A series of metallic heating elements of large sizes are presented. A conventional metallic tubular heating element is positioned into a hollow metallic profile, wherein additional high temperature resistant components are used in different assemblies, as required. A coiled resistance conductor is positioned within the interstice of two metallic tubes fitted into one another, wherein an electrically insulating powder or grit is used within the interstice, and to embed the coiled resistance conductor, and wherein additional high temperature resistant components are used in different assemblies, as required. The assemblies provide methods to reduce the use of electrically insulating powders and/or thermally conductive powders for large size heating elements, and more particularly for radiant purposes; and components are also presented to improve the emissivity of the outer surface of the radiant heating elements with a colorful look, for surface temperatures operating around and up to 500° C. to 600° C.