Patent ID: 7819656

Claim:
A method of operating a heater including a radiant heating zone comprising a lower portion including a hearth burner section and an upper portion including a wall burner section; at least one tubular heating coil located in the radiant heating zone, the heating coil having a length; the hearth burner section comprising a plurality of hearth burners located adjacent to the bottom hearth for firing in the radiant heating zone; and the wall burner section comprising a plurality of wall burners located adjacent to opposing walls, the method comprising: introducing to the wall burner section a first air and fuel mixture having less than the stoichiometric quantity of air for combustion of fuel introduced to the wall burner section, and introducing to the hearth burner section a second air and fuel mixture having greater than the stoichiometric quantity of air for combustion of fuel introduced to the hearth burner section, the overall quantity of air introduced to the hearth burner section and wall burner section being at least a stoichiometric quantity.