A furnace system including an outer shell which comprises a top flange, an elongated body portion, and a bottom flange, wherein the outer shell is a pressure vessel, with no penetrations in the elongated body portion; a heater assembly which comprises (i) a single-piece annular shaped insulation layer, and (ii) a plurality of heaters embedded in the insulation layer, wherein the heater assembly is disposed within the elongated body portion of the outer shell; and an innermost layer disposed within the annular-shaped insulation layer, wherein the innermost layer is a baffle tube configured to force a natural convective flow, wherein each of the plurality of heaters is individually controllable and the plurality of heaters are configured to heat different zones within the furnace to different temperatures and/or at different rates. The system may be used to heat treat magnet materials, such as those formed of Bi-2212, therein.