Along with 2,500–3,500 ton capacity, YORK YK-EP (Efficiency Plus) features mechanical compression economizer cycle that optimizes performance. Energy conservation is fostered by YORK OptiSpeed™ variable speed drive, which accepts medium or high voltage power, as well as ability to operate with 50°F low entering condenser water temperature (ECWT). Further energy savings can be realized via series-counter flow arrangement, which reduces compressor work needed on each chiller.