METHOD FOR OPERATING A GAS BURNER APPLIANCE

Method for operating a gas burner appliance (10). During burner-on-phases a gas/air mixture having a defined mixing ratio of gas and air is provided to a burner chamber (11). Said gas/air mixture is provided by a mixing device (23) mixing an air flow with a gas flow. Said mixing device (23) has at least two Venturi nozzles being connected in parallel. Said air flow is provided by a fan (14) in such a way that the fan speed of the fan (14) depends on a desired burner load. The fan speed range of the fan (14) defines a modulation range of the gas burner appliance (10). Said defined mixing ratio of gas and air of the gas/air mixture is controlled over the modulation range of the gas burner appliance (10) by a gas regulating valve (18). Said gas regulating valve (18) has a pneumatic controller (24) controlling the mixing ratio of gas and air on basis of a pressure difference between the gas pressure of the gas flow in the gas pipe (16) and a reference pressure. During burner-on-phases the combustion quality is monitored on basis of a signal provided by a combustion quality sensor. The defined mixing ratio of gas and air of the gas/air mixture can be calibrated during on basis of the signal provided by the combustion quality sensor, namely by adjusting during calibration a position of a throttle (17). The calibration of the gas/air mixture is performed in such a way that for calibration at least one of the Venturi nozzles (28) of the mixing device (23) is closed while at least one of the Venturi nozzles (28) of the mixing device (23) is opened.