Heat exchanger and water heater

摘要

A heat exchanger A 1 includes a coiled tube 60 including a plurality of loops 60 a, and a space 35 surrounded by the coiled tube 60 and having an end closed by a partition 19. The heat exchanger is so designed that combustion gas flows from the space 35 to a combustion gas path 36 by passing through clearances 61 of the loops 60 a of the coiled tube 60. The loops 60 a are made of a tube having a thickness t 1 and a width L 1 which is larger than the thickness, so that the amount of heat recovery when the combustion gas passes through the clearances 61 is large. Therefore, the heat exchange efficiency is enhanced while simplifying the overall structure of the heat exchanger A 1 and reducing the size of the heat exchanger.