a system for supplying molten thermoplastic material to a dispenser through a supply hose comprises a hopper for storing the thermoplastic material . a heating grid associated with the hopper heats and melts the thermoplastic material . a reservoir block receives the melted material from the grid . the reservoir block includes a reservoir into which the melted material flows from the grid . a manifold assembly is supported below the reservoir block for receiving material from the reservoir . the manifold assembly includes a fitting for connection to the supply hose , a pump for pumping the material through the supply hose to the dispenser , a passageway system connecting the pump to the fitting for supplying a flow of material from the pump to the fitting , a filter connected to the passageway system for filtering impurities in the material after the material has been pumped , and a valving arrangement connected to the passageway system and separate from the filter which selectively directs a flow of the material in the passageway system through the filter to backflush the filter . the filter and the valving arrangement permit the filter to be removed without dislodging the contaminants in the filter . the backflushing capability allows the filter to be cleaned periodically without removal of the filter and without changing the position of the filter . when the filter is backflushed , the material flows through a drain valve assembly which opens automatically in response to pressure of the material from the pump .