Rheem SPEX3512

The 628 kWh figure is calculated by this site. The registry does not publish it. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 0.94 with the DOE test's daily hot-water draw. That draw belongs to the very small draw pattern, which covers small units: a single bathroom, or a point-of-use heater under a sink. So the figure describes the SPEX3512 at the federal test's daily draw only. This page does not have energy use at any other daily draw. The registry data comes from DOE CCD, retrieved 2026-09-19. The steps are set out in how the annual cost is calculated.

Within its class, this unit ranks 188th lowest energy use of 271. The class is every model registered as an electric tankless unit at the very small draw pattern. That rank puts it in the second-highest quarter of its class for energy use, above the median given earlier. The registry lists its maximum flow rate in gallons per minute as 0.3. That rating matches the draw pattern's scope, a sink or a single bathroom. A fixture that needs more than 0.3 at once is beyond that rating. For a larger site, the selector by fuel, space and size filters models by those factors.

The text on this page does not give a running cost. The cost of 628 kWh a year depends on your own utility electricity tariff, and this page does not know that tariff. So the page calculates the cost from your ZIP and does not estimate it here. The same applies to the 13 kWh gap above the class median: what it costs depends on your rate. You can check both with the cost calculator on your own ZIP. To compare with the other 271 models in the same class, find a same-class replacement by model number. The installed price has its own block with its source and date. It is a modeled range, not a quote.