Abstract: Disclosed is a heat exchanger for a condensing boiler supplying both heating water and hot water, which can use a double pipe as a sensible heat exchanger, instead of the use of an indirect heat exchanger. The heat exchanger includes: a sensible heat exchanger; and a latent heat exchanger made by connecting a plurality of unit heat exchangers to define exhaust gas pathway, each unit heat exchanger being manufactured in such a manner that three plates having a convexo-concave shape are stacked on one another to define a heating water pathway and a hot water pathway to be adjacent to each other in order to increase a heat transfer area.

Abstract: Disclosed is a hot water supplying apparatus having an auxiliary heat exchanger. The hot water supplying apparatus comprises: a heat exchanger including an inlet pipe for introducing heating water into the heat exchanger, and first, second, and third heat exchanging pipes connected to the inlet pipe and sequentially arranged; and an auxiliary heat exchanging device installed at an inlet port of the heat exchanger through which the heating water is introduced, the auxiliary heat exchanging device including a first auxiliary heat exchanging pipe connecting the inlet pipe to the first heat exchanging pipe, a second auxiliary heat exchanging pipe connecting the second heat exchanging pipe to the third heat exchanging pipe, and heat transfer fins for transferring heat energy from the second auxiliary heat exchanging pipe to the first auxiliary heat exchanging pipe.

Abstract: Disclosed is a hot water supplying apparatus which has a dual pipe capable of transferring heat energy of hot water, which is heated by heat of combustion of a burner and flows in pipe of a heat exchanger, to an inner pipe in which cold water is introduced, thereby inhibiting the condensation of moisture so as to prevent the corrosion of parts in the hot water supplying apparatus. The hot water supplying apparatus, comprises: a burner for supplying heat; a water inlet pipe for supplying cold water; a heat exchanging pipe formed with a dual pipe including an outer pipe for directly receiving combustion heat of the burner, and an inner pipe formed in the outer pipe, for allowing the cold water, which is introduced through the water inlet pipe, to be heated while passing through the inner pipe; and a water outlet pipe for discharging the heated water from the heat exchanging pipe.

Abstract: An arrangement structure of heat exchangers in a condensing gas boiler is provided, which includes a casing provided with a combustion chamber therein, and a gas burner provided in the lower portion of the combustion chamber.