A horizontal electric hot water heater works the same way as a vertical one. The direction refers to the mounting configuration. In some spaces, horizontal mounting provides additional room for storage and allows installation in spaces not tall enough for vertical mounting.
A horizontally mounted hot water heater features connecting tubes to hold the heater in place on the wall, whereas a vertically mounted hot water heater stands in place. Other than that, the process remains the same.
Some of the important characteristics to look for in a hot water heater include an indirect air heating element to increase ease of maintenance and reliable overall operation; a heating flange with multiple parallel connected heating elements to allow at least one to operate even if others go out; magnesium anode to fight corrosion of the tank; and an enamel coating on the interior of the tank. Conventional immersion hot water heaters are more difficult to maintain, as the heating element or elements are harder to access in case of repair. Hot water heaters that lack the enamel coating on the interior corrode more quickly, necessitating more frequent replacement. Hot water heaters with external thermometers let the owner set temperatures with less guesswork.