Last month, we were contacted by an angry customer. The evaporative cooler she’d bought for her office wasn’t doing anything. Her office was 77°F when she switched it on and it was still 77°F two hours later. The only difference was the humidity. It had risen from 29 to 50 percent.
The problem wasn’t her cooler, however, it was her office. All the doors and windows were sealed, and evaporative coolers can’t operate without good home ventilation. Once she opened a window and let in some fresh air, the cooling mechanism finally started to operate temperature began to drop.
Why Evaporative Coolers Need Air Circulation
Evaporative cooling is governed by three factors. The first is temperature, which determines the amount of energy molecules have. The more energy, the easier it is for water molecules to break the bonds holding them together and become water vapor. The second it humidity. Evaporation happens quickly when humidity is low and slowly when humidity is high. The more water vapor is in the air already, the less vapor the air can absorb. The final factor is air flow. When water evaporates, the vapor hangs close to the water’s surface and gradually dissipates. By keeping the air moving, air flow reduces humidity levels along the point of evaporation and increases the rate of evaporation.
In a closed room, however, air flow is ineffective. Evaporation won’t occur if the air being pulled in is just as humid as the air being blown away. The only solution is to replace the humid air with fresh air by opening the doors and windows ventilating the room.
How to Ventilate Your Home
Home ventilation relies on negative air pressure, when the air density inside your home is less than the density outside. If you’ve ever felt a cross breeze in your home, it was created through negative air pressure. Often, simply opening two doors or windows directly across from one another is enough to create negative air pressure. As air escapes through one window, it naturally pulls air in through the other, especially if there is already a light breeze outside.
You can increase air flow by placing your evaporative cooler in front of an open window or door and pointing it at another window opposite. It not only provides the cooler a steady stream of fresh air, but the cool air it blows out helps push the humid air out of your and draw more air in.
The Chimney Effect
If you live in a two-story home, the best way to ventilate is with the chimney effect. Because hot air rises, heat is going to naturally accumulate in the upper levels of your home. If you open the windows upstairs and place your evaporative cooler in front of an opening downstairs, you’ll force the hot air out through the upper windows and pull cool air up from downstairs. Another way home ventilation and evaporative cooling work together.
Want to learn more about improving home ventilation? Check out the article on evaporative coolers and home ventilation in our product knowledge base or ask a question in the comments.