Method and apparatus for mitigating premix burner combustion tone

A method of calibrating a furnace, comprising:

• determining a first flame stabilization period for a furnace that avoids detachment of a flame from a burner within a burner box of the furnace;
• determining a second flame stabilization period that is longer than the first flame stabilization period and avoids emission of a combustion tone;
• and
• configuring a controller of the same or another furnace to utilize a third flame stabilization period that has a duration between the first and second flame stabilization periods;
• wherein each flame stabilization period commences upon ignition of a premixed mixture of air and fuel at the burner while an inducer fan that is in fluid communication with the burner box operates within a first range of fan speeds, and terminates when the rotational speed of the inducer fan increases to a second range of fan speeds that is greater than the entire first range;
• and
• wherein the method includes cycling the furnace OFF and ON in each of a plurality of iterations, each iteration using a different respective one of a plurality of flame stabilization periods, as part of said determining a first flame stabilization period and said second flame stabilization period.

A furnace comprising:

• a heat exchanger;
• a burner assembly in thermal communication with the heat exchanger, the burner assembly including a mixing tube that provides a premixed mixture of air and fuel to a burner in a burner box;
• an inducer fan operable to extract combustion gases from the burner;
• and
• a controller operable to:
• determine a first flame stabilization period for a furnace that avoids detachment of a flame from the burner;
• determine a second flame stabilization period that is longer than the first flame stabilization period and avoids emission of a combustion tone;
• and
• cycle the furnace OFF and ON in each of a plurality of iterations, each iteration using a different respective one of a plurality of flame stabilization periods, as part of the determination of the first flame stabilization period and the second flame stabilization period;
• and
• utilize a third flame stabilization period that has a duration between the first and second flame stabilization periods;
• wherein each flame stabilization period commences upon ignition of a premixed mixture of air and fuel at the burner while an inducer fan that is in fluid communication with the burner box operates within a first range of fan speeds, and terminates when the rotational speed of the inducer fan increases to a second range of fan speeds that is greater than the entire first range.