A method and apparatus that applies corrections to the mass flow rate of combustion air into a gas or oil-fired, forced-draft burner, and thus provides for correcting the air-fuel ratio, by directly measuring the combustion air temperature and/or the barometric pressure of the combustion air, and using these measurements to develop a fan speed drive signal that corrects the volume of air inlet to the burner system without the use of the complex and expensive fully metered control systems, or elaborate feedback systems, or systems that require real-time combustion analysis, and the like.