PURPOSE: To improve the heat transmission effect and working efficiency by installing pipes for bath water heating and hot water heating, wound spirally in both pipes tightly adhered state to form a combustion heating chamber cylinder part.

CONSTITUTION: Heat resisting and heat transferring heating pipes 1 and 2 for both water heating and supply heating are wound spirally in both pipes tightly adhered state to constitute a heating annular cylinder 3. The pipes 1 and 2 are vertically over lapped or another across flame and smoke passing heating gaps 41 and 42 and aet at a heating furnace 5 to thereby form a combustion heating chamber cylinder part 6 at the core part. Further, the upper end opening 7 of a heat pipe 1 for heating bath water is communicated with a bathtub by way of a communication pipe 10 and an upper heat circulating pipe 9 and further the lower end opening (not shown) is communicated with the lower part of the bathtub 8 through a bath water forcibly circulating pump 12. Further, the upper end opening 15 of the heat pipe 2 for heating supply hot water is communicated with a hot water supply hot waternis communicated with a hot water supply exhaust pipe through a communication pipe 17 and the lower end opening with a supply source.