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

The 206 therms figure comes from this site's calculation. The registry does not publish it. The calculation uses the registry's UEF, the ratio of hot water delivered to energy used, and the daily hot-water draw from the DOE test for the high pattern. For this model the UEF is 0.82, taken from DOE CCD data retrieved 2026-09-19. The result applies only at that test draw. The registry has no record of use in real homes, so the gas this unit burns at any other daily draw is not available here. Each step is set out in how this site calculates annual energy and cost. You can use that page to check the figure against the registry's UEF yourself.

In plain terms, 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. That is the rated figure, and the flow a given home gets is not recorded. The class used for comparison contains only the 397 models registered as a gas tankless unit at the high pattern. Within that class, the rank stated above puts this model in the second-highest quarter for energy use. If you are checking a replacement quote, keep the comparison to models tested at the same pattern. You can find a same-class replacement by model number and compare those models on the same basis.

The 24 therms gap works out as follows: at the same test draw, the median model in this class uses 182 therms, while this unit uses 206 therms. If lower gas use is your main test, other models registered in the class use less. Its figure at a lower draw pattern is not available on this page, so a smaller household cannot read its own use from these numbers. The running cost is not stated here. It depends on your state's average residential gas price. The cost calculator for your own ZIP turns 206 therms into a yearly cost at that rate. The installed-price range appears in its own block, with its source and date. It is a modeled range, not a quote.