Abstract: A furnace having improved heat exchanger, which is particularly suitable for use in a positive pressure, direct-vented hot air furnace. The heat exchanger has a split housing construction allowing the heat exchanger to be partible into halves. Parting the heat exchanger housing of the present invention permits access to the ceramic combustion chamber disposed therein, facilitating periodic repair and replacement. The partible portions of the present heat exchanger housing are connectable using one of several available connection means, including bolted mating flanges, encircling clamps, and twisting quick-locking means. The connection between the partible portions is gasketed to provide a positive pressure seal of the connection, impeding leakage of pressurized combustion gases from within the heat exchanger to the occupied air.