STATE T-H3-OS-N 1**

The 178 therms figure does not come from the registry itself. This site calculated it from the registry's UEF, the ratio of hot water delivered to energy used. For this model, the UEF is 0.95. The other input is the daily hot-water draw that the DOE test sets for the high draw pattern. The source is DOE CCD, retrieved 2026-09-19. The result describes natural gas use under the federal test's conditions. It is not a measurement taken in any home. The registry also lists a maximum flow rate in gallons per minute of 5.8 for this unit. That rating is not used in the annual energy calculation. The full method is explained on the page about how the annual cost is calculated.

The high draw pattern describes a larger household, or one where showers and laundry overlap. This unit is compared with the 397 models registered as gas tankless units at that pattern. Among them, it ranks 45th lowest for energy use, which puts it in the lowest quarter of its class. Its 178 therms sits 4 therms below the class median of 182 therms. The ranking covers only that class. It does not compare this unit with other heater types or other draw patterns. A home that uses hot water differently from the high draw pattern will not use exactly 178 therms. How far its use would differ is not available here. To check other units in the same class, use find a same-class replacement by model number.

This text does not give a running cost. The cost depends on the average residential natural gas price in the reader's state. The page calculates it from your ZIP by applying that price to the 178 therms per year at the high draw pattern. To see a figure based on your own rate, use the cost calculator for your ZIP. The 4 therms gap below the 182 therms class median is priced at the same rate, so its effect on cost also depends on your state's price. The installed price range appears in its own block, with its source and date. It is a modeled installed-cost range, not a quote from an installer.