LOCHINVAR T-H3-OS-N 1**

The annual figure of 178 therms is computed by this site, not taken from the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 0.95 with the DOE test's daily hot-water draw for the high draw pattern. The source is DOE CCD, retrieved 2026-09-19. The figure applies to natural gas and to that test draw only. Real consumption in a home depends on how much hot water the household uses, and that is not available in this data. The registry also lists a maximum flow rate in gallons per minute of 5.8, which is a capacity rating and does not enter the energy calculation.

Among 397 models registered as a gas tankless unit at the high draw pattern, this model has the 45th lowest energy use, which places it in the lowest quarter of its class. The class median is 182 therms, and this model sits 4 therms below it. A high draw pattern describes a larger household, or one where showers and laundry overlap, so the figure is most relevant to a household like that. It says less about a household whose daily draw differs from the test draw. Such a household can start from the water heater selector by fuel, space and size. Rank and median come from registered models only; how the unit performs in a given home is not available.

The running cost is not stated in the text because it depends on the state average residential gas price. The page computes it from the reader's ZIP, so 178 therms is converted at the reader's own rate and not at an estimated one. The cost calculator for your own ZIP shows that result, and the method behind the annual cost lists the steps. To compare this model with others in the same class, use the same-class replacement search by model number. A modeled installed-cost range appears in its own block on the page with its source and date. It is a range, not a quote, and its figures are not repeated here.