreign particulates and substances like odors from the air. Neither can work alone to perform both functions.

High-Efficiency Particulate Air (HEPA) filters are made of very thin entangled glass threads that are formed into a flat sheet, which is pleated like an accordion. Think of it as being an extremely dense material with gaps far too small to see with the human eye.

This material works to filter & trap 99.97% of airborne particulates and allergens as small as 0.3 microns (that’s 1/1,000,000 of a meter in size).

Activated carbon filters are often used in conjunction with HEPA filters because of their porous nature which makes them highly effective at absorbing volatile organic chemicals, odors, and some gases in the air. They may or may not be a part of an air purifier that you buy.

It depends on the design of the product.

Pre-filters are usually made of washable foam or nylon materials that trap larger particles. These are often integrated with HEPA and carbon filters so as not to overwork the more expensive filters. They’re typically a less dense and thinner filter serving mainly just to trap larger elements in the air like dust, insects, hair, and so on.

They’re generally used as a 1st stage in the filtering process if provided.

Aside from different filters used, there are also different types of air purifiers. Some use ultraviolet light (UV) rays to destroy mold, mildew, viruses, and other germs in the air as they pass by. There are also ozone-generators and negative-ion air purifiers that remove microbes and gases but produce ozone molecules as a functional by-product. Ozone-producing air purifiers are not approved by the Environmental Protection Agency (EPA).

So, are air purifiers also fans in a way?

AC4825 rear motor and fan illustration
Air purifiers contain electric fans which are used to draw in dirty air and blow out clean, filtered air. The pink arrows in the image point to the centrifugal fans used in this GermGuardian AC4825 purifier. In the center you can see the silver electric motor used to drive them both.

As I mentioned at the beginning of my post, it’s important to understand the difference between a regular fan and an air purifier.

1. Unlike fans, the majority of air purifiers have filters which greatly slow the flow of air through them.

That’s why they’re not capable of moving enough air to cool you or your room. The rate depends upon the purifier’s fan speed in use and efficiency.

These two products are not the same because they’re designed and made for different purposes.

The way they operate is different, too. They’re similar in the sense that both cause the air in your room to circulate. Fans circulate air in a room as a side effect of how they work – often they’re used to blow air directly.

Air purifiers, on the other hand, filter airborne particulates and circulate the air as they go through the dynamics of air purifying. Air circulation, rather than blowing air directly in any particular direction, is critical to how they function.

2. Most purifiers aren’t designed with fans that can move enough air to cool a room.

Purifiers aren’t expected to clean all of the air in a room rapidly. It can take anywhere from a several hours to a few days depending on the product and the room size. Air purification is a process that takes time.

If you required something that was much faster, it would be much larger in size and more expensive. That isn’t practical and very few people would be willing to pay for that.

There are also some types that don’t have fans. These products don’t add to the normal circulation of air in a room, and thus don’t have the added function of a fan. Ionizers and some ozone generators are good examples of this type.

Examples of air purifiers that are fans

Image of air purifiers that are fans
There are a few exceptions to the rule. A few products on the market actually do act as fans. The Honeywell AirGenius product family (left) and Dyson air purifiers like the Pure Cool purifying fan (right) create a very high air flow in a room much like a fan.

While what you’ve read is true for most, there are a few exceptions to the rule. Some products like the Dyson Pure Cool purifying fan are designed specifically to move large amounts and offer cooling.

Others like the Honeywell Air Genius 5 have a different type of filter design which allows a high rate of air to blow just as a fan (and even oscillates to blow air like a fan).

In conclusion

Most air purifiers are not, in the most strict sense, fans. They can’t move large amounts of air rapidly like fans and cannot cool you or your home. There are a few models, however, that are exceptions to this.

Unlike a fan, the typical air purifier:

  • Can’t produce high-speed air flow – the filters inside greatly reduce it
  • Won’t cool you or the room, as the air flow doesn’t extend very far past the purifier
  • Needs a lot of time to circulate the air in a room

As most air purifiers operate, they do circulate the air in a room, which is the function of a fan. So in that respect, they do work as fans. But we draw the line there because an air purifier is more than just a fan.

If the ability to cool a room is important to you, plan on purchasing a fan separately. You can, in most cases, use a fan in the same room with an air purifier without any problems!

Hopefully I’ve cleared up the question for you and helped you better understand the differences.

Wondering if you can use a purifier with the windows open? Here’s a helpful post I wrote to answer the question about air purifiers and open windows.

2 Comments
  1. Thank You very much! Your advice was very helpful in many ways. Also, I appreciate that you were able to give me not only the answer to my question I had been searching for but, some good comparisons and some things I never new. Plus it was very short and direct. Not long drawn out that I had to search threw your post for my question to get to an answer. Thank You. I will defiantly be needing your advice in the future I’m sure, I always have questions!

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