Heating pumping installation, in particular with a refrigeration function

Heat pumping installation, implementing cold-exchange and heat-exchange cycles, for refrigeration purposes, of the type incorporating a compression-expansion refrigerant cycle, comprising an evaporation zone prior to compression and a condensation zone after the latter, in which the thermodynamic fluid used in said cycle as well as the fluid used in the cold-exchange and heat-exchange cycles is water, the thermal exchanges occurring during vaporization and respectively condensation between these last two cycles and said refrigerant cycle being direct without the use of exchange surfaces, and the cold produced by this installation usually being at a temperature in excess of 0° C. or at a negative temperature, wherein the refrigerant cycle is operated on the basis of a dynamic compression in a compressor having wheels with two separate compression stages linked to one another by at least one thermal exchange zone and contained in a confinement enclosure for vapor which is hermetically sealed and thermally insulated, the wheels of these two stages being mounted directly on the opposite ends of the shaft of a common, sealed, variable speed electric motor disposed inside said enclosure between these stages.