The York model YK-EP Energy Plus large capacity centrifugal chiller features a patent-pending mechanical compression economizer cycle that increases capacity and energy efficiency. The 8,800- to 11,200-kW-capacity chiller gains additional energy savings during off-design conditions since it can use entering condenser water temperatures as low as 55°F. An optional York OptiSpeed variable-speed drive can lower energy use by another 30% each year. These savings, plus its use of sustainable refrigerant HFC-134a, help it earn LEED points for a building. The chiller is also low maintenance, with open motors for quick repairs, alternate tube materials and thicknesses, and hinged water boxes.