Booster is a line of transcritical CO2 systems from Arneg that combines medium and low temperature refrigeration in the same unit. Booster is ideal for use in large stores, cash&carries, distribution centres and logistic centres. Booster can be installed indoors or outdoors and comes in open and closed versions, including ones with a sound-proofed technical compartment and on-board control panel. The system incorporates a parallel compressor, a backup unit for the liquid receiver and inverter control systems for the NT1, LT1 and parallel compressors. An ejector can be added as an option. Booster systems can recover heat to produce hot water and heat the store, and can be integrated with the HVAC system to manage the store's energy needs in a more rational manner.