State FMDV-40 2**

It holds 38 gallons in the test, 2 gallons less than its 40-gallon sold size. Starting full, it gives 57 gallons of hot water in its first hour of use. That is 19 gallons more than its tank holds, since it reheats during the hour. In the first hour, 717 of the 763 gas storage models give more hot water. The median gas storage model gives 78 gallons in its first hour.

As of Oct 26, 2026, it was not listed as ENERGY STAR certified. In tests, 59% of the energy went to hot water, so its UEF is 0.59. Its test ran at the medium level of daily hot water use. Among 288 gas storage models on its draw pattern, 185 have a higher UEF. For its type and draw pattern, the UEF runs from 0.57 to 0.75. The water took in 76% of the energy used to reheat it (its recovery efficiency).

It is sold as GS6-40-MDV 2** and SCI-40-MDV 2**. All of its test figures are shared by 4 other basic models. They are listed under 4 other brands, one each. For the full group, see the A. O. Smith FMDV-40 2**.