LOCHINVAR TK-310C-NI 1**

UEF, the ratio of hot water delivered to energy used, is 0.81 for this model. The registry does not list annual energy directly. This site computed 209 therms from that UEF and the DOE test's daily hot-water draw for the high draw pattern, which describes a larger household, or one where showers and laundry overlap. The unit ranks 323rd lowest energy use of 397, and its figure sits 27 therms above the class median of 182 therms. The source is DOE CCD, retrieved 2026-09-19. The figure applies only to that test draw, not to a measured home.

The maximum flow rate in gallons per minute is 4.6. The registry data used here does not say whether that flow meets the needs of a particular home, so this page makes no such claim. The energy figure fits households that resemble the high draw pattern, because the test was run at that draw. It is a weaker reference for a home with lighter use, and annual energy at other draw patterns is not available on this page. Anyone whose main aim is the lowest gas use in the class should note the 323rd lowest rank of 397. To compare by fuel, space and size, use the water heater selector, or look up a same-class replacement 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 the price per therm in your area gives an estimate at the test draw, and your own household's draw will move the result. The cost calculator applies the price for your ZIP, and the calculation method explains how the annual cost is worked out. The modeled installed-cost range is shown in its own block with its source and date. It is a modeled range, not a quote, and it is not repeated in this text. The class median of 182 therms is the reference point for any comparison with other models.