Abstract: A blower burner capable of operating in two burner steps comprises a drive for an air throttle capable of running in a first direction from closed to open and in a second direction from open to closed, an auxiliary switch connected to the drive of the air throttle, a latch-free no-voltage relay, and a single-wire relay. The auxiliary switch is activated by the drive when the drive is running towards open position before the air throttle reaches the set position for the first burner step. The no-voltage relay is excited upon activation by the auxiliary switch. The single-wire relay operates under the control of the latch-free, no-voltage relay to cause the drive to switch over to drive towards the closed position after a built-in delay when the no-voltage relay has been excited.