Flat flame burner comprising - a chamber which extends along a central axis and has a combustion air intake opening and an outlet opening, - a burner lance which extends along or parallel to the central axis and has at least two discharge openings, from which the combustion gas can be discharged, the discharge openings being arranged on the burner lance so that the direction of flow of the combustion gas discharged from the discharge openings has a direction of flow, which stands at an angle of >0° and <180° to the central axis, wherein - the chamber has a first sub-chamber, in which the combustion air intake opening is also arranged and the diameter of which or extension of which perpendicular to the central axis remains substantially the same over the extension of the sub-chamber in the direction of the central axis, - at least part of the wall of the first sub-chamber is designed curved at least over a circular arc segment and the combustion air intake opening and a combustion air feed adjoining the combustion air intake opening upstream are arranged and oriented in the region of the curved wall such that a combustion air stream entering through the combustion air intake opening enters tangentially to the bend in the wall, - the chamber has a second sub-chamber, which in the direction of flow of the combustion air adjoins the first sub-chamber, and at the end of which is arranged the outlet opening and the diameter of which or extension of which perpendicular to the central axis increases over the extension of the sub-chamber from the transition to the first sub-chamber in the direction of the central axis toward the outlet opening, - a second discharge opening of at least two discharge openings is arranged on the burner lance in the first sub-chamber characterized in that - a first discharge opening of at least two discharge openings is arranged on the burner lance in the second sub-chamber. - a chamber which extends along a central axis and has a combustion air intake opening and an outlet opening, - a burner lance which extends along or parallel to the central axis and has at least two discharge openings, from which the combustion gas can be discharged, the discharge openings being arranged on the burner lance so that the direction of flow of the combustion gas discharged from the discharge openings has a direction of flow, which stands at an angle of >0° and <180° to the central axis, wherein - the chamber has a first sub-chamber, in which the combustion air intake opening is also arranged and the diameter of which or extension of which perpendicular to the central axis remains substantially the same over the extension of the sub-chamber in the direction of the central axis, - at least part of the wall of the first sub-chamber is designed curved at least over a circular arc segment and the combustion air intake opening and a combustion air feed adjoining the combustion air intake opening upstream are arranged and oriented in the region of the curved wall such that a combustion air stream entering through the combustion air intake opening enters tangentially to the bend in the wall, - the chamber has a second sub-chamber, which in the direction of flow of the combustion air adjoins the first sub-chamber, and at the end of which is arranged the outlet opening and the diameter of which or extension of which perpendicular to the central axis increases over the extension of the sub-chamber from the transition to the first sub-chamber in the direction of the central axis toward the outlet opening, - a second discharge opening of at least two discharge openings is arranged on the burner lance in the first sub-chamber characterized in that - a first discharge opening of at least two discharge openings is arranged on the burner lance in the second sub-chamber.