LOCHINVAR GPDNT-50 1**

The registry does not print the 242 therms figure. This site calculated it from the model's UEF, the ratio of hot water delivered to energy used, and the DOE test's daily hot-water draw. The registry lists this model's UEF as 0.7. The registry values come from the DOE CCD, retrieved 2026-09-19. So the figure is accurate only at the high draw pattern's federal test draw. A household that uses more hot water than the test assumes will burn more gas than 242 therms a year. A household that uses less will burn less. The registry data does not show how much more or less. The steps behind the calculation are on the page explaining how the annual cost is calculated.

The high draw pattern describes a larger household, or one where showers and laundry overlap. For that use, the registry lists a first hour rating, the gallons of hot water available in the first hour from a full tank, of 75 gallons. The rated volume is 48 gallons. Among the 414 gas tank models registered at the high draw pattern, this model has the 90th lowest energy use. That puts it in the lowest quarter of its class. This ranking only compares models tested at the high draw pattern. It does not apply to a household whose use fits a different draw pattern. To compare other models, use the water heater selector by fuel, space and size.

This text gives no running cost. The cost of 242 therms of natural gas depends on your state's average residential gas price, so the page calculates it from your ZIP in the running cost calculator for your own ZIP. At any single gas price, this model's yearly gas use at the test draw is 18 therms below the class median of 260 therms. So its gas cost at that price is lower than the median model's by the cost of 18 therms. The installed price range on this page is a modeled range, not a quote. To match this unit with another model from the same class, find a same-class replacement by model number.