Burner for fuel firing, having - at least one heat exchanger, - at least one fuel supply for supplying fuel, - at least one combustion air inlet for the supply of combustion air, - at least one exhaust gas recirculation for recirculating exhaust gas, and - at least one fuel element for burning supplied fuel in combustion air while obtaining exhaust gas, wherein the burner alternates cyclically between at least a first and a second configuration, wherein in the first configuration, the combustion air inlet passes through a first subsection of the heat exchanger, wherein the first subsection releases heat absorbed therein to the supplied combustion air, and the exhaust gas recirculation passes through a second subsection of the heat exchanger, wherein the second subsection absorbs heat from the exhaust gas, in the second configuration, the combustion air inlet passes through the second subsection of the heat exchanger, wherein the second subsection releases heat absorbed therein to the supplied combustion air, and the exhaust gas recirculation extends through the first subsection of the heat exchanger, wherein the first subsection receives heat from the exhaust gas, wherein the burner comprises a rotor, wherein the rotor is configured in a first rotational position associated with the first configuration to pass the combustion air through the first subsection of the heat exchanger and the exhaust gas through the second subsection of the heat exchanger, and in a second rotational position associated with the second configuration to pass the combustion air through the second subsection of the heat exchanger and the exhaust gas through the first subsection of the heat exchanger, wherein the fuel element is designed to rotate with the rotor, wherein the rotation of the fuel element causes at least one fuel outlet opening to be directed in the direction of the preheated combustion air emerging from the heat exchanger, characterized in that in that the burner has a chamber and the rotor has a lead-through, and the lead-through for passing the combustion air is separated from the chamber for discharging the exhaust gases, the active subsections (A, B) of the heat exchanger are determined by the division of the lead-through and of the chamber and the position of the rotor, and in that the subsections (A, B) of the heat exchanger which serve for heating the combustion air and for cooling the exhaust gases are changed constantly and continuously and merging into one another by the rotation of the rotor. - at least one heat exchanger, - at least one fuel supply for supplying fuel, - at least one combustion air inlet for the supply of combustion air, - at least one exhaust gas recirculation for recirculating exhaust gas, and - at least one fuel element for burning supplied fuel in combustion air while obtaining exhaust gas, wherein the burner alternates cyclically between at least a first and a second configuration, wherein in the first configuration, the combustion air inlet passes through a first subsection of the heat exchanger, wherein the first subsection releases heat absorbed therein to the supplied combustion air, and the exhaust gas recirculation passes through a second subsection of the heat exchanger, wherein the second subsection absorbs heat from the exhaust gas, in the second configuration, the combustion air inlet passes through the second subsection of the heat exchanger, wherein the second subsection releases heat absorbed therein to the supplied combustion air, and the exhaust gas recirculation extends through the first subsection of the heat exchanger, wherein the first subsection receives heat from the exhaust gas, wherein the burner comprises a rotor, wherein the rotor is configured in a first rotational position associated with the first configuration to pass the combustion air through the first subsection of the heat exchanger and the exhaust gas through the second subsection of the heat exchanger, and in a second rotational position associated with the second configuration to pass the combustion air through the second subsection of the heat exchanger and the exhaust gas through the first subsection of the heat exchanger, wherein the fuel element is designed to rotate with the rotor, wherein the rotation of the fuel element causes at least one fuel outlet opening to be directed in the direction of the preheated combustion air emerging from the heat exchanger,