mieletag
Well-known member
Actually, the evaporative cooling does work, but the relative humidity must be low enough for the process to work correctly. When the hot dry air enters through the water soaked pads, a little bit of the water is evaporated, taking away heat with it. That is why there is generally a constant makeup water supply available, usually a float, to replenish the evaporated water. But, I have been hearing for several years now that the dry Southwest is getting more humid than it was years ago because of lawns and swimming pools and people just using more water in general, and swamp coolers are not quite as effective as they once were. As the latent load increases (humidity), the sensible load (dry bulb temperature) is not as easily controlled.