RELIANCE WATER HEATERS ATI-199B-N 1**

The 206 therms figure is computed by this site; it is not taken directly from the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, with the DOE test's daily hot-water draw for the high draw pattern. For this model the UEF is 0.82. The source is the DOE Compliance Certification Database (CCD), retrieved 2026-09-19. The result holds only at the federal test's daily draw. A home that draws more or less hot water each day will use a different amount of gas. The registry records no actual use in any home, so that amount is not available here. The steps behind the figure are set out in how the annual cost is calculated.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. The registry lists this unit's maximum flow rate in gallons per minute as 5.2. Among the 397 gas tankless units registered at the high draw pattern, it ranks 229th lowest for energy use. That places it in the second-highest quarter of its class. Because it sits above the class median, at least half of the class uses less gas at this draw pattern. A reader whose household matches the high draw pattern can compare units in the same class with a same-class replacement search by model number. The data does not show how the unit performs outside the federal test.

The running cost is not written here, because it depends on your state's average residential gas price. Multiplying 206 therms by your gas price gives the yearly figure at the high draw pattern. The page computes it from your ZIP in the cost calculator for your own ZIP. The 24 therms gap to the class median follows the same arithmetic. At any single gas price, this model costs more per year than a median unit in its class under the test draw. The installed price range appears in its own block on this page as a modeled range, not a quote. Actual gas bills for a given home are not available from the registry.