A. O. SMITH GPDNL-40 1**

The figure of 242 therms is computed by this site, not by the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 0.7 with the DOE test's daily hot-water draw for the high draw pattern. The source is DOE CCD, retrieved 2026-09-19. The class median is 260 therms, so this model sits 18 therms lower. Its rank is 90th lowest energy use of 414, which places it in the lowest quarter of its class. The figure holds only at the federal test's daily draw. Measured use in a real home is not available here.

The high draw pattern describes a larger household, or one where showers and laundry overlap. For that pattern, the registry lists a first hour rating, the gallons of hot water available in the first hour from a full tank, of 75 gallons on a rated volume of 38 gallons. The data does not show whether that supply covers a particular household. A household whose daily draw differs from the federal test's does not match the 242 therms figure, and its actual use is not available here. To compare fuel, space and size, the water heater selector works from those inputs.

The running cost is not stated in the text because it depends on the state average residential gas price where the reader lives. Multiplying 242 therms by a local price per therm gives the annual cost. The cost calculator does this from a ZIP, and the methodology page explains how it is calculated. The 18 therms gap to the class median of 260 therms converts the same way, using the same local price. To look for a unit in the same class as GPDNL-40 1**, the same-class replacement search works by model number. The modeled installed-cost range is in its own block on the page, with its source and date.