LOCHINVAR GPDT-50 3**

The 235 therms figure comes from this site's own calculation, not from the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 0.72 with the DOE test's daily hot-water draw. That draw belongs to the high draw pattern, which stands for a larger household, or one where showers and laundry overlap. The figure therefore holds only at the federal test's daily hot-water draw. A home that draws more or less hot water than the test assumes will use a different amount of gas. The size of that difference is not available in this data. The source is DOE CCD, retrieved 2026-09-19. The full steps are set out in how the annual cost is calculated.

This model is compared with the 414 models registered as a gas tank at the high draw pattern. Its 235 therms sits 25 therms below the class median of 260 therms. That places it 50th lowest of 414, in the lowest quarter of its class for energy use. The comparison holds only inside this class; the data gives no ranking against other fuels or heater types. Its first hour rating, the gallons of hot water available in the first hour from a full tank, is 79 gallons. Its rated volume is 48 gallons. The registry does not record whether that covers a particular home's busiest hour. To compare a like-for-like unit, use the tool to find a same-class replacement by model number.

The text of this page does not state a running cost. The cost of 235 therms a year depends on the reader's state average residential gas price. For that reason, the page computes it from the reader's ZIP. That result applies only at the high draw pattern and at the 0.72 UEF. You can check the same figure against your own rate with the cost calculator on your own ZIP. The installed-cost range appears in its own block, with its source and date. It is a modeled range, not a quote. This model's energy use for a smaller household is not available here. The data holds no figure for this model at any draw pattern other than high.