A gas convection heating apparatus has a back wall of apparatus, this is bearing structure of apparatus. A heat exchange unit of apparatus has wall with round opening, two rings in the form of pipes with different diameters, one of those is pipe-ring, system of partitions that has not less than two partitions, one of those has flat form and includes round opening that is arranged with displacement from center of the partition to its upper part, and the other partitions have round planar shape and have round openings arranged without displacement from centers of those partition. An air exchange unit has air splitter that has round flat form and elements for fixation of the air-exchange unit. Besides that heat exchanger has from one to two working sections and is arranged as hermetic body of apparatus that at same time is combustion chamber of apparatus. Front wall of apparatus has opening for inspection window, opening for installation of ignition burner, safety thermo-element and spark electrode. On front wall of the heat exchanger there is depression in rectangular form. Besides that opening for discharge of combustion products that is placed on the back wall of the heat exchanger is made round and placed in the upper central part of the back wall of the heat exchanger, and under it, on the back wall of the heat exchanger, segment opening is placed for supply of atmospheric air, at that center of circle from which segment opening is formed is displaced vertically down with respect to center of round opening for supply of atmospheric air. To the face plane of the back wall of the heat exchanger at edges of round opening cylindrical branch pipe is attached, for discharge of combustion products from the heat exchanger, and cylindrical flange is attached for supply of flow of atmospheric air in such way that its lower part at its inner plane coincides with segment opening. A branch pipe for discharge of combustion products is placed in flange for supply of flow of atmospheric air by principle “pipe in pipe”. The heat exchanger has inner structural elements for heat transfer and for directing flows of atmospheric air and combustion products, those are arranged as inner walls of the heat exchanger each of which has not less that one working plane, and such inner walls of the heat exchanger are attached to vertical side and/or to lower, and/or to upper, and/or to back and/or to front walls of the heat exchanger. Outer shell of the apparatus is arranged as outer case that has ventilation openings. The technical result of the invention is in provision of most optimal way for motion of flow of atmospheric air and for effective burning of gas, and for motion of combustion products of gas-air mix from heat exchanger to outside; increase of rate and effectiveness of transfer of heat energy from heat flows to air masses circulating in premises being heated; provision of tightness of apparatus, and as a result increase of the performance index up to 87%; provision of ecological purity, efficiency and safety of use of the apparatus.