ENVO WH-AZ52-199-NGO

The figure of 209 therms 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, of 0.81 with the DOE test's daily hot-water draw for the high draw pattern. The source is DOE CCD, retrieved 2026-09-19. The figure applies to natural gas at that test draw only. It is a computed annual figure, not a metered reading from an installed unit. A household that draws more or less hot water than the test will use a different amount, and this page has no data on that. The method behind the annual figures is documented separately.

Among the 397 models registered as a gas tankless unit at the high draw pattern, this unit sits 27 therms above the class median of 182 therms. It ranks 323rd lowest energy use of 397, which puts it in the highest quarter of its class for energy use. The high draw pattern describes a larger household, or one where showers and laundry overlap. The registry lists a maximum flow rate in gallons per minute of 4.8. A reader who wants the lowest gas use at this draw should look at models with a lower rank number, since those use less at the same test draw. The same-class replacement search finds those models by model number.

The running cost is not stated here because it depends on your state's average residential gas price. Multiplying 209 therms by your own rate per therm gives the yearly gas cost at the test draw. The same arithmetic applied to the 27 therms gap above the class median of 182 therms gives the yearly cost of that gap. Enter your ZIP in the cost calculator to see both on your local rate. Actual use in a home is not known from the registry, because it depends on the household's real hot-water draw. The modeled installed-cost range is shown in its own block on this page, with its source and date.