Abstract: The invention relates to a device which can be used alternatively to heat and air-condition a space, such as a residential, working, or storage premises or room or any other enclosed area. The inventive device consists of a heating unit (1) comprising a closed firebox (2) with an air circuit which is used to release the calories produced by said closed firebox (2) and an optionally reversible air-conditioning unit, comprising at least two exchangers at least one of which, called inner exchanger, is placed in an inner air circuit that communicates with the exterior by means of the aforementioned calorie-releasing air circuit on the closed firebox to diffuse the air from inside the device externally. At least one of the exchangers shall be placed downstream and preferably at the outlet of the air circuit which is connected to the closed firebox (2).