Evaporative Coolers ✳︎ How they Work ✳︎ Venting Tips

Arid climates have a love affair with Evaporative Cooling. Why? Because evaporative coolers are efficient and cost-effective to run compared to air conditioners. They work well in the Sonoran and Mojave deserts and popular in the southwest states of Arizona, California, and Nevada. Most months, they work like a dream dropping temperatures thirty degrees or more when the humidity level low. However, as temperatures increase and monsoon season sets in pushing humidity levels up we suddenly find ourselves shopping every aisle at the store or going to the movies to stay ... COOL!

What’s the difference between air-conditioned and evaporative cooling systems?

You may be more familiar with an A/C system, which "conditions" the air, by processing air from within the house, cooling it and then filtering it back into the house. Air-conditioned systems are "closed loop" and require windows to be shut.

The process of an evaporative cooler (aka swamp cooler) draws air into the home past wet media pads and distributes through a ducting system, this moisturized air reacts with the already dry conditions causing evaporation. The pleasant and welcomed effect of evaporation is the reduction of temperature. The replaced cool air along with proper venting pushes hot air out of the house. This process requires some sort of venting and is usually accomplished by opening windows or in some homes the placement of up ducts in rooms.

"Pressure, venting it seems so complicated"

It may seem complicated but keep in mind there needs to be enough venting so that the cooler is able to move air into and out of the dwelling. If there is not enough venting, the house fills with air causing a backpressure on the cooler, which it cannot overcome, and results in less airflow. Conversely, opening doors and windows too much actually may result in defeating the cooler, by allowing hot air into the house, which the cooler was supposed to be pushing out. A simple rule of thumb is to have the house air pressure remain a bit "over-pressured" to prevent hot air from blowing into the house.

How to create proper venting

You can adjust which part of the house receives more cool air by adjusting the venting in that area. Remember that venting equals airflow. Many folks will close windows in bedrooms during the day and open windows in the main living area, to cause the living area to remain cooler. At night, they will open the bedroom windows and close the living area windows, drawing the cooler air through the bedrooms. It is a balancing act, which takes some trial and error to see what works for you.

Three easy venting tests everyone should know

  1. Open the windows the way you think they should be, perhaps four to five inches. Go to the front door and pull it open. There should be a slight drag as you open it. If you have the door open about three inches and release the handle the door should pull itself shut because of the air pressure. It shouldn’t slam shut, but it should close on its own. If it slams, you need more venting. If it doesn’t close, you have too much.
  2. Tear a quarter size piece of paper and place it on the screen of an open window. With proper venting, the air pushes out holding the test paper against the screen. If the air blows the paper back into the house, there is too much venting and you need to close some windows.
  3. Take a peek at the trees, bushes, and flags outside. If the wind is blowing, don’t open windows on that side of the home unless protected by a windbreak. Even the slightest breeze may result in blowing hot air inside. When you feel a warm breeze sneaking in, it's time to switch up what you have open.

Maintenance and staying comfortable

Proper maintenance is important. Each spring RENT29 performs a system check-up to make certain all components are working properly including cleaning or replacement of media pads, testing the float, pump, and water distribution. Between guests and throughout the summer we may schedule additional check-ups. Unfortunately, even the best-maintained systems may have components fail in which we will address as quickly as possible.

Keep in mind that summer temperatures can range greatly from the most pleasant of days to heat waves. When the combination of triple digit temperatures along with higher humidity level collide the cooling effect will be reduced. We understand that comfort is a little compromised but follow the tricks above along with the use of fans and you too can make it through any heat snaps.

Air Temperature to Humidity Level shared by Rent29.com

The chart depicts an approximation of temperature changes delivered by a evaporative cooling related to outside temperatures and humidity levels.  


Design and function of an Evaporative Cooler

Rustygoose Evaporative cooler diagram shared by Rent29.com