Ruud RTGH-68DVLN-3

The 123 therms figure is calculated by this site, not taken from the registry. It 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 medium pattern. The registry lists a UEF of 0.9 for this model, taken from the DOE Compliance Certification Database on 2026-09-19. The result repeats the test day across a year, so it does not describe metered use in any one home. A household that uses more or less hot water than the medium pattern will use a different amount of gas. The steps behind this conversion are set out on the page that explains how the annual cost is calculated.

Among the 80 gas tankless units registered at the medium draw pattern, this model ranks 10th for lowest energy use. That places it in the lowest quarter of its class. The 12 therms gap below the median applies only at the medium pattern's test draw. The registry also lists a maximum flow rate in gallons per minute of 3.5 for this unit. That rating shows how much hot water it can deliver at one time, and the annual figure does not show this. A home whose peak simultaneous demand exceeds 3.5 gallons per minute needs more flow than this unit is rated for. To see other models in the same class, use the same-class replacement lookup by model number.

The running cost is not given in this text. The cost of 123 therms of natural gas a year depends on your state's average residential gas price, and this page does not estimate it. The page calculates the cost from your ZIP instead. Readers in different states who own this model and use hot water at the medium pattern can see different yearly costs. Likewise, the 12 therms gap to the class median becomes a different cost gap on each state's rate. To see the figure for your own rate, enter your ZIP in the water heater cost calculator. The installed price range on this page is a modeled range, not a quote, and its source and date appear in that block.