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An alternative to an air conditioner, a swamp cooler uses evaporation, rather than chemical coolants, to lower the temperature of air. People who live in dry, hot climates have long heralded swamp coolers as being effective at cooling and humidifying homes. In ideal conditions, a swamp cooler can reduce the air temperature by about 30 degrees Fahrenheit (17 degrees Celsius).
How it Works
A swamp cooler uses the basic principle of evaporation along with simple technology and electrical power to create cold airflow. First, one motor pumps water into pads of a fibrous, absorbent substance similar to hay, called cellulose. Then another motor powers a fan that pushes air through the pad, which is always full with fresh water.
When the entering air is very hot and very dry, some of the water evaporates into it. Evaporation needs molecular energy, otherwise known as heat, which ends up reducing the temperature of the air and adding humidity. Finally, the cooler air is pushed through a duct into a central location in the building that is being cooled, such as a hallway or main room.
Not only does a swamp cooler lower the temperature of the air, it also makes the atmosphere more pleasant. The chilled air is slightly damper and always freshly recirculated. This gives the swamp cooler many advantages over an air conditioner.
Air conditioners recirculate old air and actually reduce the humidity, which can prove uncomfortable and unhealthy in a dry climate, such as the kind found in a desert region. A moderate degree of humidity in the air keeps a person's mucous membranes moist, thereby increasing those membranes' effectiveness at improving the body's immunity. Also, swamp coolers use significantly less energy, so they conserve electricity when compared with the energy used by air conditioners. Swamp coolers do use more water, though.
Less Useful in Some Climates
A swamp cooler works best when the temperature is more than 80 degrees Fahrenheit (27 degrees Celsius) and the humidity is less than 30 percent. This makes swamp coolers ill-suited for hot and wet climates. The air is already so heavy with humidity in those climates that very little water will evaporate, and the exterior air will be almost the same temperature as the air that already passed through the swamp cooler.