Heat exchanger

A heat exchanger comprising:

• a burner configured to burn a mixture of air and fuel;
• and
• a heat exchange unit configured to exchange heat between combustion gas generated by combustion of the burner and a heating medium,
• wherein the heat exchange unit is formed by a plurality of stacked unit plates,
• wherein the heat exchange unit comprises a sensible-heat exchange unit and a latent-heat exchange unit, the sensible-heat exchange unit and the latent-heat exchange unit being integrally formed by the plurality of stacked unit plates and arranged around a periphery of the burner in a coaxial structure such that the sensible-heat exchange unit is part of the stacked unit plates and is located at an inner region of each of the plurality of stacked unit plates, and the latent-heat exchange unit is part of the stacked unit plates and is integrally formed with the sensible-heat exchange unit at an outer region of each of the plurality of stacked unit plates,
• wherein a first heating medium passage and a first combustion gas passage are separately and alternately formed adjacent to each other through the entirety of the stacked unit plates of the sensible-heat exchange unit, a second heating medium passage and a second combustion gas passage are separately and alternately formed adjacent to each other through the entirety of the stacked unit plates of the latent-heat exchange unit, and a combustion gas discharge passage is formed at an edge of each of the plurality of unit plates to discharge combustion gas that has passed through the first combustion gas passage and the second combustion gas passage,
• wherein, in the plurality of stacked unit plates, a flow direction of the heating medium passing through the first heating medium passage of a first unit plate of the plurality of stacked unit plates and a flow direction of the heating medium passing through the first heating medium passage of a second unit plate adjacent to the first unit plate of the plurality of stacked unit plates are opposite to each other, and
• wherein each respective flow direction extends entirely from an inlet to an outlet of the respective heating medium passage.