Patent ID: 6772753
Filing Date: 2004-08-10
Classification: F24C,F26B

Abstract:
An oven heater for heating an oven containing volatile organic compounds, comprising: a gas-fired burner communicating with a heat exchanger receiving air from said oven and circulating heated air to said oven, said heat exchanger including an exhaust duct, a fixed annular orifice plate within said exhaust duct including an opening therethrough maintaining a predetermined minimum fluid pressure drop at a predetermined gas flow rate through said exhaust duct, a moveable orifice adjustment plate mounted adjacent said fixed annular orifice plate at an upstream side of said fixed annular orifice plate having an opening aligned with said opening through said fixed annular orifice plate, and an adjustment mechanism connected to said moveable orifice adjustment plate for moving said moveable orifice plate relative to said fixed orifice plate from a retracted position, wherein said opening of said moveable orifice adjustment plate is generally aligned with said opening through said fixed annular orifice plate, to an extended position restricting said opening through said fixed annular orifice plate to adjust an effective opening through said fixed and moveable orifice plates, thereby adjusting said pressure drop.