Abstract: Combined regulation of the power supplied by the conditioner and of the air flow rate of the conditioner is carried out so as to maintain the temperature gradient between air entering and air leaving the same conditioner high, in order to allow perfect functioning of displacement system (without mixing) in any condition of service.

Abstract: A unit comprises a refrigerating circuit (30), at least part of a primary circuit (110), and connections (151, 152) for a user's circuit (120). The refrigerating circuit comprises an evaporator (E), a compressor (31), a condenser battery (C), and an expansion valve (34), and connection lines. The primary circuit extends through the evaporator and through an air-cooled “free-cooling” battery (FC). To allow a variable flow through the free-cooling battery, though maintaining the flow rate constant through the evaporator, the primary circuit (110) comprises a bypass line (140) extending between an outlet line from the evaporator and an inlet line to the evaporator, and a storage tank (A) on said bypass line.