| 摘要 |
PURPOSE:To prevent a corrosion of a heat exchanger caused by an occurrence of drain by a method wherein an air feeding device for mixing air into a space around a part where a heat exchanger always produces a drain. CONSTITUTION:An air feeding device 10 is arranged at a combustion casing 1 and this air feeding device is constituted by several through-holes 11 communicating with an interior or an exterior of the combustion casing and a fan 13 for feeding air into a covering pipe 12 covering all the through-holes from an external surface of the combustion casing 1. Air fed into the covering pipe 12 under an operation of the fan 13 is blown into a space between a water feeding part 3a and a hot water feeding part 3b of a heat exchanger 3 within the combustion casing 1 through several through-holes 11 and the air is mixed into a spacing 9 around a part where a drain is easily made, in particular a space 9 around the hot water feeding-out part 3b. With this arrangement, water content in the space 9 is made thin and a vapor pressure is made to a value lower than a saturation vapor pressure, so that no drain is formed in the heat exchanger. |
