Patent ID: 8783213

Claim:
A heat exchanger comprising: a heat transfer tube for heat exchange, the heat transfer tube being a spiral tube shaped oval in plan view and being constituted with a plurality of loop portions which are continuous with each other and vertically stacked on each other; a case having a plurality of wall portions surrounding the heat transfer tube and formed with an intake vent and an exhaust vent for taking in and exhausting heating gas, the plurality of wall portions including a first wall portion formed with the intake vent so as to communicate with space regions surrounded with the plurality of loop portions of the heat transfer tube, a second wall portion opposed to the first wall portion across the heat transfer tube and defining a first gap between the second wall portion and the heat transfer tube, and a third wall portion interconnecting the first and second wall portions, the case defining therein a first space region which is located closer to the third wall portion than a region formed with the intake vent and which accommodates therein at least part of the heat transfer tube, and a second space region which is located on a side opposed to the first space region across the region formed with the intake vent and which is in communication with the exhaust vent; and a guide member having a main body located closer to the second space region than the intake vent, the upper portion of the main body being located directly above the intake vent, wherein the guide member guides heating gas entering the case through the intake vent so as to be inhibited from directly proceeding into the second space region by the main body and to proceed toward the first space region, thereby the proceeding direction of the heating gas is reversed and the heating gas proceeds toward the second space region, the upper portion of the guide member, together with the second wall portion, defining therebetween a second gap in communication with the first gap for allowing part of the heating gas having been guided to the first space region to proceed into the second space region through the first and second gaps.