ENVO WH-AZ03-180-LPI

The annual figure of 197 therms is not read from the registry. The registry lists this model's UEF, the ratio of hot water delivered to energy used, as 0.86. This site combines that UEF with the DOE test's daily hot-water draw for the high draw pattern. The data source is DOE CCD, retrieved 2026-09-19. The figure applies only at that test draw, so a household with a different draw will use a different amount. The methodology page explains how the annual cost is calculated.

Against its class, this model sits 15 therms above the median of 182 therms. The comparison covers 397 models registered as a gas tankless unit at the high draw pattern. Its rank is 226th lowest energy use of 397, in the second-highest quarter of its class for energy use. A lower rank number means less energy at the same test draw. The rank compares registry entries only and does not measure hot-water output at the tap. This page does not show the gap at other draw patterns. To look for a same-class alternative, the replacement finder works from a model number.

The high draw pattern describes a larger household, or one where showers and laundry overlap. For that use, the figure to compare is 197 therms. The registry lists the maximum flow rate in gallons per minute as 4.3, a separate measure from annual energy use. A reader whose priority is low gas use should note the 15 therms gap to the class median. A household that draws less hot water than the test will use fewer therms, and this page cannot say how many. Running cost depends on your state's average residential gas price, so no cost is written in the text. The cost calculator applies that price from your ZIP to 197 therms.