Getting out of Hot Water
Rahway Branch YMCA
By JOHN PARRIS FRANTZ
While one of the most common complaints of swimmers entering a pool is "cold" water, summertime swimmers at Rahway Branch YMCA in Rahway, N.J., regularly voiced criticism that the 200,000-gallon indoor pool was too hot.
The 42-foot-by-75-foot pool's water would start a hot summer day at the desired set point of 84ºF, but water temperatures regularly surpassed 90ºF because of no air conditioning or modern mechanical dehumidification, the latter of which had yet to be invented when the pool addition building was constructed 28 years ago.
"It wasn't a real comfortable swimming experience on hot days," says Clark Lagemann, director of property and technology management for the YMCA of Eastern Union County in Elizabeth, N.J.
Armed with a $500,000 budget earmarked for a variety of improvements including new lighting, electrical upgrades, re-coated pool surface, epoxy-painted walls and ceiling, plus the replacement of the chemical feeder, filter pump, motor and strainer systems, the Y set out to make the indoor air quality (IAQ) as superior as the pool functions.
The HVAC equipment retrofit is expected to provide a quick payback through energy-savings. Besides economical benefits, the additions of air conditioning and dehumidification have helped improve attendance figures by enhancing the 6,230-square-foot natatorium's overall aesthetics, comfort and IAQ.
The Y relied on the engineering design recommendations of Phil Nicholson, a sales/engineer for Stillwell-Hansen Inc. in Edison, N.J., a local manufacturer's representative with broad expertise in natatorium IAQ. The mechanical contractor on the project was UniTemp Corp. in South Plainfield, N.J., a wholly-owned subsidiary of Pepco Building Services in Alexandria, Va.
After seeing Rahway's need for space heating, air conditioning and dehumidification as well as pool heating, Nicholson's design specified a packaged HVAC heat-recovering dehumidifier from Dectron Inc. in Roswell, Ga., that would cover all IAQ needs in one unit.
"To get the most for their money, they really needed one-stop-shopping and a custom-manufactured heat-recovery dehumidifier would give them everything in one package with single-source responsibility," Nicholson says.
The retrofit included replacing the natatorium's outdated HVAC system consisting of make-up air handlers that circulated air and depended greatly on exhausting and bringing in large quantities of outside air. While adequate for ventilation, exhausting and replacing a huge volume of air instead of reconditioning isn't energy-efficient by today's standards. Additionally, introducing hot, humid outside air without conditioning it in the summer only worsened the indoor air comfort concerns. Conversely, the DRY-O-TRON Model RS-120 dehumidifies both room air and outdoor air, while simultaneously conditioning them to either cool or heat the space.
The energy recovered by the dehumidification process, plus the compressor heat, provides free pool water and space heating. While the dehumidifier's heat recovery provides 100 percent of the pool water heating the majority of the year, the package also includes a 512,000-Btu hot-water boiler as a backup for extremely cold days. While the Y's existing 512,000-Btu boiler previously heated the pool air and water, it has been retained for only a backup role to the building's hot-water heating system. The combination of integral gas hot-water heating and dehumidification are controlled and operated by the Dectron unit's Supervisaire microprocessor, which assures single-source responsibility.
Besides the gas-fired boiler, Nicholson also specified a 9,500-cfm purge mode exhaust fan that provides a quick air change in 10 minutes for the Y's routine super-chlorination treatments of the pool water.
Nicholson purposely specified the Dectron unit for the identical 11,000-cfm capacity of the previous HVAC air-handling units and calculated adjustments for static pressure. This allowed the retrofit to use the existing 65-inch-by-24-inch-rectangular stainless-steel sheet-metal ductwork trunk line and its branches, thus saving the project approximately $100,000 in stainless-steel materials and installation labor.
"We were lucky there are no windows to condition, or we would have needed a larger dehumidifier and new ductwork," Nicholson says.
While the existing ductwork was re-used, UniTemp's structural engineering team examined the existing roof and determined additional supports in truss webs were needed to support the rooftop's dehumidifier, according to James Paslowski, project manager of UniTemp. Stainless-steel ductwork connecting the dehumidifier to the existing ductwork was custom fabricated and run through a loft section between the pool area and rooftop.
Today the Rahway Y sports one of the area's most modern, efficient and state-of-the-art pools with indoor air quality that rivals the most recently built facilities.