LOCHINVAR TK-110U-I 2**

The 137 therms figure is not a registry value. This site computed it from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.81 for this model, and from the daily hot-water draw the DOE test assigns to the medium draw pattern. The source is DOE CCD, retrieved 2026-09-19. The unit's maximum flow rate in gallons per minute is listed at 3.5, a separate rating that does not enter the energy calculation. The figure holds only at that test draw. A household that uses more or less hot water will use a different amount of gas, and this data does not show by how much.

Among the 80 models registered as a gas tankless unit at the medium draw pattern, this unit uses 2 therms more than the class median of 135 therms. Its rank is 52nd lowest energy use of 80, which places it in the second-highest quarter of its class for energy use. That suits a reader who needs a gas tankless unit and accepts use above the class median. It does not suit a reader whose priority is the lowest gas use in the class, because models ranked ahead of it use less at the same draw pattern. To compare other units, the water heater selector filters by fuel, space and size, and the same-class replacement finder works from a model number.

The running cost is not written here because it depends on your state's average residential gas price, and this page does not assume one. Multiply the 137 therms by your own price per therm, or enter your ZIP in the cost calculator, which does this for you. The method behind the annual cost lists the steps. Two limits apply. The figure is valid only at the medium draw pattern, and it is derived from a UEF of 0.81, not measured in your home. Gas use for a household with different hot-water habits is not available from this data. The installed-cost range appears in its own block, with its source and date.