Method for operating a gas burner appliance

A method for operating a gas burner appliance comprising:

• providing, during burner-on-phases, defined gas/air mixture having a defined mixing ratio of gas and air to a burner chamber of the gas burner appliance for combusting the defined gas/air mixture within the burner chamber,
• wherein the defined gas/air mixture is provided by a mixing device mixing an air flow with a gas flow,
• wherein the mixing device has at least two Venturi nozzles connected in parallel;
• wherein the air flow is provided by a fan in such a way that a fan speed of the fan depends on a desired burner load of the gas burner appliance,
• wherein a fan speed range of the fan defines a modulation range of the gas burner appliance,
• wherein the defined mixing ratio of gas and air of the gas/air mixture is controlled over the modulation range of the gas burner appliance by a gas regulating valve,
• wherein the gas regulating valve has a pneumatic controller controlling the mixing ratio of gas and air on the basis of a pressure difference between a gas pressure of the gas flow in a gas pipe and a reference pressure,
• wherein either an air pressure of the air flow or an ambient pressure is used as the reference pressure, wherein the pressure difference between the gas pressure and the reference pressure is determined and controlled pneumatically,
• wherein, during burner-on-phases, the combustion quality is monitored on the basis of a signal provided by a combustion quality sensor,
• wherein the defined mixing ratio of gas and air of the defined gas/air mixture can be calibrated on the basis of the signal provided by the combustion quality sensor, by adjusting a position of a throttle, and;
• wherein the calibration of the gas/air mixture is performed in such a way that at least one of the Venturi nozzles of the mixing device is closed while at least one of the Venturi nozzles of the mixing device is opened.