Cooler Study In 1992, the city of Phoenix asked the University of Arizona’s Office of Arid Lands Studies to design a research study with the goal of accurately quantifying the water-use and operating characteristics of evaporative coolers currently in use in Phoenix. The university and the city conducted the study, with funding from the Arizona Department of Water Resources. The study represents the first statistically sound and repeatable attempt to quantify evaporative cooler water use in a broad sample of Phoenix residences. The research was conducted between the spring of 1993 and the fall of 1994. This was an initial step in establishing programs to both improve understanding of actual water use by these appliances, and to provide a starting point for improvements to the water consumption efficiency of evaporative coolers. The field study involved metering the water used by a structured sample of home coolers to better estimate citywide evaporative cooler water demand. The intent was to secure a statistically valid sample of water use from existing systems, producing a valid “slice of the real world” with a high level of reliability to the city at large. The research plan was designed to monitor the performance of 46 evaporative coolers in Phoenix in the summer of 1993. Twenty of those coolers also were monitored during the summer of 1994, as a check against variations in summer temperatures and rainfall. Previous surveys estimated that coolers with bleed-off systems represented about half the coolers in use, and that homes with evaporative cooling as the only cooling source represented about 13 percent of all homes. To have sufficient data points for each category, it was determined that half the test houses would be ones with bleed-off systems and half the homes would have dual cooling systems. Results Average daily water use by evaporative coolers for the two summers of the study was 66 gallons per day. This varied significantly, however, depending on whether the cooler was equipped to bleed off water or whether it evaporated all the water that came into the pan. Coolers with no system to bleed off water used an average of 3.5 gallons per hour of run time, while coolers that reduced the salt buildup by constantly dumping and replacing part of the water while the pump ran used an average of 10.5 gallons per hour of run time. The percentage of household water use that was used by the cooler also varied significantly, from 2.5 percent to 66.8 percent of total summer use. The average for houses with no air conditioning option was 25.8 percent, and for all homes the average use was 15.8 percent. On average, the coolers ran 2,100 hours during the summer. Average consumption of water for cooling, as well as total hours of cooler run time were both heavily influenced by the number of homes that could switch to air conditioning. Water in the desert southwest is high in dissolved salts; mostly calcium. It is harmless in the drinking water supply, and expensive to remove. It can cause problems for coolers if it becomes too concentrated. The result of high total dissolved solids (TDS) is a build-up of calcium salt on cooler pads, pumps, pans and sides. It is corrosive to metal and will shorten the life of a cooler. Quick Facts • Operating expense is typically 75% less. • Unit cost is nearly 50% less. • Installation cost is 50% – 80% less. • Units use 120 volt electricity, so no special wiring has to be installed or utilized. • Master Cool also offers a limited lifetime warranty on all Single Inlet Evaporative Cooler Wet Sections. • Evaporative Coolers add fresh air to the home, unlike traditional air conditioning that repeatedly recirculates the same air. A complete change of air occurs within the home every two or three minutes. How can it save me money?

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