| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent deformation at the bottom part of a liquid tank by forming it of a stainless material, bonding a passage forming member to the rear surface of the stainless material in face contact state and forming a combustion gas passage on the rear side at the bottom part of the liquid tank. SOLUTION: A bottom plate unit 6 is provided with a stainless plate 7 of substantially same size as the bottom part 4b of a liquid tank 4 and a plurality of copper passage forming members, i.e., rectangular pipes 8, are bonded to the rear surface of the stainless plate 7 in face contact state. The stainless plate 7 has a coefficient of linear expansion substantially identical to that of pure copper and the rectangular pipe 8 is formed of pure copper. Side wall part 8a on the upper surface side is bonded continuously by brazing the rear surface in a furnace except the front part 7a of the stainless plate 7 and the hole of the rectangular pipe 8 provides a combustion gas passage 9. This structure prevent deformation at the bottom part 4b of the liquid tank 4.</p> |
