Although air coolers and air conditioners were invented to turn hot air into cool, the science behind each method is quite different. What is a swamp cooler? It’s just another name for an evaporative cooler. Water is used to wet absorptive pads around the sides of the cooler. A fan or "squirrel cage" draws outside air through the pads and the air is cooled as the water in the pads evaporates. The major benefit of this type of cooler is that you only need to power a water pump and a fan to draw the air through the pads. They typically use between three and 10 gallons of water per day. That's equivalent to a few toilet flushes or, on the high end, a short shower. Unless the relative humidity is lower than 30% or so, swamp coolers are not very effective. They work well in the southwest, west Texas, and parts of Idaho, Washington, Colorado, Wyoming, and Montana. In those areas the best you can probably do is a 20 degree differential between outside and inside. Also, ...