Southside Regional Medical Center, an acute care general hospital in Petersburg, Va., has more than 200 physicians and 1,400 employees. It also had an aging chiller plant, one that was showing decreases in both reliability and efficiency.

CEK Engineering, now Teng Engineering, an architect and the owner of the building conferred on a plan to modernize the cooling plant. Its two centrifugal chillers were nearly 30 years old and had nominal ratings of 800 and 400 tons. However, some tubes had deteriorated to the point that they had to be plugged. Others had corrosion or wear problems causing increased numbers of tube leaks. According to Ted Large, director of plant services at the facility, the combined nameplate rating of 1,200 tons had deteriorated to less than 1,000 tons. The refrigerant in use was R-11.