A. O. SMITH HETF-50 1**

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.92 for this model. The registry does not publish annual energy use. This site computed 3,531 kWh of electricity from that UEF and the DOE test's daily hot-water draw for the medium draw pattern. The source is DOE CCD, retrieved 2026-09-19. Among the 426 models registered as an electric tank at this draw pattern, the model ranks 213th lowest for energy use. Its difference from the class median of 3,531 kWh is 0 kWh, so under the same test conditions it uses neither more nor less than the typical model in its class.

The rated volume is 45 gallons, and the first hour rating, the gallons of hot water available in the first hour from a full tank, is 74 gallons. Both are registry values. They describe capacity under test conditions, not a household's actual supply. The energy figure applies to households whose hot-water use resembles the medium draw pattern. For a household with much higher or lower use, 3,531 kWh does not apply directly, because the calculation uses the test's fixed daily draw. This page has no figure for other draw patterns. Readers who want a different size or fuel can start from the water heater selector.

The annual figure is a quantity of electricity, not a cost. Running cost depends on your own utility electricity tariff, so this text gives none. The cost calculator applies the rate for your ZIP to 3,531 kWh, and the methodology page explains how the annual cost is calculated. Because this model sits at the class median of 3,531 kWh, a same-class unit with lower energy use would cost less to run at the same rate, and one with higher use would cost more. To look for one, find a same-class replacement by model number. The modeled installed-cost range appears in its own block with its source and date; it is not a quote.