Outdoor reversible heat pump for the production of chilled and heated water. The PRM uses the natural refrigerant R290 with a GWP of only three. Its modular architecture, up to nine units that can be coupled, together with the system with four scroll compressors on two circuits, makes the system more reliable and guarantees continuity of operation. Designed to meet the air conditioning needs of residential, commercial or industrial complexes, it operates at full load up to -20°C of external air temperature in the winter season, up to 48°C in the summer season and produces hot water up to 75 °C. It is available in high efficiency and high efficiency silenced versions.