Despite Tight Budget, Pool Project Comes Out on Top
"The challenge in the natatorium was to provide a high-performance dehumidification, heating, and cooling system that also met the client's energy-efficiency and budgetary requirements," says Michael Toy, P.E., Ph.D. Toy is chief mechanical engineer for mechanical/electrical/plumbing consulting engineering firm, Concord Atlantic Engineers Inc., (CAE) (West Atlantic City, NJ). A five-year-old company, CAE evolved from the former, well-known Harold Cohen Associates (Pleasantville, NJ).
Room for Reduced CostsOne example of cost cutting is Toy's choice of putting the pool space's Dry-O-Tron(r) RB-150 heat recovery dehumidifier, manufactured by Dectron Internationale (Roswell, GA), on the 11,000-sq-ft natatorium's roof. With school building costs surpassing $250/sq ft, the roof placement of the dehumidifier saved the school district more than $25,000 in mechanical room space.
Other cost cutting measures instituted by CAE and project architect, Faridy Veisz Fraytak, PC, (Trenton, NJ), included the limitation of windows normally found in natatoriums. With its low insulation value, glass attracts more moisture than masonry materials and presents more of a cooling and heating load on hvac equipment. The reduction of windows in the design resulted in smaller sized equipment that will in turn generate lower operational costs.
Safety was also a key issue in the roof placement of the dehumidifier package, which includes an on-board natural gas-fired boiler option. Keeping combustion away from chemicals and flammable gases commonly used with indoor pools also eliminates premature boiler burner corrosion. Besides removing 150 lb of moisture/hr to maintain a comfortable 50% to 55% relative humidity, the Dry-O-Tron also heats the pool water to 80 degrees F and cools or heats the pool area to a design temperature of 82 degrees.
The energy a pool loses through evaporation represents approximately 95% of its annual water-heating requirement. The Dry-O-Tron captures this heat as a by-product of the dehumidification process and creates a thermal flywheel, returning the energy lost through evaporation back into heating the pool water. This energy cycle is 100% efficient since all the moisture is converted into sensible heat for recycling. Furthermore, the electrical energy required to operate the system is also converted into sensible heat and contributes to space heating. The whole system's energy is recycled. All of these setpoints are monitored and controlled through an on-board microprocessor controller that interfaces with the school's existing Tracer System building automation system by Trane (Tyler, TX).
Other equipment employed on the project includes a 650 MBtuh Lochinvar Corp. (Nashville, TN) backup boiler for pool water heating and Trane rooftop air conditioners for separate locker room hvac. "In a pool project, I always try to separate things like mechanical rooms and locker rooms from the pool air," Toy says.
Lightening the LoadThe air distribution, which consists of five 24-in.-dia galvanized steel duct runs that reduce down to 14 in. to shave metal costs, was closely integrated into the natatorium's indirect lighting scheme that was designed to cut glare. The duct was strategically located to blend into the ceiling and reflect the ceiling fixture lamps based on a photometrics analysis test. The indirect lighting treatment effectively cuts pool surface glare while simultaneously squeezing out the most watts per fixture.
The ceiling ductwork also reflects light because of the off-white epoxy chosen to camouflage it. Additionally, the epoxy coating was field-applied internally and externally for corrosion resistance by Liber Rich & Sons, (Pleasantville, NJ), a division of PSE&G Energy Technologies (Newark, NJ) and its subcontractor, Kiker Sheet Metal Corp., (Pleasantville, NJ).
Liber Rich, the project's mechanical contractor, installed the dehumidifying equipment and manufacturer's representative Sass, Moore & Associates (Woodbury, NJ), helped with the equipment start-up and calibration. The return air ductwork is hidden in two wall chases with 16-ga galvanized steel grilles by Ruskin, (Kansas City, MO), mounted 18 in. off the floor. Each return delivers 7,500 cfm of air back to the dehumidifier, which in turn is mixed with a minimum of 4,400 cfm of outside air in accordance with ASHRAE standards.
Toy's design combined with Dectron's dehumidifying equipment has been a big hit at the school. "My experiences in the past have found indoor pools to be extremely hot and humid," says Dr. Ed Coyle, superintendent for Mainland Regional's school district. "I was surprised to find out how comfortable a pool area could be. The room and water temperatures always seem to be in balance. Our swimmers are very pleased with the pool and deck area." All players in the project feel confident they gave the school district the best value for its dollar while not sacrificing functionality. "The key to this project was to cut costs wherever possible in order to add as many of the school district's wish list items as possible," adds Toy.ES