A method of assembling multiple low NOx burners including the step of assembling multiple bodies, each body including a multiple first burner ports connected to a first burner inlet and multiple second burner ports connected to a second burner inlet. The method also including the step of selecting one of the bodies and inserting a first inlet tube into the second burner inlet to provide a fuel/air mixture to the second burner ports at a first rate. The method also including the step of selecting one of the bodies and inserting a second inlet tube into the second burner inlet to provide the fuel/air mixture to the second burner ports at a second rate different than the first rate.