Outdoor unit for the production of chilled water, equipped with variable speed screw compressors with integrated inverter, specifically designed for the use of the R513A refrigerant. The units are equipped with helical fans, microchannel condensation coils, tube beam evaporator and electronic expansion valve. The base, the structure and the panels are made of galvanised steel sheet painted with polyester powders, ensuring robustness and resistance to atmospheric agents. A condensation control device optimises operation according to the operating conditions. Thanks to the careful design of the components and the use of variable speed technologies, the machine ensures maximum energy efficiency, reliability and flexibility in all working conditions.