Method and apparatus for heating glass sheets with recirculated gas

A furnace for heating a sheet of glass while supporting on a layer of gas comprising:

• an enclosure, means to heat said enclosure, a glass support bed within said enclosure having gas passages therethrough, an enclosed plenum chamber in communication with said gas passages, means for pressurizing said plenum chamber including an air flow amplifier having a conduit-like configuration with an inlet throat at one end in communication with ambient gas in said enclosure and an outlet opening at the opposite end in communication with said plenum chamber, a compressed gas tube connected at one end to a side inlet of said air flow amplifier and at the other end to a source of compressed gas outside of said enclosure, and a narrow, peripherally extending opening adjacent to the inside surface of said inlet throat communicating with the compressed gas inlet and adapted to direct a high velocity stream of gas along the interior surface of said inlet throat, whereby ambient gases in said enclosure are drawn into said plenum and forced through said passages in said support bed with sufficient pressure to establish gas support for a sheet of glass overlying said bed.