AMERICAN ATM-180M-N 1**

The figure of 178 therms of natural gas is computed by this site, not by the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 0.95 with the DOE test's daily hot-water draw for the high draw pattern. That pattern describes a larger household, or one where showers and laundry overlap. The source is DOE CCD, retrieved 2026-09-19. The figure holds only at the federal test's daily draw, so a home that uses more or less hot water will differ. The registry lists a maximum flow rate in gallons per minute of 5.4. The method is set out in how the annual cost is calculated.

Among the 397 models registered as a gas tankless unit at the high draw pattern, this model has the 45th lowest energy use of 397, which places it in the lowest quarter of its class. Its 178 therms is 4 therms below the class median of 182 therms. The comparison covers energy use only, at the federal test's daily draw. It does not rank flow; the maximum flow rate of 5.4 is a separate registry value. The figure applies to a larger household on natural gas. It does not describe a household with a lighter draw, because the 178 therms was not computed for that pattern. To compare another unit, find a same-class replacement by model number.

The running cost is not stated here because it depends on the state average residential gas price, and this page does not assume one. The cost calculator on your own ZIP applies your state's price to the 178 therms at the high draw pattern. The installed price range is shown in its own block with its source and date. It is a modeled installed-cost range, not a quote, and it is not repeated here. The registry data give no measured field use for this model, so how far a home departs from 178 therms is unknown. If the household's draw is different, the selector by fuel, space and size starts from those inputs instead.