STATE ATM-180M-N 1**

This site computed the 178 therms figure, not the registry. We combined the registry's UEF, the ratio of hot water delivered to energy used, with the daily hot-water draw the DOE test sets for the high draw pattern. The registry lists a UEF of 0.95 for this model in DOE CCD data retrieved on 2026-09-19. The 178 therms figure therefore holds only at the federal test's daily draw. A household that draws more hot water than the test would use more gas. A household that draws less would use less. The registry does not show how large that change would be for a given home, so that figure is not available. Each step of the calculation is described in how the annual cost is calculated.

Among the 397 gas tankless models registered at the high draw pattern, this unit ranks 45th lowest in energy use. The high draw pattern describes a larger household, or one where showers and laundry overlap. A home that matches that description is the case the 178 therms figure was computed for. A smaller household with lighter hot-water use does not match the high draw pattern, so the figure would not describe its use. The registry also lists a maximum flow rate in gallons per minute of 5.4 for this model. The registry does not show which combination of fixtures running together that flow covers. If your household sits outside the high draw pattern, the selector by fuel, space and size lists models by other criteria.

The running cost is not given in this text, because it depends on your state's average residential gas price. The page applies that price to the 178 therms figure at the high draw pattern once you enter your ZIP in the cost calculator for your own ZIP. The running cost on a rate other than your state average is not available here. The installed-price range appears in its own block with its source and date. It is a modeled range, not a quote. If you are checking a replacement, you can find a same-class replacement by model number. Then compare that model's annual energy with the 182 therms median for gas tankless models at the high draw pattern.