STATE TK-310C-NI 1**

The 209 therms figure does not appear in the registry itself. This site computed it from the model's UEF, the ratio of hot water delivered to energy used, which the registry lists at 0.81. The second input is the DOE test's daily hot-water draw for the high draw pattern. The input data come from DOE CCD, retrieved 2026-09-19. The result holds at that test draw only. A home that draws more or less hot water than the test assumes will use a different amount, and this page does not have that amount. Among the 397 gas tankless models registered at the high draw pattern, the 27 therms gap places this unit in the highest quarter of its class for energy use. The steps are set out in how the annual energy and cost are calculated.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. The 209 therms figure therefore describes that kind of use, not a smaller household's. A figure for a lower draw pattern is not available for this model on this page. Hot water at the tap also depends on flow, and the registry lists a maximum flow rate in gallons per minute of 4.6. The registry does not say how many fixtures that flow can serve at once, so that remains unknown here. The 323rd rank given above means most same-class models use less gas at the same test draw. To check those models, find a same-class replacement by model number.

No running cost is stated in this text, because it depends on your own gas rate. Turning 209 therms into a yearly bill needs your state's average residential natural gas price. The page takes that price from your ZIP, and the cost calculator for your own ZIP applies it to the same high draw pattern figure. At any single gas price, the cost gap to a median unit in this class follows the 27 therms difference directly. Actual bills will differ from that result when household use differs from the test draw. The installed-cost block elsewhere on this page is a modeled range, not a quote, and it shows its own source and date.