Abstract: A heat exchanger includes: a cooler/heater, an evaporator and a condensate separator, provided with inlet lines and outlet lines through which flows develop in countercurrent to each other for obtaining through the cooler/heater an incoming flow of hot and humid air and an outgoing flow of cooled cold air. The cooler/heater, the evaporator and the condensate separator are independent units from each other joined by a connection for defining a single-block body on whose outer surface inlet lines and outlet lines are provided. A first conduit places in communication the outlet line with the second inlet line; a second conduit places in communication the first outlet line with the first inlet line; and a third conduit places in communication the first outlet line with the first inlet line. The conduits project from the outer surface that delimits the single-block body.