NAVIEN NHW700-199AE-NG

The 209 therms figure is computed by this site, not published by 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 0.81, taken from the DOE CCD as retrieved on 2026-09-19. The result holds only at that test draw. A household using more or less hot water will use a different amount of gas. This model's maximum flow rate in gallons per minute is 5. That rating describes flow capacity and is not part of the annual energy calculation. The page on how the annual cost is calculated sets out each step.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. This model is compared with the 397 models registered as a gas tankless unit at that same draw pattern. Its 27 therms gap above the class median places it in the highest quarter of its class for energy use. A reader who wants lower gas use at this draw pattern will find most registered models in the class below it. A same-class replacement search by model number lists those models. For a household using less hot water than the high pattern assumes, the 209 therms figure does not apply directly.

The running cost is not stated in this text. It depends on your state's average residential gas price, so the page computes it from your ZIP. At 209 therms a year, the cost moves with that price: a higher state rate raises it, and a lower one reduces it. Enter your ZIP in the water heater cost calculator for your own ZIP to see the figure. The installed price range appears in its own block as a modeled installed-cost range, not a quote, with its own source and date. Neither the running cost nor that range changes the energy figure. That figure stays tied to the high draw pattern and the 0.81 UEF.