Abstract: An electrically energized aluminum melting furnace comprises a vessel for supporting molten aluminum and a roof and upper wall structure cooperating with side walls of the vessel to define a heating chamber above the molten aluminum. A plurality of unshielded resistance heating elements are supported by the roof and upper wall structure above the molten aluminum. The molten aluminum has access through a submerged opening to a charging well to which unmelted aluminum is periodically charged without danger that molten aluminum will splash upon the heating elements. Heat conducted from the heating chamber through the body of molten aluminum residing in the vessel is utilized to melt in the charging well the aluminum charged thereto. The melted aluminum in the charging well is permitted to flow through the heating chamber and through a submerged opening to a hot metal well from which hot metal may be withdrawn by any of numerous techniques.

Abstract: The invention is an improved detector system for determining and indicating the level of a molten charge within a furnace. The system can determine the level of the charge without the need for having contacts or other sensing devices within the furnace by sensing impedance changes in the furnace's heating coils.