RELIANCE WATER HEATERS GCB-40 4**

The registry does not list the 264 therms figure. This site computed it from two inputs. The first is the model's UEF, the ratio of hot water delivered to energy used, which the registry lists as 0.64. The second is the DOE test's daily hot-water draw for the high pattern. The source is the DOE CCD, retrieved 2026-09-19. The figure therefore describes the unit at the test's draw, not in a particular home. A household that draws more or less hot water each day than the test assumes will use a different amount of gas. That amount is not available here. The steps are set out in how the annual energy and cost figures are calculated.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. For that use, the model has a 38 gallon rated volume. Its first hour rating, the gallons of hot water available in the first hour from a full tank, is 78 gallons. Among the 414 gas tank models at the high draw pattern, it ranks 236th lowest in annual energy use. That puts it in the second-highest quarter of its class, 4 therms a year above the 260 therms class median. A reader who wants a unit below that median can find a same-class replacement by model number. A household with daily use well below the high pattern falls outside the condition this figure covers.

This text gives no running cost because the cost depends on your own gas rate. The page works it out from the 264 therms a year at the high draw pattern and your state's average residential natural gas price, found from your ZIP. You can do this with the cost calculator for your own ZIP. The 4 therms gap to the class median depends on the same state price, so no fixed cost figure can be given for it. The installed price range appears in its own block on this page, with its source and date. It is a modeled installed-cost range, not a quote, and it is not repeated here.