A. O. SMITH GCRL-40 4**

UEF, the ratio of hot water delivered to energy used, is 0.58 for this model in the registry. This site multiplies that UEF by the federal test's daily hot-water draw for the medium pattern to reach 191 therms. The registry does not publish this figure. The source data is DOE CCD, retrieved 2026-09-19. The value applies only at that daily draw. A household that uses more or less hot water will use a different amount of gas. The class median is 185 therms, which puts this model 6 therms above it. Its rank of 231st lowest of 288 places it in the highest quarter of its class for energy use. The calculation method is described on its own page.

The first hour rating, the gallons of hot water available in the first hour from a full tank, is 67 gallons. The rated volume is 38 gallons. A household near the medium draw pattern can compare that first hour rating with its own busiest hour. This model suits a reader who needs that supply and accepts energy use 6 therms above the class median of 185 therms. It suits less well a reader who ranks models mainly by low gas use, because many models in the class use less gas. A reader who also filters by fuel or space can use the water heater selector.

The running cost is not stated here. It depends on your state average residential gas price, which this text does not assume. The cost calculator applies that price, taken from your ZIP, to 191 therms at the medium draw pattern. The result holds only for the federal test's daily draw, not for your actual hot-water use. The modeled installed-cost range appears in its own block on this page, with its source and date. It is a modeled range, not a quote. If you need a unit of the same class, you can find a replacement by model number starting from GCRL-40 4**.