11 Water heaters for domestic, commercial and industrial use, tankless water heaters, heating boilers, pipes for heating boilers, direct vents for gas water heaters and boilers, heating systems for residential and commercial buildings comprised of boilers, valves, pipes, manifolds, control panel, switches and electrical wire, all sold as a unit; water heating systems comprised of domestic water storage tanks, buffer tanks, steam traps, water pumps, and air filters