Hot-water supply system having dual pipe

A hot water supplying apparatus comprising:

• 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 from the burner, and a plurality of inner pipes formed in the outer pipe, where the inner pipes are connected to the water inlet pipe, for allowing the cold water, which is introduced through the water inlet pipe, to be heated while passing through the plurality of inner pipes;
• and
• a water outlet pipe for discharging the heated water from the heat exchanging pipe, wherein the plurality of inner pipes are arranged in parallel, and inserted into the outer pipe, wherein the plurality of inner pipes are inserted to a desired depth into the outer pipe, while the cold water introduced into the plurality of inner pipes are blocked by a sidewall of the outer pipe so as to flow in an opposite direction to the introduced direction.