The new plant consists of five condensing boilers rated at 3,000 MBH each (total plant capacity of 15,000 MBH) with a thermal efficiency rating of up to 99%, depending on operating. The building was an excellent application for high efficiency, condensing boiler technology because, as a heat pump system, the original hydronic heating system design was to operate at low water temperatures.

• At 15,000 MBH (450 boiler horsepower), One Rotary Center is home to one of the largest condensing boiler plants in the United States.
• A new mechanical equipment penthouse was constructed on top of the building’s parking garage and immediately adjacent to the existing fourth floor main mechanical room. The existing electric boilers were demolished and the heating and cooling systems were segregated and control schemes revised to operate in a more conventional manner.
• More than 2,000 tons of GHG emissions were saved, a reduction of 80% by using the condensing boiler plant instead of the old equipment combination of heat pumps and electric boilers.
• The estimated utility cost savings during the first season of operation was calculated to be approximately $127,000, based on an avoided electrical cost of $206,000 and an added natural gas cost of $79,000.