Multipass heat exchangers having return manifolds inserts distribution

Multipass heat exchanger comprising: a manifold (40) having a return wall (20), a front wall (58-1) and a rear wall (58-2), a chamber (42) and a collection chamber (48) distribution that are on opposite sides dedicho partition and are in fluid communication, defining said front and rear walls hydraulic, characterized uncanal that said front wall having a plurality of perforations (46) queponen to said hydraulic channel in communication separate hydraulic said plenum chamber and dichacamara distribution.