A method includes firing a first burner into a furnace process chamber in a first initial condition, firing a second burner into the process chamber in a second initial condition, and measuring temperature at each of an array of locations in the process chamber. The first burner is adjusted to a first adjusted condition while the second burner is being fired at the second initial condition, and a resulting first temperature change is measured at each of the locations. The second burner is adjusted to a second adjusted condition while the first burner is being fired at the first initial condition, and a resulting second temperature change is measured at each of the locations. The measured first and second temperature changes are recorded as reference data for adjusting burner conditions to adjust temperatures at each of the locations. The method can thus be used to improve temperature uniformity throughout the array of locations.