Abstract: A combination burner for selectively firing oil, natural gas and liquid propane. A modular first section has primary and secondary air tubes coaxially arranged therein and communicates with the main combustion air supply fan. A modular section is joined by bolts or the like to the first section and into which the primary and secondary air tubes extend. A center air spin vane rack is upstream of the secondary air tube in the first section. An adjustable spin vane rack is located radially outwardly of the secondary air tube for selectively spinning the main combustion air for flame adjustability. An air diverter is provided at a downstream end of the primary air tube. A compressed air atomizer is also at the downstream end of the primary air tube.