Method and controller for operating a gas burner appliance

A method for operating a gas burner appliance,

• by providing during an actual burner-on-phase of the gas burner appliance in request to an actual nominal heat demand a flow of a gas/air mixture (M) to a burner chamber of the gas burner appliance, the gas/air mixture (M) having a defined mixing ratio of gas (G) and air (A) needed for a regular combustion of the gas/air mixture (M) within the burner chamber,
• wherein the gas/air mixture (M) is provided by a mixing device of the gas burner appliance mixing an air flow with a gas flow,
• wherein the air flow or the flow of the gas/air mixture is provided by a fan of the gas burner appliance in such a way that a fan speed of the fan depends on the actual nominal heat demand of the gas burner appliance (10, 10′),
• wherein a fan speed range of the fan defines a modulation range of the gas burner appliance (10, 10′),
• wherein said defined mixing ratio of gas (G) and air (A) of the gas/air mixture (M) is controlled by a controller using as input a signal provided by a sensor and providing as output a control variable for an electric or electronic gas flow modulator in order to keep the mixing ratio of gas (G) and air (A) of the gas/air mixture (M) at the defined mixing ratio over the modulation range of the gas burner appliance, wherein:
• if the actual nominal heat demand of the gas burner appliance is no longer present, the following steps are automatically executed in order to set-up the gas burner appliance for an upcoming burner start:
• decrease during the actual burner-on-phase the fan speed of the fan to a defined fan speed while keeping the mixing ratio of gas (G) and air (A) of the gas/air mixture (M) at the defined mixing ratio thereby decreasing the opening position of the electric or electronic gas flow modulator,
• keep the electric or electronic gas flow modulator at said decreased opening position and terminate the actual burner-on-phase of the gas burner appliance.