leekahi, milles metalli kuumutus või sulatus toimub kütuse gaasiliste põlemisproduktide ja ahju seintelt lähtuva soojuskiirguse toimel (vt leekahi; vrd kaudtoimeleekahi), a furnace in which the flame used for heating or melting the metal does not impinge on the metal surface itself, but is reflected off the walls of the root of the furnace; the metal is actually heated by the generation of heat from the walls and the roof of the furnace (see: fired furnace; compare: indirect fuel-fired furnace)