STATE T-H3S-OS-N 1**

This site calculates the 180 therms figure; the registry does not publish it. The calculation uses the model's UEF, the ratio of hot water delivered to energy used, which is 0.94 for this unit. It also uses the DOE test's daily hot-water draw for the high draw pattern. Both inputs come from the DOE Compliance Certification Database, retrieved 2026-09-19. The figure holds only at that test draw. A household that uses more or less hot water than the test assumes will use a different amount of gas. The registry data does not show a given household's actual use, so that amount is not available here. The page on how the annual figure is calculated explains each step.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. The 180 therms figure describes that level of use. It does not describe a household with lighter hot-water use than the pattern assumes. The registry lists a maximum flow rate in gallons per minute of 5.3 for this model. That is the limit on hot water delivered at once. Whether it covers a given set of fixtures depends on their flow rates, which this data does not include. Among the 397 models in its class, this unit is 2 therms below the median. That puts it below the median, but it is not one of the class's lowest-use models. To compare other units, use the selector by fuel, space and size.

Running cost is not stated in this text. It depends on the average residential natural gas price in your state. The page works it out from your ZIP code and the 180 therms test figure. The cost calculator for your own ZIP runs the same calculation. At any gas price, this model's cost differs from the class median cost only by the cost of 2 therms of gas a year. The installed price range on this page is a modeled installed-cost range, not a quote. Its source and date appear in its own block. If you need a unit in the same class as the T-H3S-OS-N 1**, you can find a same-class replacement by model number.