LOCHINVAR TK-510U-I 2**

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.81 for this unit. This site then combined that UEF with the DOE test's daily hot-water draw to reach 209 therms. The registry does not publish that annual figure itself. It applies to natural gas at the high draw pattern only. The registry also lists a maximum flow rate in gallons per minute of 5. The data does not show how the unit performs at any other draw pattern, so this page does not estimate it. The energy figure comes from DOE CCD, retrieved 2026-09-19.

The high draw pattern describes a larger household, or one where showers and laundry overlap. Its rank is 323rd lowest energy use of 397 models in its class. That 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. A household with lighter use is outside this figure, because the data covers the high draw pattern only. To compare by fuel, space and size, use the water heater selector. If you need a same-class alternative, you can look up a replacement by model number.

Running cost is not stated in the text because it depends on your state's average residential gas price. Multiplying 209 therms by your own gas rate gives the yearly cost at this draw pattern. The cost calculator does this from your ZIP code. The methodology page explains how the annual cost is calculated. At the same gas rate, 27 therms above the median means a higher yearly cost than the median model. The installed price range appears in its own block, with its source and date. The registry does not state your local rate, so no cost is estimated here.