Control method for the switching on operating sequence of a heating device using fuel, said switching on operating sequence comprising the following time periods: - a start-up phase (VPh) beginning with the start of the heating device, during which start-up phase (VPh) no fuel but only outside air being conveyed by a fan is supplied to the burner chamber for flushing, said start-up phase being terminated after a predeterminable period of time, - a starting time of the combustion, at which takes place the activation of the fuel supply and the ignition of the fuel-air mixture subsequently flowing into the burner chamber, - a steady-state continuous operating phase, during which the burner chamber is supplied with an air mass having a value m Lnormal required for achieving the desired lambda value and with a corresponding quantity of fuel, - a transition phase (ÜPh) preceding the steady-state continuous operating phase, which transition phase has a predeterminable time length and during which a reduced air mass is supplied to the burner chamber, said reduced air mass having a value m LÜbergang which is smaller than the value m Lnormal of the air mass being supplied to the burner chamber during the steady-state continuous operating phase, characterized, - in that the start-up phase (VPh) is terminated by the starting time of the combustion, - in that the transition phase (ÜPh) directly follows the starting time of the combustion, - in that the value m LÜbergang of the reduced air mass which is supplied to the burner chamber is maintained during a defined period of time which at least partially lies within the transition phase (ÜPh), and - in that the value m LÜbergang of this reduced air mass then rapidly increases to the value m Lnormal of the steady-state continuous operating phase. - a start-up phase (VPh) beginning with the start of the heating device, during which start-up phase (VPh) no fuel but only outside air being conveyed by a fan is supplied to the burner chamber for flushing, said start-up phase being terminated after a predeterminable period of time, - a starting time of the combustion, at which takes place the activation of the fuel supply and the ignition of the fuel-air mixture subsequently flowing into the burner chamber, - a steady-state continuous operating phase, during which the burner chamber is supplied with an air mass having a value m Lnormal required for achieving the desired lambda value and with a corresponding quantity of fuel, - a transition phase (ÜPh) preceding the steady-state continuous operating phase, which transition phase has a predeterminable time length and during which a reduced air mass is supplied to the burner chamber, said reduced air mass having a value m LÜbergang which is smaller than the value m Lnormal of the air mass being supplied to the burner chamber during the steady-state continuous operating phase, - in that the start-up phase (VPh) is terminated by the starting time of the combustion, - in that the transition phase (ÜPh) directly follows the starting time of the combustion, - in that the value m LÜbergang of the reduced air mass which is supplied to the burner chamber is maintained during a defined period of time which at least partially lies within the transition phase (ÜPh), and - in that the value m LÜbergang of this reduced air mass then rapidly increases to the value m Lnormal of the steady-state continuous operating phase.