Water heater

A water heater comprising a casing including a casing body having an opening in a front portion, and a door configured to open and close the opening, wherein

• the casing accommodates:
• a burner body including a flat burner having a downward combustion surface;
• a fan case being in communication with the burner body and lying on its side;
• a vertical shaft fan disposed in the fan case and configured to supply a mixture gas containing combustion air and fuel gas to the burner body;
• and
• an ignition electrode disposed below the flat burner, wherein
• the burner body includes:
• a main burner body unit having an introduction port through which the mixture gas is supplied in a substantially central portion of an upper surface thereof, and the flat burner on a lower surface thereof;
• and
• an introducing unit being in communication with the introduction port, protruding upward from the upper surface of the main burner body unit, and laterally having an inlet port being in communication with the fan case, wherein
• an inner surface of an opposite wall section facing the inlet port in a peripheral wall of the introducing unit has a substantially vertical surface, and
• a discharging portion of the ignition electrode is disposed within a projection plane when the peripheral wall of the introducing unit is projected downwardly.