Ruud SFT 199-1

The 188 therms figure is computed by this site, not published by the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, with the DOE test's daily hot-water draw for the high pattern. The registry lists a UEF of 0.9 for the Ruud SFT 199-1. The source is the DOE CCD, retrieved 2026-09-19. The result holds only at the test's daily draw. A household that draws more or less hot water than the test will use a different amount of gas, and that amount is not available here. The steps behind the figure are set out on the page on how the annual cost is calculated.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. That is the use the 188 therms figure describes. The registry lists this unit's maximum flow rate in gallons per minute as 5.3. Among the 397 models registered as a gas tankless unit at the high draw pattern, it ranks 218th for lowest energy use. The gap to the class median is 6 therms a year at the test's draw. A home that fits the high pattern can compare these figures directly. A home with lower daily use belongs to a different draw pattern, and this figure does not describe it. To compare models in the same class, use the same-class replacement search by model number.

This page does not state a running cost in the text. The cost depends on your state's average residential gas price, so the page computes it from your ZIP. That rate, applied to 188 therms a year at the high draw pattern, gives the cost for this model. The same rate, applied to the 182 therms class median, shows what the 6 therms gap means at your price. Both results assume the test's daily hot-water draw, not your household's measured use. You can run the figures in the cost calculator for your own ZIP. The installed price shown in its own block is a modeled range with its source and date, not a quote.