What Is an Evaporative Cooler and How Does It Work

Learn how evaporative coolers work and how they differ from air conditioners

If you live in a hot and dry region, installing an evaporative cooler in your home is a great alternative to an air conditioner. These units are an energy-efficient way to cool your home while infusing the air with moisture. Most are easy to self-install and operate quietly so you hardly notice they’re running. 


What is an Evaporative Cooler

Evaporative Cooler Definition

The terms “swamp cooler” and “evaporative cooler” are often used interchangeably. Also referred to as "desert" or "wet air" coolers, these coolers are most popular in drier regions. Evaporative coolers are designed to circulate evaporated water through the air. This cools and adds moisture to the room or surrounding area and is a cost-efficient climate control method.

Evaporative coolers use very little energy, making them an environmentally friendly option for many homes. Installing one is a great way to keep indoor air fresh and cool, especially with the windows open. However, if they are not properly cleaned and maintained, a marshy or swamp-like odor can begin to develop. Changing the pads at least twice a season helps avoid this issue.

How Does an Evaporative Cooler Work

How Does and Evaporative Cooler Work

An evaporative cooler works by reducing the nearby air temperature using evaporated water. The unit includes a fan, water tank and internal motor, which passes dry air through a wet, internal filter pad. It is quickly cooled and circulated throughout the room. Opening nearby windows helps renew the air every few minutes and keeps the breeze fresh.

Since evaporative coolers require dry, hot air for optimal function, they are best suited for warm and arid climates. In the US, they are most popular in southwestern states like Arizona and New Mexico. During the winter months, the cooler should be fully drained, disconnected and covered in an enclosed storage area.

Swamp Cooler vs. Air Conditioner

Swamp Cooler vs. Air Conditioner

Swamp coolers differ from air conditioners in various ways. Instead of recirculating stagnant air, swamp coolers pull fresh air from open windows nearby. They generally require less maintenance and are also less expensive to install.

Costs to operate an air conditioner are higher than operating a swamp cooler, but air conditioners work well in any climate. Swamp coolers require a hot and dry climate to run efficiently, and unlike air conditioners, the performance quality is not compromised by open windows and doors.

Both swamp coolers and air conditioners are available as a large, central system or as a window unit, but it’s important to note that swamp coolers add moisture, whereas air conditioners remove it. For this reason, it’s not fitting to use both in the same home. There are many pros and cons to both cooling systems, so assess your situation and choose the one that best fits your needs.

Evaporative Cooler Types

Evaporative Cooler Types

There are many types of evaporative/swamp coolers available:

Small Swamp Coolers

• Portable by design
• Indoor and outdoor options available, including window evaporative coolers 
• Smaller water tank

Large Swamp Coolers

• Designed for large-scale cooling solutions
• Whole-house swamp coolers are usually placed outside the home (e.g. roof evaporative coolers)
• Professional installation recommended

Portable Evaporative Coolers

• Designed to cool the immediate area
• Smaller than standard window and indoor units
• Easy to carry from room to room

Tip: Read our Evaporative Coolers Buying Guide for help choosing the right one for your home.