METHOD FOR CALIBRATING A GAS BURNER

摘要

Method for operating a gas burner, wherein during burner-on phases a defined gas/air mixture having a defined mixing ratio of gas and air is provided to a burner chamber (11) of the gas burner for combusting the defined gas/air mixture within the burner chamber (11). Said defined gas/air mixture is provided by a mixing device (23) mixing an air flow provided by an air duct (15) with a gas flow provided by a gas duct (16). Said air flow flowing is provided by fan (14) in such a way that the fan speed of the fan (14) depends on a desired burner load of the gas burner, wherein the fan speed range of the fan (14) defines a modulation range of the gas burner. Said mixing ratio of gas and air of the gas/air mixture is controlled over the modulation range of the gas burner by a pneumatic controller (24) on basis of a pressure difference between the gas pressure of the gas flow in the gas pipe (16) and a reference pressure, wherein either the air pressure of the air flow in the air duct (15) or the ambient pressure is used as reference pressure, and wherein the pressure difference between the gas pressure and the reference pressure is determined and controlled pneumatically. During burner on phases the combustion quality is monitored on basis of a signal provided by a combustion quality sensor like a flame ionization sensor (13) or an exhaust gas sensor (26). The signal provided by the combustion quality sensor is used to detect tolerances of the pneumatic controller (24) and/or a potentially changing behaviour of the pneumatic controller (24) by checking if the combustion quality is inside or outside a defined combustion quality range; wherein when the combustion quality is inside the defined combustion quality range, the mixing ratio of gas and air of the gas/air mixture is kept constant; and wherein when the combustion quality is outside the defined combustion quality range, the mixing ratio of gas and air of the gas/air mixture is changed by adjusting a setting of a gas throttle (17) positioned within the gas duct (16). Influences of tolerances of the pneumatic controller (24) and/or of a potentially changing behaviour of the pneumatic controller (24) become compensated such that the modulation range can be extended to lower loads.