Abstract: An air mixing unit for a ventilation system includes a housing with a control door to control at least one inlet air stream, a mode door to control at least one outlet air stream and air passages for supplying air through said mixing unit. An air duct system that is arranged to be attached to said control door funnels air from one side of said mixing unit to the other.

Abstract: A heat exchanger has flat tubes arranged in parallel to one another and at a distance from one another. The flat tubes are provided in the area of their ends with connection openings to adjacent flat tubes to avoid difficulties with respect to the tight closing of the open front ends, massive slide-in parts are introduced into the open tube ends. The walls of the flat tubes at least on the narrow sides against the slide-in parts. The slide-in parts therefore act as adapting pieces which determine the final form of the tubes. They cause a tight and pressure-resistant connection after the soldering.