ARISTON GSN40L2-3-*

The figure of 185 therms is computed by this site, not by the registry. It starts from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.6 for this model. The calculation then applies the daily hot-water draw that the DOE test sets for the medium draw pattern. The source is DOE CCD, retrieved 2026-09-19. A household that draws more or less hot water than that test will use a different amount. It is not a measurement of any single installation. The calculation method is documented on its own page.

Against the 288 models registered as a gas tank at the medium draw pattern, this unit ranks 89th lowest for energy use. That places it in the second-lowest quarter of its class. Its energy use equals the class median of 185 therms, so the difference is 0 therms. The first hour rating, the gallons of hot water available in the first hour from a full tank, is 64 gallons. The rated volume is 38 gallons. These ratings suit a household whose hot-water use matches the medium draw pattern. For a household with a heavier draw, the registry data on this page do not show how the unit performs. The same-class replacement search lists other units by model number.

The running cost is not stated in this text, because it depends on your state average residential gas price. It is 185 therms multiplied by that price, so the same unit costs different amounts in different states. The cost calculator applies your own ZIP to this figure. This model sits 0 therms from the class median of 185 therms. A unit at the median would use the same energy. The installed price range is shown in its own block as a modeled range, not a quote. For a different fuel or size, use the water heater selector. The data here cover only the medium draw pattern, so how the figure changes under another pattern is unknown.