Lennox WHGS040T40NPXS****

This site computed the 242 therms figure; the registry does not list it. The calculation uses two inputs. One is the registry's UEF, the ratio of hot water delivered to energy used. The other is the DOE test's daily hot-water draw for the high draw pattern. This model's UEF is 0.7, from DOE CCD data retrieved 2026-09-19. At that draw, it ranks 90th lowest in energy use of the 414 gas tank models at the high draw pattern. That puts it in the lowest quarter of its class. The figure holds only at the test's draw. A household that uses more or less hot water will use a different amount of gas, and this data does not show how much. The page on how this site calculates annual energy and cost explains the calculation.

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 78 gallons. The rated volume is 38 gallons. The 18 therms gap to the class median applies only among gas tank models at the high draw pattern. It does not compare this unit with other fuels or heater types, because those belong to other classes. The 242 therms figure does not describe a smaller household that draws less hot water. The selector by fuel, space and size lists models of other fuels and sizes. To match this unit within its own class, use the same-class replacement search by model number.

The text does not give a running cost because the cost depends on your state's average residential gas price. The page takes that price from your ZIP and applies it to 242 therms a year at the high draw pattern. The 18 therms gap to the 260 therms class median becomes a cost gap only at that same state rate. To check the figure for a different ZIP, use the cost calculator for your own ZIP. This data cannot show your actual gas bill. That bill depends on your household's real hot-water use and on changes in the gas price. The installed-cost range has its own block on the page, with its source and date. It is a modeled range, not a quote.