American GUC-50 4**

It holds 48 gallons in the test, 2 gallons less than its 50-gallon sold size. It delivers 84 gallons of hot water in the test's first hour. That is 36 gallons more than its tank holds, since it reheats during the hour. Among 763 gas storage models, 209 have a higher first-hour rating. 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, 61% of the energy it uses ends up as hot water (UEF 0.61). In the test, daily hot water use was set to high (its draw pattern). Among 434 gas storage models on its draw pattern, 419 have a higher UEF. A UEF of 0.66 is the median for its type and draw pattern. Of the energy spent to reheat water, 77% goes into it (its recovery efficiency).

It is the basic model for GU61-50T40R 4** and GU81-50T40R 4**. All of its test figures are shared by 3 other basic models. Of those, one or more are under the A. O. Smith, RELIANCE WATER HEATERS, and State brands. For the full group, see the A. O. Smith GUC-50 4**.