Abstract: A furnace having sidewalls to form an enclosure to contain a melt. One or more burners are positioned to fire into the enclosure to maintain the melt and one or more charge wells are separated from the enclosure by the sidewalls. A charge of material to be melted is loaded into the charge wells and melted. Submerged openings defined in the sidewall circulate melt to the charge well(s) and to circulate the melt back to the enclosure. Submerged pumps effectuate the circulation. Flue gas openings defined in the sidewall(s) are configured to direct flue gas into the charge well(s) and on to said the charge of material. Two opposed charge wells and pumps may be provided as wells as flue gas openings to heat the charge of material deposited into the charge wells. The flue gas openings allow flue gas to impinge onto the charge of material to be melted so that heat that would otherwise be lost in the flue gas is used to help melt the charge of material.