A wood burning furnace providing, in sequential connection, an air box, a fire box with a wood storage box/primary combustion chamber and a secondary combustion chamber separated by an ash grate, a heat exchanger, an exhaust manifold, and a smoke stack. The air box has an input port attached to an intake air blower. The air box also has two dampers, a thermostatically controlled first damper providing controlled access to an updraft exhaust pipe connected to the smoke stack. The second damper provides controlled access to the wood storage box/primary combustion chamber.