AMERICAN TK-110U-E 2**

The registry lists this model with a UEF, the ratio of hot water delivered to energy used, of 0.81. This site computed the annual figure of 137 therms from that UEF and the DOE test's daily hot-water draw for the medium draw pattern. The registry itself does not publish an annual energy figure. The data comes from the DOE CCD, retrieved 2026-09-19. The comparison group is the 80 models registered as a gas tankless unit at the medium draw pattern. This model ranks 52nd lowest in energy use within that group. Its use is 2 therms above the class median of 135 therms, so it sits above the middle of its class for energy use.

The 137 therms applies only to the medium draw pattern, which the data describes as a typical household on a busy morning. It suits a check for households whose use matches that pattern. It does not describe a household with much more or much less hot-water use, and this page does not estimate that case. The registered maximum flow rate in gallons per minute is 3.5. That value is a flow limit, not an energy measure, and the data here does not state the temperature rise at which it applies. To compare against units of the same class, use the selector by fuel, space and size or find a same-class replacement by model number.

The running cost is not written in this text because it depends on your state's average residential gas price. The cost calculator on your own ZIP applies that price to the 137 therms shown here. How the annual cost is calculated is documented separately. Any cost result carries the same condition as the energy figure: the medium draw pattern and the federal test's daily draw. The figure is a calculation from registry data, not a measurement of an installed unit, so a gas meter reading in a home may differ from it. The modeled installed-cost range appears in its own block with its source and date. It is a modeled range, not a quote, and is not restated here.