AMERICAN TK-310CX3 1**

The registry lists a UEF of 0.81, the ratio of hot water delivered to energy used, and a maximum flow rate in gallons per minute of 4.7. The annual figure of 209 therms was computed by this site, not the registry. It combines the registry UEF with the DOE test's daily hot-water draw for the high draw pattern. The figure applies only to natural gas and to that draw, and the DOE CCD data was retrieved on 2026-09-19. A home that uses more or less hot water than the test assumes will use a different amount. Measured use in an individual home is not available from the registry. The steps behind the calculation are set out in how the annual cost is calculated.

The unit is compared with the 397 models registered as a gas tankless unit at the high draw pattern. It ranks 323rd lowest energy use of 397, which places it in the highest quarter of its class for energy use. Its 209 therms sits 27 therms above the class median of 182 therms. The high draw pattern describes a larger household, or one where showers and laundry overlap, so the figure fits readers whose use matches that description. It fits less well for a reader who wants energy use at or below the median, since models ranked lower than 323rd use less at this draw. The comparison covers only this fuel and draw pattern. A selector by fuel, space and size can narrow the options.

The running cost is not stated in the text because it depends on the state average residential gas price where you live. The cost calculator on your own ZIP applies that price to the 209 therms figure. The same 209 therms costs more or less as the price changes, and the 27 therms gap to the class median of 182 therms scales with it. The modeled installed-cost range sits in its own block on this page with its source and date. It is a modeled range, not a quote, so it is not repeated here. To compare against another unit of the same class, you can find a same-class replacement by model number.