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Oct. 1, 2009
System simulates Tutu Center's new geothermal loop

During the summer of 2005, The General Theological Seminary began renovating three of its buildings in New York's historic Chelsea neighborhood to house The Desmond Tutu Center, which includes a 60-room hotel, a restaurant, and a conference center.

Wanting a low-cost, environmentally friendly heating-and-cooling system, seminary leaders elected to convert the existing fossil-fuel-fired system to what would become the Northeast's largest geothermal system. In August 2007, the first seven of 20 standing-column wells were drilled.

Needing a way to provide chilled water to new heat pumps until the geothermal wells were completed — in essence, to simulate two geothermal wells that would work with the system's new equipment — without disrupting the center's guests or construction, the seminary turned to Aggreko, provider of rental-power, temperature-control, and oil-free-compressed-air solutions.


The job required large chillers, but nearly all of the on-site space was either under construction or being used for construction-equipment storage.

As construction and permit delays pushed the project into winter, the equipment package expanded to include a heating solution. As equipment was added, space considerations and equipment configuration took on greater importance.

Without air conditioning and heating, meeting and accommodation bookings that had been scheduled months before would have had to have been canceled, meaning a large loss of revenue and negative public relations.


Working with the seminary's staff and construction crew, Aggreko identified sufficient space for the placement of a chiller, generator, and fuel tank at both the north and south points of the construction site. Water was directed through the chillers and the new heat pumps to produce cool air.

For winter heating, a portable boiler was ruled out because of space. Aggreko's solution included eight tankless water heaters (two on the south side and six on the north), each with a footprint of 3 sq ft. The system included automatic controls to activate the chillers and heaters based on ambient conditions. When heat was needed, the chillers would shut down, and a portion of the circulated water would be heated to 120°F, mixing with remaining water to produce a constant loop-supply temperature of 65°F. Aggreko's system simulated the center's new geothermal loop with a constant source of water at the appropriate temperature.

With Aggreko providing the fueling, engineering and design, and labor needed to install the equipment, the seminary was able to maintain full facility operations, despite significant construction delays.

“Without Aggreko, we could not have undertaken such a large project with such minimal disruption to our guests and neighbors,” Dennis Frawley, redevelopment-project manager for The General Theological Seminary, said.

Information and photograph courtesy of Aggreko.
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