Abstract: An auxiliary heating means for improving the melting efficiency of melter kettles used to melt thermoplastic pavement marking materials. The auxiliary heating means includes a tube assembly through which thermoplastic material received from the bottom of the melter kettle is transferred to the top of the melter kettle. The tube assembly comprises an odd number of tubes having augers therein. The tube assembly is coupled to a side portion of the melter kettle and located within a heat chamber through which hot combustion gases from a combustion chamber at the bottom of the melter kettle flow and transfer heat into the tube assembly. The heat chamber comprises an extended portion of a heat chamber that surrounds the melter kettle.