CHICAGO - The Chicago Board of Education wanted something different for its school's pool-dehumidification system.

The Chicago Board of Education's Cermak School natatorium is maintained at 50% RH.
CHICAGO - Although direct-expansion (DX) units account for 95% of the swimming pool heat-recovery-dehumidifier market, the Chicago Board of Education wanted Primera Engineers Ltd. to design a pool-dehumidification system without refrigerant heat exchangers in the building or in the air stream.

The Board of Education's new state-of-the-art, 110,000-sq.-ft. Cermak Elementary & Teaching Academy includes an attached 45,000-sq.-ft. community center with a swimming pool - all designed by architect De Stefano & Partners Ltd. of Chicago.

Ordinarily, specifying a DX-style dehumidifier would have been an easy task for the community center's 6,000-sq.-ft. recreational natatorium design; however city codes prohibited the use of refrigerant-based equipment because the same building also hosts a day-care center.

"The city doesn't want refrigerant-based equipment around children under 2 years old because they're too young to vacate the building by themselves in the event of a refrigerant leak," explained Michael Belczak, a senior associate and mechanical engineer, and one of 60 design professionals at Primera, a 15-year-old full-service engineering and architecture firm.

Primera's design team found two manufacturers to build a custom heat recovery dehumidifier that would use a few dozen gallons of 42¿F ethylene glycol instead of the customary hundreds of pounds of R-22 refrigerant typically used in dehumidifiers.

The winning manufacturer, Roswell, Ga.-based Dectron Internationale, built a custom dehumidification system to Primera's specifications via manufacturer's representative, Imbert Corp., Niles, Ill.

The system is split into a mechanical room air handler (model "Dry-O-Tron" DG-182), and a 60-ton rooftop chiller (OCS-802-1H2-9, manufactured by its RefPlus division).

While the chiller uses refrigerant, its remote rooftop location poses no threat because the refrigerant and the air stream of the air handler are separated by 30 feet of glycol piping installed by project mechanical contractor, Ortiz Mechanical of Orland Park, Ill.

The energy-conscious Primera specified a recycling dehumidification system that maintains 50% relative humidity by removing up to 200 pounds of moisture per hour, while heating the pool water and heating-cooling the space to 83¿F and 82¿F temperature set points, respectively.

The challenge for Ref-Plus's in-house engineers was fulfilling Primera's project goals of designing a custom air-cooled and water-cooled chiller. The condenser loop hot water is used for pool water heating and air re-heat. Once the pool water and space heating has been satisfied, the chiller rejects heat to the air-cooled condenser.

In winter, heat generated from the chiller process is transferred to the pool area for space heating. If the dehumidification process can't totally supply pool water heating, a back-up 715,000-Btu boiler activates.