A bottom heated holder furnace (10) for containing a supply of molten metal includes a storage vessel (20) having sidewalls (22) and a bottom wall (24) defining a molten metal receiving chamber (26). A furnace insulating layer (32) lines the molten metal receiving chamber (26). A thermally conductive heat exchanger block (50) is located at the bottom of the molten metal receiving chamber (26) for heating the supply of molten metal. The heat exchanger block (50) includes a bottom face (55), side faces (56), and a top face (57). The heat exchanger block (50) includes a plurality of electrical heaters (70) extending therein and projecting outward from at least one of the faces of the heat exchanger block (50), and further extending through the furnace insulating layer (32) and one of the sidewalls (22) of the storage vessel (20) for connection to a source of electrical power. A sealing layer (60) covers the bottom face (55) and side faces (56) of the heat exchanger block (50) such that the heat exchanger block (50) is substantially separated from contact with the furnace insulating layer (32). A gas pressurization valve (118) is in fluid communication with the molten metal receiving chamber (26) and the interior of the heat exchanger block (50) for pressurizing the interior of the holder furnace (10).
