A water heater for heating potable water used in a boat or vehicle. Each of the tiles includes an upper edge configured to be oriented upward relative to the mounting surface and a lower edge configured to be oriented downward relative to the mounting surface. A simple design in which leaks are avoided results if a reservoir wall of the tank housing and a housing wall of the air cleaning unit are positioned adjacent to one another and the bleed device comprises a bleed opening which passes through the reservoir wall and the housing wall. The transistor driving circuit increases an output voltage of the resistive load to a desired output voltage level over a time interval in response to first and second voltage signals being applied to the first and second electrical nodes, respectively, when the first and second capacitors are receiving first and second pulse width modulated voltage signals, respectively, over the time interval. Wherein, the shaft member is connected between the position limiting member and the specimen-fixing member, and the specimen is fixed between the base and the specimen-fixing member.