; and (II) are designed to transfer thermal energy from 1 temperature level to a different temperature level for the purpose of heating water; (iv) solar thermal-assisted electric storage units; and (v) solar thermal-assisted fossil fuel storage units. (B) Exclusions Unless otherwise determined by the Secretary under section 325(e)(7)(B), the term water heater does not include— (i) electric storage type units described in subparagraph (A)(i)(III) that— (I) are designed and marketed exclusively for commercial building applications; and (II) (aa) are designed, constructed, inspected, tested, and stamped in accordance with Section IV, Part HLW, or Section X of the Boiler and Pressure Vessel Code promulgated by the American Society of Mechanical Engineers; (bb) exclusively use 3-phase electricity, are designed and marketed to provide outlet hot water at a thermostatically controlled temperature of 180 degrees Fahrenheit or greater, and operate only at rated voltages of not less than 208 volts; or (cc) exclusively use single-phase electricity, are designed and marketed to provide outlet hot water at a thermostatically controlled temperature of 180 degrees Fahrenheit or greater, and operate only at a rated voltage of 277 volts; or (ii) gas storage type units described in subparagraph (A)(i)(I) that— (I) are designed and marketed exclusively for commercial building applications; and (II) are designed, constructed, inspected, tested, and stamped in accordance with Section IV, Part HLW, of the Boiler and Pressure Vessel Code promulgated by the American Society of Mechanical Engineers. (C) Multi-input electric storage water heater The term multi-input electric storage water heater means a product that— (i) is not a heat pump type unit described in subparagraph (A)(iii)