State GUR-50 4**

It holds 48 gallons in the test, 2 gallons less than its 50-gallon sold size. Over one hour from a full tank, it gave 84 gallons in the test (its first-hour rating). Its tank holds 48 gallons, so reheating adds 36 gallons during the first hour. Of 763 gas storage models, 209 give more hot water in the first hour. 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 went to hot water, so its UEF is 0.64. In the test, daily hot water use was set to high (its draw pattern). Of 434 gas storage models with the same draw pattern, 255 have a higher UEF and 95 a lower one. On its draw pattern, the median gas storage UEF is 0.66. Of the energy spent to reheat water, 77% goes into it (its recovery efficiency).

It is the basic model for GS X 50 BCUT 4**, GS6-50-BCUT 4**, and GW8-50-BCUT 4**. All of its test figures are shared by 4 other basic models. Each of the 4 other brands lists one of them. For the full group, see the A. O. Smith GUR-50 4**.