A. O. SMITH GUC-50 4**

This is the A. O. SMITH GUC-50 4**, a gas tank. Its UEF, the ratio of hot water delivered to energy used, is 0.61, and the registry does not list annual energy. This site computed 277 therms from that UEF and the DOE test's daily hot-water draw for the high draw pattern. The figure holds only at that test draw, and real households can use more or less than the test assumes. These data do not show how far any one home departs from the test. The source is DOE CCD, retrieved 2026-09-19, and the method is described on the methodology page.

Among the 414 models registered as a gas tank at the high draw pattern, this one ranks 400th lowest in energy use. That places it in the highest quarter of its class for energy use. It uses 17 therms more than the class median of 260 therms. The first hour rating, the gallons of hot water available in the first hour from a full tank, is 84. The rated volume is 48 gallons. The high draw pattern describes a larger household, or one where showers and laundry overlap. A reader who wants low gas use should note that most models in this class use less. Same-class alternatives can be found with the replacement finder.

The running cost is not stated in the text, because it depends on your state's average residential gas price. Applying that price to 277 therms gives a yearly cost at the federal test's draw, not a prediction of your bill. The cost calculator makes that calculation from your ZIP. The 17 therms gap to the class median of 260 therms is the extra gas at the test draw. Its cost follows from your own rate. This comparison covers only gas tanks at the high draw pattern; other fuels and draw patterns are not compared here. To filter by fuel, space and size, use the water heater selector. The modeled installed-cost range is in its own block and is not restated here.