RINNAI (RUCS75I) REU-KCM2528FFU-US

This site calculated the 188 therms figure. The registry does not list it. 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. This model's UEF is 0.9. The result is valid only at the federal test's daily draw. It does not describe how much gas any particular home uses. The inputs come from the DOE CCD, retrieved 2026-09-19. A plumber or seller who wants to check the number can follow each step in how this site calculates annual energy and cost. This page shows no figure for this model at any other draw pattern, so that value is not available here.

The high draw pattern represents a larger household, or one where showers and laundry overlap. The 188 therms figure is based on that level of use. The comparison class is the 397 models registered as a gas tankless unit at the high draw pattern. This model ranks 218th for lowest energy use of 397, which puts it above the median, as the summary notes. Its maximum flow rate in gallons per minute is 4.5. A smaller household does not match the test condition behind 188 therms, and this page has no figure for a lower pattern. Readers looking for a unit nearer to or below the 182 therms median can find a same-class replacement by model number.

This text gives no running cost. The cost depends on the reader's state average residential gas price, so the page calculates it from the reader's ZIP. That rate is applied to 188 therms a year at the high draw pattern. The 6 therms gap to the class median is priced at the same rate, so its cost also depends on the reader's state. To see the yearly figure, enter a ZIP in the running cost calculator for your own ZIP. The installed price appears in its own block with its source and date. It is a modeled range, not a quote. Two things are unknown here: how much hot water any single home uses, and the gas price a given utility actually charges.