A. O. SMITH GDVNL-40L 1**

The energy figure of 182 therms of natural gas a year was computed by this site, not the registry. The inputs are the registry's UEF, the ratio of hot water delivered to energy used, and the federal test's daily draw. The listed UEF for this model is 0.61, and the source is DOE CCD, retrieved 2026-09-19. The draw pattern, the standard daily hot-water usage DOE tests against, is medium here, a typical family household on a busy morning. A household that draws more or less hot water than the test will see a different annual figure. How the calculation works is set out on the methodology page.

Against its class, this model uses 182 therms a year, which is 3 therms below the class median of 185 therms. The class is the 288 models registered as a gas tank at the medium draw pattern. This model ranks 73rd lowest in energy use, which puts it in the second-lowest quarter of its class. The comparison holds only at the medium draw pattern. A household with heavier or lighter use cannot read this rank as its own. To compare other fuels or sizes, the water heater selector filters by fuel, space and size.

The first hour rating, the gallons of hot water available in the first hour from a full tank, is 64 gallons for this model. The rated volume is 38 gallons. A household whose busiest hour needs more than 64 gallons is not served by that rating. The figures here are a test result, not a forecast of real household use. Running cost is not stated in this text because it depends on your state's average residential gas price. To see it, enter your ZIP in the cost calculator. To look for another model in the same class, use the same-class replacement search by model number.