Heat exchanger and hot water apparatus including heat exchanger

A heat exchanger comprising:

• a case into which a combustion gas is supplied;
• a plurality of heat transfer tubes that are accommodated in the case and have end parts drawn out to outside of the case via a plurality of hole parts provided at a sidewall part of the case;
• and
• a header part that is arranged on an outer surface side of the sidewall part, wherein the header part has:
• a plurality of hole parts through which the end parts of the plurality of heat transfer tubes are inserted;
• a chamber communicated to insides of the plurality of heat transfer tubes;
• a plurality of burring parts in a tubular shape that are provided to protrude from circumferential edge parts of the plurality of hole parts of the header part toward a sidewall part side of the case, and are externally fitted to the end parts of the respective heat transfer tubes;
• and
• a plurality of extension parts, disposed at a tip circumferential edge part of each of the burring parts, and each of the plurality of extension parts is provided to partially extend from a part of the tip circumferential edge part of each of the burring parts toward the sidewall part side of the case, and each of the plurality of extension parts has a tip part abutting against the sidewall part.