AMERICAN ATM-140M-N 1**

The figure of 178 therms is a yearly natural gas total for AMERICAN ATM-140M-N 1** at the high draw pattern. This site computed it, not the registry, from the registry's UEF and the DOE test's daily hot-water draw for that pattern. UEF, the ratio of hot water delivered to energy used, is 0.95 for this model. The data comes from DOE CCD, retrieved 2026-09-19. The comparison class is the 397 models registered as a gas tankless unit at the high draw pattern, and its median is 182 therms. This unit sits 4 therms below that median, at 45th lowest energy use, which places it in the lowest quarter of its class.

The high draw pattern describes a larger household, or one where showers and laundry overlap. If that matches the home, the 178 therms figure is the relevant one to check, and the 4 therms gap to the 182 therms median shows how far this model sits from its class. The maximum flow rate in gallons per minute is 4.1 for this model. The data does not say how many outlets that flow can serve at a given inlet water temperature, so that is not available here. If the home's real usage differs from the federal test's daily draw, actual gas use will differ from this figure, and the size of that difference is not available either. To compare by fuel, space and size, use the water heater selector.

The running cost is not written in this text because it depends on the average residential gas price in the reader's state. The cost calculator applies that price, taken from the reader's ZIP, to the 178 therms figure at the high draw pattern. A rate that differs from the state average will change the result in proportion to the gas used. How the annual cost is calculated sets out the method and its inputs. The modeled installed-cost range appears in its own block on this page with its source and date, and it is a modeled range, not a quote. To find a same-class model to compare with ATM-140M-N 1**, search by model number.