JOHN WOOD GPDT-50 3**

The 235 therms figure is computed by this site, not taken directly from the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, with the DOE test's daily hot-water draw for the high pattern. For this model the UEF is 0.72, as listed in the DOE CCD data retrieved on 2026-09-19. The figure therefore describes gas use at the federal test's draw, not measured use in any particular home. A home whose daily hot-water use differs from the test draw would see a different yearly figure. The steps behind the number are set out in how the annual cost is calculated.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. Within that group the model ranks 50th lowest energy use of 414, which places it in the lowest quarter of its class for energy use. Its first hour rating, the gallons of hot water available in the first hour from a full tank, is 79 gallons at a rated volume of 48 gallons. A plumber or seller checking a quote can match these registry figures against the label on the unit. Readers comparing it with other gas tanks at the same draw pattern can use the same-class replacement search by model number.

The class comparison covers only the 414 models registered as a gas tank at the high draw pattern. It says nothing about electric, heat pump or tankless units, and those are grouped differently in the selector by fuel, space and size. The 235 therms figure also does not describe a smaller household drawing less hot water than the high pattern assumes. The running cost is not stated in this text, because it depends on your state's average residential gas price. The page computes it from your ZIP instead, applied to the 235 therms yearly figure. You can repeat that step with the cost calculator on your own ZIP. The installed price range appears in its own block, as a modeled range rather than a quote.