| 摘要 |
PROBLEM TO BE SOLVED: To provide a low cost gas water supply heater in which any scale is prevented from being produced owing to deposition of a very small amount of ammonium sulfate and corrosion of a constituent material in wetting, and it is operable over a long period of time without causing deterioration of heat transfer property. SOLUTION: In a gas water supply heater 7 where heat of waste gas is recovered, parts of a heat transfer tube and fins where waste gas temperature is 200 deg.C or lower are formed with a ferrite iron base material containing Cr of 9% or more. As the ferrite iron base material there is used any of STBA26, STBA27, STBA28, SUS410, SUS405, SUS410L or SUS430 in JIS standard. Herein, the fin may be preferably constructed with a ferrite iron base material containing Cr of 13% or more such as SUS410L.
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