1 Scope 1.1 This Standard specifies the methods for determining the energy factor for electric storage tank water heaters and heat pump water heaters. 1.2 This Standard establishes minimum energy efficiency levels for electric storage tank water heaters and heat pump water heaters. 1.3 This Standard applies to
a) electric storage tank water heaters
i) with volumes of 76 to 454 L (20 to 120 US gal);
ii) having electric heater elements with power inputs up to 12 kW; and
iii) designed to heat and store water at a thermostatically controlled temperature equal to or less than 82 ºC (180ºF); and
b) heat pump water heaters that have
i) a maximum current rating of 24 A;
ii) a single-phase maximum voltage of 250 V; and
iii) ancillary equipment necessary for the device to function. 1.4 This Standard does not apply to high-temperature water heaters. 1.5 The tests contained in this Standard are not intended to represent actual efficiencies realized in the field. Instead, these tests provide a standardized method of comparing performance. 1.6 This Standard is written in SI units. The values given in parentheses are for information only. The SI values have been calculated from the US Customary Units measurements found in the US Department of Energy publication 10 CFR, Part 430, appendix E, subpart B.