Heat exchanger, water heater and water tube

Abstract

A water tube WT of a heat exchanger B includes a helical tube body 5 which includes a plurality of loops 50 arranged in the axial direction. At least one of the loops 50 includes an inclined tube portion which is inclined with respect to the axial direction and a non-inclined tube portion extending perpendicularly to the axial direction. The inclined tube portion is provided at each of opposite end regions s 2 a and s 2 b in a width direction crossing the axial direction, whereas the non-inclined tube portion is provided at an intermediate region S 1 in the width direction. With this structure, the pitch p 2 of the loops 50 is reduced. Therefore, by increasing the number of loops 50, high heat exchange efficiency is achieved without considerably increasing the size of the helical tube body 5.

1 . A heat exchanger comprising: a casing into which combustion gas is to be introduced; and
 a water tube for recovering heat from the combustion gas, the water tube being accommodated in the casing and including a helical tube body which includes a plurality of loops arranged in an axial direction and continuously connected to each other;   wherein at least one of the loops includes an inclined tube portion which is inclined with respect to the axial direction and a non-inclined tube portion extending perpendicularly to the axial direction, the inclined tube portion being provided at each of opposite end regions in a width direction crossing the axial direction, whereas the non-inclined tube portion being provided at an intermediate region in the width direction.   
   
   
       2 . The heat exchanger according to  claim 1 , wherein all of the loops include the inclined tube portion and the non-inclined tube portion. 
   
   
       3 . The heat exchanger according to  claim 1 , wherein each of the loops includes a pair of straight tube portions extending in the width direction and substantially in parallel with each other, and a pair of bent tube portions connected to ends of the straight tube portions;
 wherein each of the straight tube portions is the non-inclined tube portion, whereas each of the bent tube portions is the inclined tube portion.   
   
   
       4 . The heat exchanger according to  claim 1 , wherein the helical tube body is so disposed in the casing that the loops are arranged vertically;
 wherein the casing includes a pair of walls sandwiching the helical tube body in a horizontal direction, the paired walls being formed with a gas supply port and a gas discharge port, respectively; and   wherein combustion gas introduced into the casing through the gas supply port flows through a gap between adjacent ones of the loops and is discharged from the casing through the gas discharge port.   
   
   
       5 . The heat exchanger according to  claim 4 , wherein the water tube includes an extension connected to a lower end of the helical tube body; and
 wherein part of the extension is positioned outside the casing, and said part is provided with a bent portion which is so bent as to reduce a height thereof as extending toward an end of the extension.   
   
   
       6 . A water heater comprising a burner and a heat exchanger, the heat exchanger comprising:
 a casing into which combustion gas is to be introduced; and   a water tube for recovering heat from the combustion gas, the water tube being accommodated in the casing and including a helical tube body which includes a plurality of loops arranged in an axial direction and continuously connected to each other;   wherein at least one of the loops includes an inclined tube portion which is inclined with respect to the axial direction and a non-inclined tube portion extending perpendicularly to the axial direction, the inclined tube portion being provided at each of opposite end regions in a width direction crossing the axial direction, whereas the non-inclined tube portion being provided at an intermediate region in the width direction.   
   
   
       7 . A water tube for a heat exchanger, the water tube comprising a helical tube body which includes a plurality of loops arranged in an axial direction and continuously connected to each other;
 wherein at least one of the loops includes an inclined tube portion which is inclined with respect to the axial direction and a non-inclined tube portion extending perpendicularly to the axial direction, the inclined tube portion being provided at each of opposite end regions in a width direction crossing the axial direction, whereas the non-inclined tube portion being provided at an intermediate region in the width direction.