John Wood GCFL-40 1**

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 65 gallons in the test (its first-hour rating). That is 27 gallons more than its tank holds, since it reheats during the hour. In the first hour, 600 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, 66% of the energy it uses ends up as hot water (UEF 0.66). Its test simulated a day of medium hot water use (its draw pattern). Of 288 gas storage models with the same draw pattern, 26 have a higher UEF and 256 a lower one. For its type and draw pattern, the UEF runs from 0.57 to 0.75. The water took in 77% of the energy used to reheat it (its recovery efficiency).

Its 2 model numbers are JW640S40P-AV-ES2 1*1 and JW8640S40N-AV-ES2 1**. Its test figures match those of 5 other basic models. Each of the 5 other brands lists one of them. For the full group, see the A. O. Smith GCFL-40 1**.

In one state, one rebate program may accept it.