Editor's Note: In this new section of PM Engineer's Web site, we will be providing manufacturer's case studies of unique projects and the equipment that is used to complete them. Manufacturers are encouraged to submit their unique case studies to Kelly Johnson, Managing Editor, at kellypme@aol.com.

It takes something extraordinary to get noticed on the strip in Las Vegas, NV. The Stratosphere Casino Hotel & Tower has a 12-story "pod" atop a 1,149-foot needle-like structure. A revolving restaurant and the world's highest roller coaster are two of the main attractions at the top of the tower.

The Stratosphere Tower, which opened in April 1996, is the tallest freestanding tower in the United States. Thrill seekers can take a wild ride on the High Roller, with its 865-foot track wrapping around the top of the pod, or the more adventuresome can experience the feeling of zero gravity on The Big Shot, which shoots 160 feet vertically above the pod.

In addition to the main tower, the original plans for the property included a 24-story hotel tower expansion. The expansion project was put on hold in late 1996, but business has continued to be brisk; the hotel has hosted more than 12.5 million visitors in the last five years. In April 2000, construction resumed on the tower expansion project and will be completed in late 2001. Estimated at $75 million, the plans include the 24-story hotel tower with 1,000 new guest rooms, 100 suites, a 67,000-sq.-foot pool and a 300-seat coffee shop.

Installation in the Main Tower

With the Stratosphere Tower's unique shape, space is scarce. This is especially true in the 12-story pod, which houses a revolving restaurant, indoor and outdoor observation decks, a 220-seat lounge, retail space, three wedding chapels, meeting rooms and two "safe area" floors for use in an emergency.

Supplying hot water and hydronic heat for the hundreds of people that would be dining and sightseeing was going to be a challenge. The engineering and mechanical teams responsible for the Stratosphere Tower's hvac system faced working within a hollow core that is 3 feet deep by 15 feet wide.

"The decision to install the water heating at the top of the tower was based on cost and space limitations," said Kris Kalkowski, a design engineer with Dunham Associates. "There was simply not enough space in the inner sphere for the required supply and return piping." The drainage, chilled water and domestic water systems were also installed in the sphere.

The next question was how to fit the necessary water heater and boilers into the limited space of the pod. Kalkowski investigated a number of possible products, but had to work within the Nevada State Boiler Code, which requires that boilers have a minimum 3-foot clearance for maintenance. The mechanical room's sloping walls made this a tough specification. Kalkowski decided on three Lochinvar Power-Fin boilers and a Power-Fin water heater to meet the specifications.

The boilers were chosen for their ability to supply the three million Btu/hr of heat necessary for the restaurant and lounge. And the water heater offered the capacity to supply in excess of 1,000 gallons of hot water per hour to meet the system's hot water demands. With the overall complex design of hvac system, the venting capabilities the boilers also had to be considered. "The combination of Lochinvar's direct vent and intake worked well with the sloping exterior metal panels and provided minimal penetration," explained Kalkowski.