Boiler having increased indoor heating efficiency and enabling simultaneous use of indoor heating and hot water

A boiler having enhanced heating efficiency and enabling simultaneous use of heating and hot water, the boiler including a tank (110) having a space provided therein for storing heating-water, a main heat exchanger (130) for heating heating-water using combustion heat of a burner (140) and a hot-water heat exchanger (180) for heating cold water into hot water through a heat exchange between heating-water heated in the main heat exchanger (130) and the cold water, comprising;

• an internal heating-water piping line (160) composed of a first heating-water connecting pipe (160a) through which heating-water in the tank (110) is supplied to the main heat exchanger (130) and a second heating-water connecting pipe (160b) through which heating-water passed through the main heat exchanger (130) is supplied to the tank (110), thereby forming a heating-water circulation flow path for heating-water forcibly fed by an internal circulation pump (120) between the tank (110) and the main heat exchanger (130);
• a heating-water supply piping line (210) composed of a heating-water supply pipe (210a) for supplying heating-water in the tank (110) to heating equipment (230) and a heating-water return pipe (210b) for returning heating-water passed through the heating equipment (230) to the tank (110), thereby forming a heating-water circulation flow path for supplying and returning heating-water forcibly fed by an external circulation pump (220) between the tank (110) and the heating equipment (230);
• and
• a three way valve (170) provided on the second heating-water connecting pipe (160b), an opening rate thereof being adjusted depending on a heating load and hot water load to supply heating-water passed through the main heat exchanger (130) toward the tank (110) and the hot water exchanger (180),
• wherein the boiler internal water piping line (160) and the heating-water supply piping line (210) are connected to each other via the space in the tank (110).