Method for the failsafe and lean ignition of a gas-air mixture on a gas burner

A method for a failsafe and lean ignition of a fuel gas-air mixture on a gas burner, which is mixed in a mixing device arranged upstream of the gas burner using a fuel gas flowing in along a fuel gas flow path and air flowing in along an air flow path, a control valve provided along the fuel gas flow path comprises an actuator and a throttle element that can be moved by the actuator for a closed-loop control of a flow rate of the fuel gas flowing into the mixing device, the method comprising:

• moving the actuator into an actuator reference position;
• bringing the throttle element into a throttle reference position;
• performing a test to determine whether the throttle element is in the throttle reference position when the actuator is in the actuator reference position;
• moving the throttle element by the actuator in a flow rate-increasing manner starting at a start time (tD) from the throttle reference position;
• activating an ignition device for the ignition of the fuel gas-air mixture on the gas burner;
• and
• stopping the flow rate-increasing movement of the throttle element as soon as at least one of the following termination conditions occurs:
• the actuator reaches a predetermined limit position (sA);
• a differential pressure sensor for the acquisition of a pressure difference, referred to as offset pressure, between a measuring site along the fuel gas flow path and a measuring site along the air flow path acquires a predetermined limit pressure (pA);
• an ignition sensor for detecting an ignition of the fuel gas-air mixture detects an ignition of the fuel gas-air mixture.