A. O. SMITH G9-UT5040NVR 5**

The 264 therms figure does not come from the registry. This site computed it from the model's UEF, the ratio of hot water delivered to energy used. The registry lists that ratio as 0.64. The calculation also uses the DOE test's daily hot-water draw for the high pattern. The UEF comes from DOE CCD, retrieved 2026-09-19. Among the 414 gas tank models at this pattern, the unit ranks 236th lowest in energy use. That places it in the second-highest quarter of its class for energy use. Under the same test draw, it uses 4 therms a year more than the class median. A household that draws more or less hot water than the test assumes will use a different amount. That amount is not available here.

The high draw pattern describes a larger household, or one where showers and laundry overlap. The registry lists a first hour rating, the gallons of hot water available in the first hour from a full tank, of 78 gallons. The tank's rated volume is 48 gallons. The first hour rating covers peak-hour demand up to 78 gallons. The registry figures do not cover demand above that. The 264 therms estimate applies only at the high pattern's test draw, so it does not describe a smaller household's use. To compare other gas tanks, use the water heater selector by fuel, space and size. To match this class from a model number, see same-class replacement by model number.

This text does not state the running cost. The cost depends on your state's average residential gas price, applied to the 264 therms yearly use at the high draw pattern. The page computes that cost from your ZIP, and the cost calculator for your own ZIP shows the result. Your rate also decides how much the 4 therms gap to the class median adds to the yearly cost. The steps are set out in how the annual cost is calculated. The installed price range on this page is a modeled installed-cost range, not a quote. Its source and date appear in its own block.