Lochinvar GCR-40 2**

It holds 38 gallons in the test, 2 gallons less than its 40-gallon sold size. Starting full, it gives 80 gallons of hot water in its first hour of use. That is 42 gallons more than its tank holds, since it reheats during the hour. In the first hour, 323 of the 763 gas storage models give more hot water. Among gas storage models, the median first-hour rating is 78 gallons.

On Oct 26, 2026, this heater was not listed as ENERGY STAR certified. In tests, 64% of the energy it uses ends up as hot water (UEF 0.64). In the test, daily hot water use was set to high (its draw pattern). Its UEF is lower than that of 255 of the 434 gas storage models with its draw pattern. For its type and draw pattern, the UEF runs from 0.61 to 0.90. Of the energy spent to reheat water, 74% goes into it (its recovery efficiency).

A tag or quote may show any of its 5 model numbers. There are 4 more basic models with the same test figures. They are listed under 4 other brands, one each. For the full group, see the A. O. Smith GCR-40 2**.