Ruud RTG-84XLN-1

This site calculates the 209 therms figure; the registry does not publish it. It combines the model'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. For this model, the registry lists a UEF of 0.81. The source is DOE CCD, retrieved 2026-09-19. The class has 397 models registered as gas tankless units at the high draw pattern. This model ranks 323rd for lowest energy use. That places it in the highest quarter of its class for energy use. The steps behind this figure are set out in how the annual energy and cost are calculated.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. The 209 therms estimate holds only for that test draw. A household that draws less hot water each day would use a different amount of gas. This page does not have that figure. The registry lists this model's maximum flow rate in gallons per minute as 4.5. Whether that rate covers several outlets running at once depends on the fixtures in the home, and the registry does not record them. If you are checking other models by fuel, space and size, use the water heater selector by fuel, space and size.

The running cost of 209 therms a year depends on your state's average residential gas price. For that reason, this text does not state a cost. The page works it out from your ZIP in the running cost calculator for your own ZIP. This model's gas use at the high draw pattern is above the class median, as described earlier. The cost of that gap depends on your local gas rate. If you are checking an existing unit against others in its class, the same-class replacement search by model number lists other gas tankless units at the high draw pattern. The installed-cost range on this page has its own block, with its source and date. It is a modeled range, not a quote.