School Calls for Chiller Upgrade

Staff -- Consulting-Specifying Engineer, 1/1/2001

The children's center at Washington Elementary School in Sacramento, Calif., is open year-round, and with a number of classrooms lacking windows, there is a constant demand for cooling. High charges for peak usage, coupled with the inefficiency of old chillers, called for a chiller replacement.

The school had been using a pair of air-cooled reciprocating compressor chillers that were 20 years old. The primary unit had a cooling capacity of 60 tons, while the secondary unit's capacity was 40 tons. The challenges were to provide efficient operation at varying loads, control the existing secondary chiller with automatic lead/lag operation and install a new, quiet primary chiller that fit on the existing concrete pad.

With design ambient conditions of 105°F dry bulb/71°F wet bulb, designers undertook a comparison of evaporative- and air-cooled chillers-based on the load profile and the unit delivering 45 tons-and determined that the evaporative-cooled chiller would deliver an operating savings of about 60 percent.

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