Water heater

FIG. 1 is a front, top and right side perspective view of a water heater, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The parts shown in the broken lines do not form part of the claimed design.