Heat exchanger and water heater including the same

A heat exchanger, comprising:

• a plurality of fins each having a main surface and arranged at a distance from one another in a first direction intersecting said main surface;
• and
• a heat conduction pipe including a plurality of through pipes extending along said first direction so as to pass through said plurality of fins and arranged as one connected pipe,
• said heat conduction pipe including
• a first-stage portion where a plurality of first through pipes among said plurality of through pipes are arranged at a first pitch along a second direction intersecting said first direction, and
• a second-stage portion where a plurality of second through pipes among said plurality of through pipes are arranged at a second pitch along said second direction,
• said first through pipes and said second through pipes being equal in number, and
• said first pitch and said second pitch being different from each other.