AMERICAN T-H3J-OS-N 1**

The figure of 178 therms is a computed value, not a reading from a home. This site calculated it from the registry's UEF, the ratio of hot water delivered to energy used. It also used the DOE test's daily hot-water draw for this draw pattern. The registered UEF is 0.95. The fuel is natural gas, and the DOE CCD source was retrieved 2026-09-19. A real household's draw will differ from the test's daily draw, so the figure is a comparison basis. The steps behind the calculation are on the methodology page for annual cost.

This unit ranks 45th lowest in energy use among the 397 models registered as a gas tankless unit at the high draw pattern. That places it in the lowest quarter of its class. The class median is 182 therms, and this unit sits 4 therms below it. The comparison holds only for the high draw pattern, meaning a larger household, or one where showers and laundry overlap. Its maximum flow rate in gallons per minute is 4.7. For a smaller household with a lower draw pattern, this page gives no energy figure, so that value is not available. A household that fits the high pattern can use the water heater selector to filter by fuel, space and size.

The running cost is not stated in the text because it depends on your state average residential gas price. The cost calculator applies that price, from your ZIP, to the 178 therms shown here. Any cost from it holds only for the high draw pattern. The modeled installed-cost range has its own block with its source and date, and it is not a quote. Measured gas use in your own home is not available in this data. To verify a swap, find a same-class replacement by model number. Then compare its annual energy at the same draw pattern.