ENVO WH-AZ54-199-LPO

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.87 for this model. This site computed the annual figure of 195 therms from that UEF and the DOE test's daily hot-water draw for the high draw pattern. The registry does not publish the annual figure itself. It covers natural gas only and comes from the DOE CCD, retrieved 2026-09-19. Because it rests on the test's draw, a household that uses more or less hot water than the test will see a different result. The maximum flow rate in gallons per minute is 5. That is a separate rating and does not say how much gas the unit uses in a year. The methodology page explains how the calculation is done.

The comparison class is the 397 models registered as a gas tankless unit at the high draw pattern. At 195 therms, this model sits 13 therms above the class median of 182 therms. Its rank is 225th lowest energy use of 397, which places it in the second-highest quarter of its class for energy use. The high draw pattern describes a larger household, or one where showers and laundry overlap, so the figure is most relevant to that kind of use. For a household with lighter use, the 195 therms figure does not apply, and this page shows no figure for other draw patterns. To compare against other units in the same class, the same-class replacement search works from a model number.

The running cost is not stated in this text. It depends on the state average residential gas price, and that price is not in the data for this page, so no cost is estimated here. To see the cost of 195 therms of natural gas at your own rate, use the cost calculator, which works from your ZIP. The installed price range appears in its own block on this page as a modeled installed-cost range, not a quote, with its source and date. If the 13 therms gap above the class median of 182 therms matters for your choice, the selector by fuel, space and size narrows models on those three inputs.