YORK YZ Magnetic-Bearing Centrifugal Chiller

The YORK YZ is a water-cooled centrifugal chiller designed ground-up for R-1233zd(E), a non-flammable (ASHRAE A1) low-pressure refrigerant with a GWP of 1. Where most chillers retrofit low-GWP refrigerants into existing compressor geometry, the YZ was re-optimised from the outset — compressor aerodynamics, heat-exchanger sizing and motor speed were all specified for R-1233zd(E)'s thermodynamic properties, resulting in efficiency gains that straight substitutions cannot match.

Capacity runs from 165 to 1,350 TR (580–4,747 kW), a span that covers mid-large terminal buildings up to the lower tier of district cooling plant. Like the YMC², the YZ uses active magnetic bearings, eliminating oil lubrication and the associated maintenance overhead. At minimum-lift conditions the COP can reach 38 — an extreme figure achievable when condenser and evaporator temperatures are close together, for example during overnight cool-down or mild-climate shoulder seasons.

The variable-speed drive combined with a variable-geometry diffuser allows the machine to shed 35% of annual energy versus fixed-speed, oil-bearing centrifugal alternatives. The unit can operate with condenser water entering below leaving chilled-water setpoint, enabling economiser-mode integration without adding a water-side economiser coil. For procurement engineers in jurisdictions that have announced F-gas or HFC restrictions, or where sustainability certification (LEED, Estidama, GSAS) affects building-permit conditions, the YZ provides a compliant chiller plant with no future refrigerant transition risk.