LOCHINVAR T-H3S-OS-N 1**

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.94 for this model. The registry does not publish an annual figure, so this site computed 180 therms of natural gas from that UEF and 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 only to that draw pattern, meaning a larger household, or a home where showers and laundry overlap. Energy use at any other draw pattern is not available on this page. The class median is 182 therms, so the figure alone separates this model from the median by only 2 therms. The calculation is described in how the annual cost is calculated.

Among the 397 gas tankless units registered at the high draw pattern, this model ranks 165th lowest for energy use, which places it in the second-lowest quarter of its class. The listed maximum flow rate in gallons per minute is 5.3. The temperature rise that flow rate depends on is not available in this data, so this page cannot compare it with a household's actual demand. These figures suit a reader verifying a unit for a home that matches the high draw pattern. They do not describe a home with a lighter draw, because energy use at that draw is not available here. A reader in that position can start from the water heater selector by fuel, space and size instead.

Running cost is not stated in the text because it depends on the state average residential gas price. The cost calculator on your own ZIP applies that price to the 180 therms figure for this model at the high draw pattern. If the price you pay differs from the state average, your own cost will differ from the calculated one. The modeled installed-cost range appears in its own block with its source and date. It is a modeled range, not a quote, and it is not restated here. To compare this model with others in its class, find a same-class replacement by model number using T-H3S-OS-N 1**, with the class median of 182 therms as the reference point.