Gas furnace to produce heated air and optionally hot water via a bypass pipe

A gas furnace including a primary heat exchanger and a secondary heat exchanger through which a combustion gas produced by the combustion of a fuel gas flows, the gas furnace comprising:

• a coupling box connecting the primary heat exchanger and the secondary heat exchanger;
• a collect box connected to the secondary heat exchanger and into which the combustion gas passed through the secondary heat exchanger is introduced;
• an inducer connected to the collect box and causing a flow of the combustion gas;
• and
• a bypass pipe connected to one side of the coupling box and guiding the combustion gas passed through the primary heat exchanger to a hot water supply tank,
• wherein the primary heat exchanger communicates with the secondary heat exchanger or the bypass pipe through the coupling box,
• wherein the coupling box has an opening facing the primary heat exchanger and secondary heat exchanger, and comprises a partition wall disposed at a corresponding position between the primary heat exchanger and the secondary heat exchanger,
• wherein the partition wall divides the coupling box into a first box and a second box which communicate with the primary heat exchanger and secondary heat exchanger, respectively.