YMCA's Cool Retrofit Also Cuts Energy Costs
The 42-foot-by-75-foot pool's water would start a hot summer day at the desired set point of 84 degrees F, but water temperatures regularly surpassed 90 degrees because the building had no air conditioning or modern mechanical dehumidification, the latter of which had yet to be invented when the addition housing the pool was constructed 28 years ago.
"It wasn't a real comfortable swimming experience on hot days," said Clark Lagemann, director of property and technology management, 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, recoated pool surface, epoxy-painted walls and ceiling, plus the replacement of the chemical feeder, filter pump, motor, and strainer systems - the YMCA set out to make the indoor air quality (IAQ) as superior as the pool functions.
One Units Covers AllThe HVAC equipment retrofit is expected to provide a quick payback through energy savings. Besides economic benefits, the addition of air conditioning and dehumidification has helped improve attendance figures by enhancing the 6,230-square-foot natatorium's overall aesthetics, comfort, and IAQ.
The YMCA relied on the engineering design recommendations of Phil Nicholson, who at the time was a sales engineer for Stillwell-Hansen Inc., Edison, N.J. Nicholson was the local manufacturer's representative with broad expertise in natatorium IAQ. He is now working for G&C HVAC Equipment Sales in Scotch Plains, N.J., a Dectron manufacturer's rep.
The mechanical contractor on the project was UniTemp Corp., South Plainfield, N.J.
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, which he thought 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," said Nicholson.
The retrofit included replacing the natatorium's outdated HVAC system, consisting of make-up air handlers that circulated air and depended greatly on exhausting and bringing in large quantities of outside air.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 it isn't energy efficient by today's standards. Additionally, introducing hot, humid outside air without conditioning it in the summer would only worsen the indoor air comfort concerns.
Conversely, the Dry-O-Tron Model RS-120 is designed to dehumidify both room air and outdoor air, while simultaneously conditioning them to either cool or heat the space.
Using a standard air conditioning system for a pool environment, the life expectancy would probably be half the life of a standard dehumidification unit. As a standard air conditioner evaporator coil is only three to four rows, it is not necessarily designed to handle the high moisture levels in a pool environment and maintain a comfortable relative humidity level of between 50 percent and 60 percent. However, Dectron's standard dehumidifying coil is an eight-row, HyPoxy-coated coil.
Free HeatingWith this system, 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 YMCA'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.
Besides the gas-fired boiler, Nicholson also specified a 9,500-cfm purge mode exhaust fan, designed to provide a quick air change in 10 minutes for the YMCA's routing 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-23-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," said Nicholson.
While the existing ductwork was reused, 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, Uni-Temp. Stainless steel ductwork connecting the dehumidifier to the existing ductwork was custom fabricated by UniTemp and run through a loft section between the pool area and rooftop.
Today, the Rahway YMCA sports one of the area's most modern, efficient, and state-of-the-art pools with IAQ that rivals the most recently built facilities.
Publication date: 08/15/2005