A. O. SMITH GCB-30R 4**

The figure of 185 therms is a calculation, not a metered bill. This site computed it from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.6 for this model. It also used the daily hot-water draw that the DOE test assigns to the medium draw pattern. The fuel is natural gas, and the source is the DOE CCD, retrieved 2026-09-19. The registry did not supply the annual figure itself. A home that draws more or less hot water than the test assumes will use a different amount. The steps behind the calculation are set out in how the annual cost is calculated.

The class for comparison is the 288 models registered as a gas tank at the medium draw pattern. This model ranks 89th lowest for energy use, which places it in the second-lowest quarter of that class. Its energy use is equal to the class median of 185 therms, so the difference is 0 therms. That rank covers energy use only at this draw pattern. Size is a separate check: the first hour rating, the gallons of hot water available in the first hour from a full tank, is 62, and the rated volume is 29 gallons. A household whose hot-water use is close to the test draw can compare against these figures. A household that needs more than 62 gallons in its busiest hour should look at other sizes with the selector by fuel, space and size.

The running cost is not stated here because it depends on your state's average residential gas price. To estimate it, apply your own rate to the 185 therms figure, or enter your ZIP in the cost calculator. The result holds only for the medium draw pattern and the federal test's daily draw. An installed price range is not published for this model. Its ratings lie outside the range the cost database's model was fitted on, and the range is not stretched past it. If you are comparing this unit against another of the same class, find a same-class replacement by model number and check its 185 therms class median against the same draw pattern.