A method to adjust a boiler having a flue gas duct including: sensing flue gas emissions in the gas duct with a plurality of emission sensors arranged in an array; generating a multidimensional graphical depiction of the flue gas emissions by plotting sensor data captured from the emission sensor; adjusting the boiler to modify the distribution of flue gases in the gas duct; generating a subsequent multidimensional graphical depiction of the flue gas emissions by plotting sensor data captured subsequent to the boiler adjustment, and repeating these steps until the graphical depiction displays an acceptable plot of flue gas emissions.