Abstract: An apparatus for heating a process chamber. The apparatus includes a furnace structure that defines a reaction zone that communicates with the process chamber. A burner structure defines a burner port and communicates with the reaction zone through the burner port. The burner structure includes a plurality of mixer tubes. The mixer tubes mix fuel and oxidant and define flow paths for the fuel and oxidant. Each of the flow paths extends through a respective mixer tube. A valve assembly interrupts a flow of fuel and oxidant along one of the flow paths. The valve assembly is shiftable between a closed condition interrupting a flow of fuel and oxidant along the flow path, and an open condition not interrupting the flow. A controller operates to shift the valve assembly into or out of its open condition. The controller has a mode of operation including consecutive cycles in which the valve assembly is shifted into and out of its open condition.

Abstract: A premix burner apparatus includes a burner structure and a firing rate control system. The burner structure defines a premix reaction zone configured to communicate with a process chamber. The burner structure further defines a plurality of separate entrances to the reaction zone, and a corresponding plurality of separate premix flow paths, each of which is configured to direct both oxidant and fuel to a respective one of the entrances to the reaction zone. The firing rate control system is operative to control flows of oxidant and fuel along at least one of the flow paths separately from flows of oxidant and fuel along at least one other flow path.