A method and/or apparatus for efficiently operating a combustion device including at least one control zone, with each control zone including at least one burner assembly, is disclosed and includes a) individually supplying fuel to each of the burner assemblies in each of the control zones, b) individually measuring a separate combustion characteristic of the collective combusted gas from each of the burner assemblies in each of the control zones, and c) individually adjusting the flow of air to each of the burner assemblies in response to the value of the combustion characteristic corresponding to each of the control zones to keep the value of each separate combustion characteristic within a predetermined range. In a preferred embodiment, primary air and secondary air are separately supplied and controlled to each of the burner assemblies in each of the control zones in response to the value of the combustion characteristic corresponding to each of the control zones.