Issues

Since 1982, Thanksgiving Tower has been a well-known office building in the Dallas skyline. In 2013, the 50-story tower was scheduled for a major $16 million mechanical renovation to include new HVAC, plumbing, electrical, and life-safety systems. Late 2013, the replacement process began to the building's original chillers, cooling towers, air handling units (AHUs) and building automation system (BAS), among other equipment.

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The building operates on a chilled water system with thermal storage. "Thanksgiving Tower is one of the first buildings in the country to feature a variable air volume (VAV) system," says Jim Barrilleaux, senior mechanical engineer with TDIndustries of Dallas, which provided mechanical contracting. Barrilleaux is very familiar with the building's HVAC system after having worked on the HVAC design when the building was constructed in the early 1980s, and again in the current renovation.

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Custom air handlers by Daikin Applied were an easy choice given the new units would replace the original, former McQuay air handlers. "As the property manager, our considerations were keeping tenant disruptions to a minimal and fast turnaround," says Rick Matvey, operations manager with Lincoln Property Company (LPC).

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Solution

The 96 AHUs were designed to suit the building's existing space requirements. "We used the versatility of Daikin Applied's manufacturing process to adjust the height and width of the units to accommodate our dimensions," Barrilleaux says. "This allowed us to perform the installations efficiently and minimize the changes to the existing duct locations." The modular construction of the air handlers allowed for TDI's field crew to more easily connect transition pieces to the existing duct locations.

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"The project team was very appreciative of Daikin's willingness and ability to ship the fan assembles separate from the rest of the AHUs," says Grant Yaney, Daikin Applied representative with HTS Engineering in Dallas. The delivery accommodation ensured the AHUs would fit on the elevators and that the delicate but heavy fan assemblies wouldn't be damaged when tilted to fit elevators and hallways.

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After a successful test run with the first AHU installed in January 2014, installations were staged over a several-month period from April through December 2014. Two units were installed per floor, each in a mechanical room at opposite ends of the floor. "We had anywhere from eight to 16 units delivered at a time which were stored on the building's empty floors. We averaged two installations during the week and another four on weekends to minimize tenant disruptions," says Chuck Stroud, superintendent with TDIndustries, noting that the patented splice collar design of the air handlers saved time and installation costs versus those that require gaskets between each section.

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In addition, about 20 percent of the AHUs required significant disassembly at the job site to accommodate other equipment in certain mechanical rooms. Stroud adds: "We were able to completely take apart these units and reassemble them without regard to their original unit, so we appreciate the manufacturing tolerances."