Rheem RHE40SP

The 148 therms figure comes from this site's calculation, not from the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, with the daily hot-water draw the DOE test sets for the medium pattern. This model's UEF is 0.75, taken from DOE CCD data retrieved 2026-09-19. At that draw, the model ranks 1st lowest in energy use among 288 gas tank models registered at the medium draw pattern. The figure holds only at the test's daily draw. A household that uses more or less hot water than the test assumes will have a different yearly total. The steps from energy figure to yearly cost are set out in how the annual cost is calculated.

The medium draw pattern stands for a typical household's daily hot-water use under the DOE test. This model's first hour rating, the gallons of hot water available in the first hour from a full tank, is 68 gallons. Its rated volume is 37 gallons. A household whose busiest hour stays within 68 gallons is close to the conditions behind the 148 therms figure. A household that draws more than that in its peak hour falls outside those conditions, so the test figure does not describe its use. To compare heaters by a different fuel, space or demand, use the selector by fuel, space and size. To check other units in this same class, find a same-class replacement by model number.

This page gives no running cost in the text. The cost of 148 therms of natural gas a year depends on your state's average residential gas price. The page computes that cost from your ZIP, and the cost calculator on your own ZIP runs the same calculation. The 37 therms gap below the 185 therms class median is a difference in energy, so it holds at any gas price. An installed price range is not available for this model. Its ratings lie outside the range the cost database's model was fitted on, and the site does not stretch the range past it. A quote for this unit therefore cannot be checked against a published range on this page.