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Does a Window Have to Be Open When Running a Swamp Cooler?

Roz Calvert

Evaporative air coolers, sometimes called swamp coolers, can lower room temperatures as much as 30 degrees. Forcing fresh air over damp fabric to cool a space is one of the oldest methods of air conditioning. It is easy and effective in dry climates. Even though the principle is simple, you may have questions about how evaporative cooling systems should be run.


Open windows let out hot air when you're using a swamp cooler.

Air conditioning cools and recirculates air in a room or in an entire building. It is essential to keep the windows closed so the cooled air does not escape. However, swamp coolers work differently. They pull fresh air into a room, and as it passes over damp pads, it cools the room. As the cool air fills the room, the hotter air is forced out. With really efficient evaporative cooling, a total air change in the space can take place every two minutes.


Evaporative air cooling systems can cool an entire dwelling or a single room. The room units are often placed in windows, not unlike window air conditioning units. In larger systems, duct work and fans together move air throughout the space to allow cool air to enter each room. A simple system uses one duct and fan setup to let in air and blow it into the house.


The purpose of opening a window is to let the warm air escape as the cooler air is circulated by the swamp cooler's fan. Open the door and a window inside any room you wish to cool so the air can move through. To get a balance of cool air throughout the space, leave both a door and window open in the room to allow air to circulate.


How much you open a window can determine the swamp cooler’s efficacy. Open the window just enough so the door closes very slowly. This means the pressure is balanced, and the hot air is moved through the window as exhaust. If the door slams, the window is not open wide enough. However, don’t open the window too far. If the door does not move, the window is too widely open. When the door closes completely, open it and start the process over.