In the spring of 2011, Vanderbilt University Medical Center sought to update HVAC equipment for a 17,000 sq. ft. research facility within its 800,000 sq. ft. Medical Center North building on its Nashville, TN campus.  The existing air handling unit, originally field-erected inside a roof-mounted penthouse, had begun to fail and was no longer providing adequate air flow throughout the facility.

Mechanical systems engineers at the university were primarily concerned with completing the project as quickly as possible, and ideally over the course of a single weekend, as the facility itself supported important ongoing research.  Disruptions from prolonged HVAC system downtime and/or an extended construction timeline could present notable and costly setbacks, and the mechanical team became responsible for identifying a solution that would ensure neither issue occurred.

To keep within this project timeline while also minimizing (if not altogether eliminating) need for demolition to existing infrastructure, Vanderbilt University’s mechanical team additionally hoped to retrofit a system that could be assembled onsite, with parts that could be lifted via crane through a 6-ft. wide opening in the 65-ft. by 82-ft. rooftop penthouse.  

“There were some very specific parameters around this job, including the desire to keep demolition and reconstruction to a minimum,” says Michael Gable, PE CEM, mechanical engineer at Vanderbilt University.  “The HVAC replacement was taking place within a highly active part of one of our medical research areas, and we wanted to avoid downtime as best as we possibly could. Recognizing that this was a challenging timeframe, particularly for a system of this size, we even had some mechanical contractors decline bid opportunities because of it.”

The mechanical contractor, Nashville Machine, accepted the project bid, which was designed by Smith Seckman Reid (SSR) of Nashville.  Gable and his staff were encouraged by the inclusion of a 259-ton, 100-percent OA, 34,500 CFM ClimateCraft ACCESS knock-down air handling unit, engineered specifically for final assembly at the job site.  The unit, which incorporated foam insulation panels, an IFB Steam coil and a humidifier, would provide more static pressure capability than the existing air handler, and would also include a ClimateCraft FanMatrix fan array tower for built-in redundancy.

“The new air handler provided increased load capacity compared to the existing unit, and also provided numerous design and functionality improvements,” says Gable.  “We were glad to now have built-in redundancy, and the vertical discharge design made management of a non-hazardous odor control issue via a high-velocity plume more efficient.”

According to Craig Barbee, PE, senior mechanical engineer at SSR, the ClimateCraft ACCESS process of custom engineering and manufacturing factory-fabricated, field-assembled air handling units was the reason why the firm identified it as an ideal retrofit solution for the Vanderbilt University project.

“We were looking at a situation in which the customer wanted minimal disruption to the surrounding infrastructure, with an ideal goal of the only deconstruction being that of the HVAC system we were replacing,” Barbee said.  “The ClimateCraft ACCESS custom knock-down air handling unit, along with the support program surrounding it, seemed like the right solution to achieve this goal.”

“The ClimateCraft ACCESS system has been built on a solid foundation of knowledge resulting from many successful installations in the field, and particularly those in which air handler replacement might have been otherwise impossible without major renovation to the surrounding infrastructure,” said Gina Cottrell, vice president of sales and marketing at ClimateCraft, Inc. “The ACCESS support services we provide also represent our best practices in ‘thinking like the contractor’ to save time and money at the jobsite through training, advance planning, and on-the-job support.”