MILWAUKEE — Hoisting a 30-ft-long, 20,000-lb Dry-O-Tron® dehumidifier sideways into the semi-completed, $40 million Hilton Milwaukee City Center expansion was a rigging challenge for mechanical contractor Downey Inc. and general contractor, Mortensen Construction.

The huge, 50,000-cfm unit — one of the world’s largest — will dehumidify the Hilton’s new three-story, 20,000-sq-ft indoor water theme park.

Consulting engineer firm Arnold & Sheridan, Inc., Brookfield, Wis., took advantage of Dectron’s capabilities of building and factory-testing one unit with 110 tons of total cooling capacity.

While bulky to install, the single unit is expected to save owner-franchisee Marcus Hotels & Resorts, Milwaukee, tens of thousands of dollars in initial costs.

Instead of two or three smaller units, the one large Dry-O-Tron DS-482 will require less duct fabrication and piping, and it will reduce mechanical room space allocated for dehumidification.

Indoor Hilton water theme park

The “Paradise” water theme park was designed by Howard Fields & Associates, Sausalito, Calif., in conjunction with the hotel’s architect, Kahler Slater, Milwaukee. The room simulates a South Pacific Island getaway in the heart of the Midwest Express Convention Center district.

It features a 4,500-sq-ft main swimming pool that emulates a lagoon; twin water slides (75 and 125 ft long); 100-sq-ft hydrotherapy spa; and a 600-sq-ft children’s pool.

The pool includes mushroom-shaped water sprayers, a cascading wall of water, jungle gyms, bridges, slides, and tunnels.

“Paradise is an exciting addition to Milwaukee’s growing list of attractions,” said Gerald Rappaport, general manager of the Hilton Milwaukee City Center. “The 20,000-sq-ft indoor water theme park is a first for the Midwest, and a one-of-a-kind facility for downtown Milwaukee.”

Evaporation variables

Designing an hvac and dehumidification system for a room with so many evaporative variables was challenging for Arnold and Sheridan’s project leader, Kevin Stefanczyk.

Pools and spas are fairly predictable evaporative sources; however, Paradise has a myriad of swim jets, sprays, swirl pools, water slides, a water cascade, and other “toys.”

When combined with a varying amount of people using the pool plus the water and space temperatures, calculations could have become complicated. With the help of manufacturer rep Robert Burkhardt, sales engineer, CDP Inc., Waukesha, Wis., and Dectron’s evaporative rate software, Stefanczyk calculated the space would need a maximum removal of 482 lb of moisture/hr.

Other equipment on the project, which also includes 4,000 sq ft of meeting rooms and a 14-story tower of 200 hotel rooms, includes individual room heat pumps by ClimateMaster.

Stefanczyk also specified a cooling tower by Baltimore Aircoil, Baltimore, and a hot water reheat system with air handlers and vav boxes by The Trane Company for the meeting rooms and offices.