The U-tube tank heater operates with either water or steam on the tube side and is available in sizes ranging from 4 in. to 12 in. in dia with lengths up to 10 ft in both two- and four-pass designs. The unit can be installed in any new or existing hot water tank and features cast iron heads, copper tubes and baffles, and steel tube sheets and bolting. Units are also available with optional materials of construction such as brass, cupro-nickel, or other alloys as specified.