Abstract: Apparatus for recovering heat or cooling from a room space and ventilating it, consisting of heat accumulators in which the outgoing air releases its heat and from which the incoming air picks up heat or vice versa and which are alternatively connected by one end with the exhaust duct and intake duct of the room space, the direction of flow in these ducts being the same all the time under control by two flaps, and the opposite ends of the heat accumulators being connected to the fresh air intake duct and the outgoing exhaust duct, the direction of flow being the same in these latter ducts all the time under control by the two flaps. The heat accumulators consist of elements which may be added or taken off two and two, in accordance with the required capacity of the apparatus, and that the intake and exhaust ducts carried to the room spaces can correspondingly in a manner known in itself be lengthened or shortened by means of branch pieces.

Abstract: A means for recovering the heat of a room space and for ventilation, consisting of at least two heat accumulators, to which the outgoing air delivers its heat and from which the incoming air takes up heat, and each of which has one end connected to the room space outflow duct and inflow duct, in which ducts the direction of flow is always the same under control by a flap. The opposite ends of the heat accumulators have been connected to the fresh air intake duct and to the outgoing exit duct, in which ducts the direction of flow is always the same under control by another flap.