RELIANCE WATER HEATERS T-H3S-OS-N 1**

This site computes the 180 therms figure; the registry does not publish it. The figure combines the registry's UEF, the ratio of hot water delivered to energy used, with the daily hot-water draw that the DOE test sets for the high draw pattern. The registry lists this model's UEF as 0.94. The source is the DOE CCD, retrieved 2026-09-19. Because the figure uses the test's daily draw, it describes the test household, not a measured home. A home that draws more or less hot water than the test will use a different amount of gas, and that amount is not in this data. The steps from this figure to a yearly cost are set out in how the annual cost is calculated.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. This unit ranks 165th lowest in energy use among the 397 models registered as a gas tankless unit at that pattern. That rank places it in the second-lowest quarter of its class for energy use, not the lowest quarter. The registry also lists a maximum flow rate in gallons per minute of 5.3. The data do not show how that flow matches the fixtures in a given home. To see other units side by side by fuel, space and size, use the water heater selector by fuel, space and size.

The 180 therms figure holds only at the high draw pattern. A smaller household with a lower daily draw falls outside that condition. A figure for this model at other draw patterns is not available in this data. The page text states no running cost, because the cost depends on the reader's state average residential gas price. The page computes it from the reader's ZIP, using the 180 therms figure at the high draw pattern. You can check it in the cost calculator on your own ZIP. The installed price range sits in its own block, with its source and date. It is a modeled installed-cost range, not a quote.