Rheem XG40S06EC34U0

The registry does not list 191 therms; this site computes it. It uses two inputs from the registry and the test. The first is the registry's UEF, the ratio of hot water delivered to energy used. The second is the DOE test's daily hot-water draw. For this model the UEF is 0.58, and the draw is the one set for the medium draw pattern. The registry values come from DOE CCD, retrieved 2026-09-19. The figure applies only at the federal test's draw, not at a particular home's actual use. This data does not show how far a real household would be from 191 therms. The exact steps are set out in how the annual cost is calculated.

Within its class, this model ranks 231st lowest in energy use of 288. That places it in the highest quarter of the class for energy use. The class includes every model registered as a gas tank at the medium draw pattern. For capacity, the registry lists a rated volume of 38 gallons. It also lists a first hour rating, the gallons of hot water available in the first hour from a full tank, of 64 gallons. The 191 therms figure describes a household whose use matches the medium draw pattern. A reader who wants lower energy use within the same class can compare other models with the same-class replacement finder by model number.

This text does not state a running cost, because the cost depends on the reader's own gas rate. The page applies the state average residential natural gas price for the reader's ZIP to 191 therms. The same rate also sets what the 6 therms gap to the class median is worth in a given state. Neither amount can be given here without that rate. To see both for your own location, use the cost calculator for your own ZIP. The installed price range appears in its own block on this page, with its source and date. It is a modeled installed-cost range, not a quote.