Patent ID: 8167610

Claim:
A furnace for heating an occupied space while producing lower than standard NOx emissions, the furnace comprising: an air inlet passage comprising an inlet tube having an inlet end; a fuel injector mounted at the inlet end of the inlet tube, the fuel injector comprising an orifice that dispenses the fuel, wherein the fuel injector is oriented so that the fuel injector dispenses the fuel into the inlet end of the inlet tube, and wherein space between the fuel injector and the inlet tube permits air to enter the inlet tube around the fuel injector; a mixing device downstream of the fuel injector that mixes the air and fuel prior to combustion, wherein the mixing device is in addition to the inlet tube, the mixing device is located inside the inlet tube, and the mixing device is attached to the fuel injector; a burner plate downstream of the mixing device separating unburned air and fuel mixture on an upstream side of the burner plate from burning air and fuel and products of combustion on a downstream side of the burner plate, the burner plate comprising multiple ports therethrough that the air and fuel mixture pass through; a combustion chamber downstream of the burner plate and defined on an upstream side by the burner plate; multiple parallel heat exchanger tubes downstream of the combustion chamber that transfer heat from the products of combustion to air to be delivered to the occupied space; and a fan downstream of the heat exchanger tubes that draws air through the air inlet passage, mixing device, burner plate and combustion chamber, and that draws products of combustion through the heat exchanger tubes.