A method of manufacturing mineral fibers includes rotating an orificed spinner and supplying molten mineral material to the spinner to centrifuge steams of molten mineral material. A downward annular flow of attenuating gases is directed to attenuate the streams of molten mineral material into mineral fibers. A mixture of combustion air and combustion gas is supplied to an annular burner positioned around the spinner. Heat from the annular burner is directed toward the spinner and the streams of molten mineral material to heat the spinner and assist in attenuating the streams of molten mineral material into mineral fibers. A pressure sensor senses the pressure of the combustion air prior to the introduction of the combustion air to the burner. The pressure of the combustion air is controlled in response to the sensed pressure to maintain the pressure of the combustion air at a specific pressure.