Lochinvar GCF-40 1**

It holds 38 gallons in the test, 2 gallons less than its 40-gallon sold size. It delivers 70 gallons of hot water in the test's first hour. That is 32 gallons more than its tank holds, since it reheats during the hour. Of 763 gas storage models, 510 give more hot water in the first hour. Among gas storage models, the median first-hour rating is 78 gallons.

It was not listed as ENERGY STAR certified on Oct 26, 2026. 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 medium (its draw pattern). Of 288 gas storage models with the same draw pattern, 43 have a higher UEF and 227 a lower one. For its type and draw pattern, the median UEF is 0.60. Of the energy spent to reheat water, 73% goes into it (its recovery efficiency).

It is the basic model for LTL04040ES 1*1 and LTN04040ES 1**. There are 5 more basic models with the same test figures. They are listed under 5 other brands, one each. For the full group, see the A. O. Smith GCF-40 1** page.

It may qualify for one rebate program in one state.