United States Naval Base – Hospital Building 449

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Repair & Replace Cooling Tower and Air Handling Unit, Groton/New London, CT

This project involved design to remove and replace an existing 600-ton cooling tower, another existing approximate 100-ton condensing unit and to modify the controls for an air handling unit serving the hospital for the U.S. Navy sub base. The existing tower had corroded before it’s time. Aztech Engineers, Inc. prepared a design analysis and determined that injection steam coupled with the closeness to the sea and the galvanized steel construction were the main contributing factors to the towers early corrosion. The direct steam injection was replaced with a steam to water heat exchanger in an adjacent mechanical room and the galvanized steel tower was replaced with a stainless cooling tower.

During the design analysis we also discovered that the vortex dampers in the existing air handling units were not operating correctly. The vortex dampers were replaced with variable frequency drives, controlling the air handling unit fan based on discharge pressure, allowing the fan speed and power usage reduction during moderate load times, conserving energy. A condensing unit serving an air cooled chiller was also replaced as part of this project requiring detailed equipment capacity matching. Equipment specification could be based on performance only for this project. Manufacturer and model numbers could not be named. Creative specification writing techniques were employed to ensure that replacement equipment matched existing conditions and related existing equipment.

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