A. O. Smith GCR-40 2**

It holds 38 gallons in the test, 2 gallons less than its 40-gallon sold size. Over one hour from a full tank, it gave 80 gallons in the test (its first-hour rating). Reheating lets it give 42 gallons beyond the 38 gallons in its tank. Of 763 gas storage models, 323 give more hot water in the first hour. The median gas storage model gives 78 gallons in the first hour of the test.

It was not listed as ENERGY STAR certified on Oct 26, 2026. In tests, 64% of the energy went to hot water, so its UEF is 0.64. Its test simulated a day of high hot water use (its draw pattern). Of 434 gas storage models with the same draw pattern, 255 have a higher UEF. For its type and draw pattern, the median UEF is 0.66. Of the energy spent to reheat water, 74% goes into it (its recovery efficiency).

It is the basic model for GCR-40 2** and GCR-40 2*1. All of its test figures are shared by 4 other basic models. They are listed under 4 other brands, one each.