A method for control of a fuel-air mixture of a system, which in particular is a gas heater, wherein the system has a mixing device for mixing a fuel with air in order to form the fuel-air mixture, an actuator arranged in the flow direction of the fuel upstream of the mixing device and driven by a control variable for control of a fuel mass flow and a differential pressure sensor for detecting a differential pressure between a pressure p2 of the fuel upstream of the mixing device and downstream of the actuator with regard to a reference pressure in the flow direction of the air upstream of the mixing device as an actual value, wherein the actual value detected by the differential pressure sensor changes with a change in position of the actuator after a dead time and with a gain factor which depends on the control variable causing the change so that the system behaviour can be described by the dead time and the gain factor, characterised in that the control variable is determined by driving the actuator in a first method phase for identification of the system behaviour with a standard controller in order to align the mean actual value to a target value, wherein the control variable and the actual value can each swing about the target value by the dead time and the gain factor with an amplitude and a frequency, wherein a course of the actual value and a course of the control variable are detected during the first method phase for identification of the system behaviour and the gain factor as a function of the control variable and the dead time are determined therefrom, wherein the control variable, after the dead time and the gain factor have been determined, in a second method phase for model-predictive adaptive control of the system is determined with a model-based controller in particular having a Smith predictor, which takes into account the gain factor and the dead time, in order to align the actual value to the target value so that the control variable has to be changed less often and less severely in the second method phase compared to the first method phase. wherein the system has a mixing device for mixing a fuel with air in order to form the fuel-air mixture, an actuator arranged in the flow direction of the fuel upstream of the mixing device and driven by a control variable for control of a fuel mass flow and a differential pressure sensor for detecting a differential pressure between a pressure p2 of the fuel upstream of the mixing device and downstream of the actuator with regard to a reference pressure in the flow direction of the air upstream of the mixing device as an actual value, wherein the actual value detected by the differential pressure sensor changes with a change in position of the actuator after a dead time and with a gain factor which depends on the control variable causing the change so that the system behaviour can be described by the dead time and the gain factor, characterised in that the control variable is determined by driving the actuator in a first method phase for identification of the system behaviour with a standard controller in order to align the mean actual value to a target value, wherein the control variable and the actual value can each swing about the target value by the dead time and the gain factor with an amplitude and a frequency, wherein a course of the actual value and a course of the control variable are detected during the first method phase for identification of the system behaviour and the gain factor as a function of the control variable and the dead time are determined therefrom, wherein the control variable, after the dead time and the gain factor have been determined, in a second method phase for model-predictive adaptive control of the system is determined with a model-based controller in particular having a Smith predictor, which takes into account the gain factor and the dead time, in order to align the actual value to the target value so that the control variable has to be changed less often and less severely in the second method phase compared to the first method phase.