Abstract: Spread of leaking combustion exhaust or the like is suppressed and a thermal fuse is made to operate in definitive fashion. A back flange is made to protrude so as to be directed toward a rear wall of an outer casing from a joint between a combustor casing and a heat exchanger casing to a location in the vicinity of the rear wall. A thermal fuse is arranged about the periphery of the heat exchanger casing so as to extend along a region near a protruding end edge of the back flange. The back flange is provided with a through hole, and combustion exhaust which leaks from the combustor casing is guided to the thermal fuse. A back flange which is similar thereto is installed at an upper location so as to straddle a tubing elbow. The two flanges are made to protrude beyond the tubing elbow.

Abstract: Spread of leaking combustion exhaust or the like is suppressed and a thermal fuse is made to operate in definitive fashion. A back flange is made to protrude so as to be directed toward a rear wall of an outer casing from a joint between a combustor casing and a heat exchanger casing to a location in the vicinity of the rear wall. A thermal fuse is arranged about the periphery of the heat exchanger casing so as to extend along a region near a protruding end edge of the back flange. The back flange is provided with a through hole, and combustion exhaust which leaks from the combustor casing is guided to the thermal fuse. A back flange which is similar thereto is installed at an upper location so as to straddle a tubing elbow. The two flanges are made to protrude beyond the tubing elbow.