York YK-EP utilizes a patent-pending mechanical compression economizer cycle to boost performance over conventional chiller platforms. The water-cooled centrifugal chiller uses a York OptiSpeed variable-speed drive, which can accept medium or high voltage power, trimming average annual energy consumption up to 30 percent. The chiller is able to operate with 50°F (10°C) low entering condenser water temperature (ECWT) compared to 75°F (23.9°C) of other chillers, trimming instantaneous energy consumption as much as 50 percent. Additionally, in facilities with multiple YK-EP chillers, energy savings can be accomplished with series-counterflow arrangement. This reduces the compressor work needed on each chiller, cutting system energy use by as much as 8 percent at design conditions, says the manufacturer.