How Humidity Affects Swamp Coolers

Function

• Swamp coolers use water absorbent pads, pumps and pipes, motors and fans to draw air through the cooler, which evaporates the water, cooling the air. The coolers circulate the cooled air throughout the building and the air exits the structure through vents or open windows. Some people use the coolers during the dry months in the summer and switch to portable or central air conditioners when the humidity levels rise.

Considerations

• When dew points fall below 55 degrees Fahrenheit, the coolers work well. However, when the humidity levels increase, less water evaporates, which increases the temperature of the air coming into the home. The dew point is the temperature at which dew could form. The dew points vary throughout the day based on the humidity. In the morning, humidity levels may be higher. But as the air heats in hot climates, the dew point drops, making the cooler put out drier air, which feels more comfortable.

Benefits

• Places in the U.S. where evaporative coolers work well are primarily in the southwestern states, where summer humidity levels are low. These coolers save considerable electricity because the motors that run the fans and pulleys use far less electricity than air conditioning compressors. The coolers themselves typically cost less than central air conditioners and the maintenance and repair of evaporative coolers are easy and inexpensive.

Warnings

• When humidity levels rise in the summer, the swamp coolers work less effectively. The units also raise the humidity levels of the air inside a home, which can promote the growth of mold and bacteria. The ideal humidity levels for homes lie between 30 and 40 percent, while using a swamp cooler when the humidity is high outdoors can easily raise the water vapor in the home well over 50 percent, which can aggravate allergies. Metal can start to rust or corrode when the humidity levels get too high. Don't operate some electronics in humid buildings.