A. O. SMITH UPVA-24K 1**

The figure of 635 kWh was computed by this site, not taken from the registry. It uses the registry's UEF, the ratio of hot water delivered to energy used, which is 0.93 for this model. That value is applied to the DOE test's daily hot-water draw for the very small draw pattern. The fuel is electricity, and the source is the DOE CCD, retrieved 2026-09-19. The result holds only at that test draw. A home that draws more or less hot water than the test assumes will use a different amount, and this page does not estimate it. The calculation method is described in how the annual cost is calculated.

Among the 271 models registered as an electric tankless unit at the very small draw pattern, this model sits 20 kWh above the class median of 615 kWh. Its rank of 218th lowest energy use puts it in the highest quarter of its class for energy use. Its maximum flow rate in gallons per minute is 0.2. That suits small units, such as a single bathroom or a point-of-use heater under a sink, where the very small draw pattern applies. It does not suit a reader who needs more flow than 0.2 gallons per minute, or one whose priority is the lowest energy use in this class. To compare models of the same class, you can find a same-class replacement by model number.

The running cost is not stated in the text, because it depends on your own utility electricity tariff. The yearly 635 kWh is the quantity your rate applies to, so a rate change alters the cost but not the energy figure. To see the cost for your ZIP, use the cost calculator on your own ZIP. The 20 kWh gap to the class median of 615 kWh is a difference in electricity use only, and what it costs also depends on that rate. This page has no measured household use for this model, so actual use in a given home is unknown. For a different fuel, space or size, the selector by fuel, space and size covers those.