Guests complained of drafts, excessive air noise, and hot spots from the circa-1930s air-conditioning system. The outdated system was incapable of evenly distributing air from the original seven 40- by 24-inch wall grilles in the expansive room.
Solving this problem became the responsibility of Ray Shelton, manager of Cinergy's Site Services East division.
Retrofitting the air-distribution system with conventional ceiling ducts and registers at an estimated $100,000 was cost prohibitive. Also, inaccessibility above the dropped ceilings and costs to update lighting systems were of concern. Shelton and mechanical contractor DeBra-Kuempel, a recently acquired division of Norwalk, Conn.-based Emcor, recommended a fabric air-distribution system.
DuctSox specifiedDeBra-Kuempel's service manager Michael Jay Ester, and manufacturer's representative Jeff Johnson, territory manager at York International's Tri-State branch in Cincinnati, suggested the D-Shape model fabric duct by DuctSox Inc. of Dubuque, Iowa.
The D-Shape's linear mesh diffusers run the entire length of each of seven duct runs and provide a draft-less air flow that disperses air down to the occupancy zone of the 20-foot-high, 2,500-square-foot room, according to DuctSox officials.
Approximately 15 percent of the air is designed to permeate through the Comfort-Flow fabric. Because the duct suspension system is designed to accommodate connections to dropped ceiling grid hardware, installation time was less than for conventional duct, according to Ester, who coordinated the project.
The custom-designed sheet metal plenum transitions between the duct and existing wall grilles were designed by licensed professional engineer John Kuempel Jr., a vice president at DeBra-Kuempel. The 20-gauge sheet metal plenums collect air from the wall grilles and direct it upward to a connection for the fabric duct.
Because of the ceiling contour, the outlets include a 15-degree downward angle offset for proper alignment into the fabric duct. The plenum also enables a horizontal offset, so each duct run avoids existing ceiling lighting fixtures. Each takeoff uses a round, 16-inch-diameter sheet metal adaptor with internal balancing dampers to direct air into the end-inlet orientation of the D-shaped fabric duct.
Cinergy saved additional costs by having DeBra Kuempel validate the performance of the original custom-constructed air handler, for which no design data was available.
"We size the fabric duct based on the antiquated air handler's maximum performance based upon coil area," said Kuempel. "The fabric-duct air-throw performance was checked with the installation height from occupants to assure draft-free performance."