How important is CFM/CMH when Choosing an Evaporative Air Cooler

Who doesn’t like the feeling of a cool ocean breeze on the skin? With an evaporative air cooler (EAC), you can experience the same feeling every day in your own home. But before you go out and buy the first EAC that catches your eye, you should learn what CFM/CMH is and how it affects the performance of EACs.

How Do Evaporative Air Coolers Work?

EACs are surprisingly simple machines considering how effective they are. They rely on the natural power of evaporation by pulling in hot, dry air through a moistened pad. As the pad absorbs the heat from the air, the moisture in the pad evaporates, cooling the air by as much as 20 degrees.

Because most EACs only contain a simple water pump and a ventilator, they are cheap to operate, easy to maintain, and extremely reliable. Instead of recirculating cooled air inside the building, EACs continuously blow fresh air through your home from outside and push stale air out through an opened window or door.

What Is CFM/CMH?

To choose the right size evaporative cooler for your home, it’s important to know how many cubic feet of air per minute (CFM) or cubic meters per hour (CMH) it can pump. It’s also useful to know the speed of air, which is expressed either in feet per second (FPS) or meters per second (MPS).

A research paper presented during the annual International Joint Conference on Materials Science and Engineering states that “the heat absorption rate is increased by higher velocity.” The researchers found the optimal speed of air to be exactly 3.4 MPS. This explains why some manufacturers of EACs are able to claim very high CFM/CMH values even though the actual performance of their products is sub-par because of insufficient airspeed.

How to Choose the Right Size EAC?

Choosing the right size EAC for your home is relatively simple. The only thing you need to do is determine how many CFM/CMH you need.

  1. Determine the average ceiling height in your home.
  2. Multiply the square footage by the average ceiling height in your home in feet.
  3. Divide the number you get by two to arrive at two air changes per minute.

For example: 2,000 sq. ft. x 8 ft. = 16,000 / 2 = 8,000 CFM

However, it’s important not to forget that CFM/CMH determines only cooling capacity, but there are many other parameters you should take into consideration when choosing an EAC, including your local humidity level and extra features. EACs are packed with a variety of features : carbon dust filter that can trap allergens and smells, remote controls, energy efficiency, drainage options and more.

In the next section, we recommend four EACs, each offering a different cooling capacity and set of features. We recommend you determine how many CFM/CMH you need and then pick an EAC that meet your requirements and offers the most compelling features at the most attractive price.

Honeywell CS071AE

The CS071AE is the best-selling EAC on Amazon. It’s extremely quiet and can pump up to 176 CFM while consuming only 32 watts of electricity at the highest speed setting, which is less than what most traditional lightbulbs consume. If you’re having trouble falling asleep when its hot at night during the summer, the lowest speed setting will provide you with long hours of quiet comfort at night.

Hessaire MC37M

The Hessaire MC37M is a compact EAC with a cooling capacity of a much larger unit. Hessaire has achieved the amazing performance using the combination of expanding air-intake areas with special high-density pads. The Hessaire MC37M can be connected directly to a water source, making it perfect for demanding outside use.


Luma Comfort EC220W

Thanks to its mind-blowing cooling capacity of 1,540 CFM, the Luma Comfort EC220W High Power 1650 CFM Evaporative Cooler is able to cover up to 650 sq. ft. and blow cool air to all directions with its oscillating fan. This EAC has three cooling speeds, allowing you to pick the optimal setting for every occasion.



Honeywell CO30XE

Perfect for the southwest and Midwest regions of the US, the Honeywell CO30XE is a weather-resistant EAC suitable even for outdoor use. It’s rated at 525 CFM, has a 7.9-gallon tank for easily accessible water filling and maintenance, comes with a top-loading ice compartment for colder air in your hotter spaces, and can be operated using a convenient remote control.


1 comment

I want to know more about the drainage will I have to dump water before I buy one

Joann West June 05, 2019

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