Patent ID: 7913683

Claim:
A heater assembly adapted for use with a radiant heating tube capable of burning a mixture of combustible gas and air, the heater assembly comprising: an air duct section forming a combustion air passage and having a central longitudinal axis, an inlet end for receiving combustion air, and an opposite outlet end for connection to said radiant heating tube, said passage extending between said inlet end and said outlet end; a blower having an air inlet and an air outlet and adapted to provide pressurized combustion air to said inlet end of the air duct section, said blower being sealingly connected to said air duct section at said inlet end; a burner assembly mounted in said air duct section and including a burner nozzle adapted for connection to a combustible gas supply unit and a burner head for mixing said combustible gas and combustion air to form said mixture for burning in said heating tube, said burner head having an inlet portion with upstream and downstream ends and a substantially cylindrical outlet portion located at said downstream end of the inlet portion, the diameter of said outlet portion being greater than the transverse dimensions of said inlet portion measured perpendicular to said central longitudinal axis, said inlet and outlet portions being rigidly connected to each other by an annular disk having a plurality of perforations formed therein and extending radially between said downstream end of said inlet portion and an upstream end of the outlet portion, said perforations allowing combustion air to flow from the combustion air passage into said outlet portion during use of the heater assembly, said inlet portion having openings distributed around the periphery thereof for passage of combustion air into said burner head; a perforated, flow restricting plate mounted in said air duct section, extending circumferentially around said burner head and substantially spanning said combustion air passage between said burner head and said air duct section, said plate having an array of air holes distributed over the plate; and an igniter adapted for mounting adjacent said burner assembly for igniting said mixture of combustible gas and air, wherein said restricting plate in use allows a substantially laminar air flow downstream of the restricting plate around the circumference of the outlet portion of the burner head and increases flow of pressurized combustion air through said openings formed in the inlet portion of the burner head.