Business / Real Estate / Evaporative Coolers (Swamp Cooler): An economical method of cooling a home in a dry climate. An evaporative cooler is a large box-like unit, four sides of which are removable panels with vents that let air flow through. Inside of each panel is a cooler pad, usually made of wood fibers. The unit contains a large fan and a water pump. At the bottom of the unit is a water reservoir. Water is pumped from the reservoir, continually soaking the cooler pads. The fan draws hot outside air through the pads. As the warm air evaporates water from the pads, heat is carried away, cooling the air by up to 20 degrees-F. The water-cooled air is then pumped into the house through an air duct.