Noritz EZ98DV (GQ-C2861WX-FF US)

The registry does not print the 173 therms figure. This site computes it from the model's UEF, the ratio of hot water delivered to energy used, which is 0.98. It combines that with the DOE test's daily hot-water draw for the high draw pattern. The source is the DOE CCD, retrieved 2026-09-19. The figure therefore holds only at that test draw. A home that uses more hot water each day will burn more gas than 173 therms, and one that uses less will burn less. That difference is not available here, because actual household use is not in the data. Among the 397 registered gas tankless models at the high draw pattern, this model ranks 1st lowest in energy use. The page on how the annual cost is calculated sets out the steps.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. The 173 therms figure describes that kind of use, and so does the 182 therms class median. A household of that kind can read the 9 therms gap below the median directly. The registry also lists a maximum flow rate in gallons per minute of 5.3 for this model. A home whose fixtures, running together, need more than 5.3 gallons per minute falls outside that rating. A smaller household with separate showers and laundry uses less than the test draw, so its yearly use is not the 173 therms shown. Its own figure is not available here. Readers comparing other fuels, spaces or sizes can use the water heater selector by fuel, space and size.

This text does not state the running cost. It depends on the reader's state average residential gas price, so the page calculates it from the reader's ZIP code. It uses the same 173 therms of natural gas at the high draw pattern. The 9 therms gap to the class median turns into a cost gap only at that same rate. For that reason, this text does not give the gap as a cost either. To see the cost at your own rate, use the cost calculator for your ZIP code. The installed-price range appears in its own block on this page, with its source and date. It is a modeled installed-cost range, not a quote, and this text does not repeat its figures.