LOCHINVAR GPVL-40 2**

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.67 for this model. This site combined that value with the DOE test's daily hot-water draw for the medium draw pattern to reach 165 therms of natural gas per year. The registry does not publish that annual figure, so it is a computed value based on DOE CCD data retrieved on 2026-09-19. The model has the 20th lowest energy use of 288 gas tank models at the medium draw pattern. That puts it in the lowest quarter of its class, 20 therms below the class median of 185 therms. The figure applies to the test's daily draw only. This page holds no measurement of energy use in any particular home.

The first hour rating, the gallons of hot water available in the first hour from a full tank, is 73 gallons for this model, and the rated volume is 38 gallons. The 165 therms figure suits a household whose hot-water use resembles the medium draw pattern, meaning a typical household on a busy morning. It suits a household with heavier or lighter use less well, because the figure is tied to that one draw pattern and this page has no value for the others. Whether 73 gallons covers a specific household's busiest hour is not something the registry data settles. To narrow options by fuel, space and size, use the water heater selector. To look for a same-class unit, find a replacement by model number.

The running cost is not stated here because it depends on the state average residential gas price, which differs by location. Multiplying 165 therms by the price per therm that applies to you gives a yearly cost at the medium draw pattern. The cost calculator on your own ZIP does this for you. The 20 therms gap to the class median of 185 therms scales with the same price, so it is a difference in therms, not a fixed amount of money. The methodology page explains how the annual cost is calculated. The modeled installed-cost range appears in its own block on this page, with its source and date, and it is not a quote.