A. O. SMITH GPDL-40 3**

The registry does not print the 163 therms figure itself. This site computed it from the model's UEF, the ratio of hot water delivered to energy used, which is 0.68. The other input is the DOE test's daily hot-water draw for the medium pattern. The source is DOE CCD, retrieved 2026-09-19. The figure holds only at that test draw. A home that draws more hot water each day will use more gas, and one that draws less will use less. Within its class, the model ranks 5th lowest in energy use of 288, which places it in the lowest quarter. That class holds only gas tank models at the medium draw pattern. The steps are set out in how this site calculates annual energy and cost.

The medium draw pattern models a typical mid-sized household on a busy morning. This model's first hour rating, the gallons of hot water available in the first hour from a full tank, is 74 gallons. Its rated volume is 38 gallons. A home whose peak-hour hot-water demand stays within 74 gallons matches the conditions behind the 163 therms figure. A home whose busy hour needs more than that does not match them. For that home, the 5th rank does not carry over, because DOE compares such units under a different draw pattern. Models in other classes can be filtered with the water heater selector by fuel, space and size. A same-class match for an existing unit can be found through replacement lookup by model number.

This text states no running cost for the A. O. SMITH GPDL-40 3**. The cost equals 163 therms multiplied by the average residential natural gas price in your state. That price varies by state, so the cost calculator for your own ZIP applies your state's rate. The 22 therms gap to the class median is also given in therms. Its value in money depends on the same rate. The installed price range appears in its own block, with its source and date. It is a modeled range, not a quote. This model's energy use at draws other than the federal test's is not available. Its actual use in any particular home is also unknown.