LOCHINVAR GPDX-50L 3**

This site calculates the 232 therms figure. The registry does not publish it. The calculation combines the model's UEF, the ratio of hot water delivered to energy used, with the DOE test's daily hot-water draw for the high draw pattern. The UEF for the GPDX-50L 3** is 0.73, as listed in the DOE Compliance Certification Database, retrieved 2026-09-19. The result applies only at the federal test's daily draw. This data does not show gas use for a household whose daily hot-water use differs from that draw. Each step, including the draw volume used, is explained in how the annual energy and cost figures are calculated.

The GPDX-50L 3** was tested at the high draw pattern, which describes a larger household, or one where showers and laundry overlap. Its first hour rating, the gallons of hot water available in the first hour from a full tank, is 118 gallons from a rated volume of 48 gallons. Among the 414 gas tank models at that draw pattern, its energy use is in the lowest quarter. The rating is for natural gas, so it does not apply to a home without a gas supply. This data does not include its energy use at other draw patterns. To check it against other units, use the same-class replacement search by model number or the water heater selector by fuel, space and size.

This text states no running cost because the cost depends on your state's average residential natural gas price. The page looks up that price from your ZIP and applies it to the 232 therms a year at the high draw pattern. To repeat the calculation for another location, use the water heater cost calculator for your ZIP. At any one gas price, the cost gap to the class median is the 28 therms gap multiplied by that price. The installed price range appears in its own block with its source and date. It is a modeled range, not an installer's quote.