ARISTON PV40SLN*

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.64 for this gas tank. This site computed 173 therms from that UEF and the DOE test's daily hot-water draw for the medium draw pattern. The registry does not publish that annual figure itself. The source is DOE CCD, retrieved 2026-09-19. Among the 288 models registered as a gas tank at the medium draw pattern, this one ranks 44th lowest in energy use. That places it in the lowest quarter of its class. The method is explained in how the annual cost is calculated.

The figure of 173 therms holds for the medium draw pattern only. A household with heavier or lighter use will see a different result, and this page has no figure for other draw patterns. The first hour rating, the gallons of hot water available in the first hour from a full tank, is 71 gallons for this model. Its rated volume is 39 gallons. Those two values describe supply, not energy use. This data does not show whether they cover a given household's busiest morning. A household that needs more hot water in the first hour should compare that rating with its own peak demand. The water heater selector filters by fuel, space and size.

The running cost is not stated here because it depends on the state average residential gas price. Multiply 173 therms by that price to estimate the yearly cost at the medium draw pattern. The cost calculator does this from the reader's own ZIP. The 12 therms gap from the class median of 185 therms carries over to the cost at whatever price applies. A model at the median would use 12 therms more gas a year under the same test conditions. Actual use in a home can differ from the federal test, and this page cannot measure that. For a same-class alternative, find a replacement by model number.