Abstract: A metal preheating apparatus has a box-like structure including, a bottom, a top wall, a pair of sidewalls, and a pair of end walls forming an enclosed receptacle. Fluid channels are defined between the outer surfaces of a pair of inner walls spaced inwardly from the sidewalls and the inner surfaces of the sidewalls. The upper and lower edges of the inner walls terminate short of the top wall and short of the bottom to place the upper portion of the receptacle in fluid communication through the fluid channel with the lower portion of the receptacle. A horizontally, oriented, load supporting grate member is positioned intermediate these apertures and extends longitudinally between the end walls and transversely between the inner walls. The bottom of the structure is open. The top wall of the structure contains an upper door for charging scrap metal into the upper portion of the receptacle so that the scrap metal is supported by the grate member.