LOCHINVAR T-H3M-OS-N 1**

The figure of 122 therms is computed by this site, not published by the registry. It starts from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.91 for this model. It then applies the daily hot-water draw the federal test assigns to the medium draw pattern. The result therefore holds only for that draw pattern. A household that draws more or less hot water than the test assumes will use a different amount of gas. The source is the DOE CCD, retrieved 2026-09-19. The registry also lists a maximum flow rate in gallons per minute of 3.5, which is a separate rating and does not enter the energy calculation.

Against its class, this unit sits 13 therms below the median of 135 therms. Its rank is 4th lowest of 80 models registered as a gas tankless unit at the medium draw pattern, which puts it in the lowest quarter of its class for energy use. That comparison helps a reader confirm where T-H3M-OS-N 1** stands among same-class models at that draw pattern. It helps less for a household whose hot-water use differs from the test's draw, because the 122 therms figure is not adjusted for other usage in this data. To compare against another unit of the same class, use the same-class replacement lookup by model number.

The running cost is not stated in the text. It depends on the state average residential gas price, so the page computes it from the reader's ZIP and gives no cost figure here. As a check, multiply 122 therms by a local gas price per therm to get a yearly amount at the medium draw pattern. The cost calculator for your own ZIP does this for you, and the annual cost methodology describes the calculation. A single rate applied to both this model and the class median of 135 therms would leave the 13 therms difference in therms unchanged. The installed price range is shown in its own block with its source and date, and it is not repeated here.