A. O. SMITH GPDX-50L 3**

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.73 for this model. This site combines that value with the daily hot-water draw the DOE test uses for the high draw pattern to get 232 therms of natural gas per year. The registry does not publish that annual figure itself. It comes from DOE CCD data retrieved on 2026-09-19, and the steps are on the methodology page. The class is the 414 models registered as a gas tank at the high draw pattern, and its median is 260 therms. This model sits 28 therms below that median, at 33rd lowest, which places it in the lowest quarter of its class for energy use.

The first hour rating, the gallons of hot water available in the first hour from a full tank, is 118 for this model, and the rated volume is 48 gallons. The high draw pattern describes a larger household, or one where showers and laundry overlap, so the 232 therms figure applies to that kind of use. A household with a lighter draw is not covered by this figure, and an annual energy value for other draw patterns is not available for this model on this page. Whether 118 gallons meets a particular household's peak demand is not something the registry data settles. The water heater selector filters by fuel, space and size if the fit needs checking.

The running cost is not stated in the text because it depends on the state average residential gas price, which differs by reader. The cost calculator takes a ZIP and applies that price to the 232 therms figure. The result stays tied to the high draw pattern and the federal test's daily draw, not to actual household use. Real gas use can be higher or lower than 232 therms, and the data here does not say by how much. The cost calculator does this on your own ZIP. For a same-class alternative, find a replacement by model number using GPDX-50L 3**. The modeled installed-cost range appears in its own block on this page and is not repeated here.