Rheem RHE40S

This site computed the 204 therms figure. It is not taken directly from the registry. The calculation combines the registry's UEF, the ratio of hot water delivered to energy used, with the DOE test's daily hot-water draw for the high pattern. This model's UEF is 0.83, from the DOE CCD, retrieved 2026-09-19. The steps are set out on the page about how the annual figure and cost are calculated. Among the 414 gas tank models at the high draw pattern, it ranks 25th lowest for energy use. That places it in the lowest quarter of its class. The figure holds only at the test's draw. A household that uses more or less hot water will have a different yearly total, and this page does not estimate that total.

The high draw pattern represents a larger household, or one where showers and laundry overlap. This model's first hour rating, the gallons of hot water available in the first hour from a full tank, is 87 gallons. Its rated volume is 37 gallons. The 204 therms figure applies to a home whose busiest hour stays within that first hour rating. A home whose busiest hour needs more hot water falls outside the tested condition, and the figure does not describe it. To compare other registered units, use the water heater selector by fuel, space and size. To check units in the same class, search same-class replacements by model number.

The running cost is not given in this text because it depends on your state's average residential gas price. The cost calculator for your own ZIP applies that price to the 204 therms figure. At any single gas price, this model's 56 therms gap below the class median means a lower yearly gas cost than the median model. The size of that cost gap depends on the price. An installed price range is not published for the Rheem RHE40S. Its ratings fall outside the range that the cost database's model was fitted on. This site does not extend that range past its limits, so the installed price is not available here.