Low pressure drop, low NO_x, induced draft gas heaters

摘要

An improved induced draft gas burner assembly for low NO_x residential and light commercial gas furnaces is disclosed. The improved burner includes an upstream assembly coupled to a fuel inlet and an air inlet. The air inlet is coupled to a neck extending between the air inlet and the outlet of the neck, both of which may be disposed within an optional chamber. If used, such a chamber also includes an outlet coupled to a burner. In practice, the chamber and neck behave as a Helmholtz resonator that can be tuned to provide an upstream impedance Z_up that exceeds the downstream impedance Z_down of the components downstream of the burner assembly.