Heat exchanger and water heater

A heat exchanger configured to heat a fluid by heat exchange with combustion exhaust gas ejected from a burner, the heat exchanger comprising:

• a case body;
• a plurality of heat-transfer tubes arranged in at least a vertical direction inside the case body;
• a header configured to communicate open ends of the plurality of heat-transfer tubes arranged in the vertical direction, the header being provided in a side wall outer surface of the case body, and having a header body to which the open ends of the plurality of heat-transfer tubes are connected, and a header cover joined to the header body;
• a drainage member disposed at at least one of the open ends protruding into an internal space of the header, the drainage member having a flow guide portion including an insertion portion configured to be inserted into the heat-transfer tube from the open end, and a projecting portion provided continuously to the insertion portion so as to project toward an outside of the heat-transfer tube from the open end, and further extend downward;
• and
• a flow guide space configured to guide the fluid inside the heat-transfer tube to the outside of the heat-transfer tube, when the insertion portion is inserted into the heat-transfer tube from the open end, the flow guide space being formed continuously between the insertion portion and a lower inner wall of the heat-transfer tube, and between the projecting portion and the open end of the heat-transfer tube.