ARISTON GSN40T1-3-*

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.6 for this model. This site computed the annual figure of 185 therms, not the registry. It used the registry's UEF and the DOE test's daily hot-water draw for the medium draw pattern. That pattern represents a typical multi-person household on a busy morning. The figure applies only at that draw. A household that draws more or less hot water will use a different amount of gas, and this page does not estimate that amount. The DOE CCD data was retrieved on 2026-09-19; the calculation method is documented separately.

Against the 288 models registered as a gas tank at the medium draw pattern, this unit ranks 89th lowest for energy use. The class median is 185 therms, so the difference from the median is 0 therms. That puts it in the second-lowest quarter of its class for energy use. The data here does not show how far apart the neighboring models are. This model's first hour rating, the gallons of hot water available in the first hour from a full tank, is 74 gallons. Its rated volume is 38 gallons. It suits a reader who wants energy use at the class median for a gas tank. It does not suit a household whose busiest hour draws more than the first hour rating. The water heater selector filters by fuel, space and size.

Running cost is not stated in this text. It depends on the state average residential gas price for your location. Multiplying 185 therms by your own gas rate gives a yearly cost at the medium draw pattern. The cost calculator applies the state price from your ZIP code for you. Because this model sits at the class median of 185 therms, its cost would match a median model's at the same rate. The page shows a modeled installed-cost range in its own block, with its source and date. It is a modeled range, not a quote, and this text does not restate it. For a same-class replacement, search by model number.