For all firing processes, the energy supplied by the burners must match the requirements at any given moment so that the required temperature can be achieved for the process. The capacity changes dependent on the furnace chamber and material temperature parameters. The continuous signal from the temperature controller is converted into a pulse/pause signal (frequency modulation) for each burner by the impulse system. For heating/cooling mode the impulse system supplies one output signal per burner and also one output signal per heating/cooling zone.

The impulse system ensures uniform temperature distribution in the furnace by operating the burners cyclically.

The air control valve is actuated when capacity is required. This results in an increase in the air pressure on the burner. The air/gas ratio control regulates the gas pressure proportionate to the air pressure so that the gas/air mixture always remains at a constant ratio. For impulse control, the burners are operated at two capacity points: low-fire and rated capacity (Low/High) or off and rated capacity (Off/High). In Off/High mode the burner is started at ignition capacity before switching to rated capacity.

The low-fire and rated capacity operating points are defined by the end positions of the air control valve.