A. O. SMITH GCBL-30R 4**

The registry lists this model's UEF, the ratio of hot water delivered to energy used, at 0.6. This site computed 185 therms a year from that UEF and the DOE test's daily hot-water draw. The registry does not publish the annual figure itself. The figure applies to the medium draw pattern and comes from DOE CCD, retrieved 2026-09-19. The class median is 185 therms, so this model sits 0 therms from it. It uses the same gas as the median model in its class. It ranks 89th lowest for energy use among 288 models registered as a gas tank at this draw pattern.

The first hour rating, the gallons of hot water available in the first hour from a full tank, is 65 gallons. The rated volume is 29 gallons. The energy figure assumes the medium draw pattern, which describes a typical household on a busy morning. A household with a similar pattern can compare 185 therms with the class median directly. A household that draws much more hot water should not rely on that figure. Its annual use at a heavier draw is not available here. The same applies to a lighter draw, because the registry data used here does not cover it.

The running cost depends on your state's average residential gas price, so this page states no cost. The cost calculator applies the price for your ZIP to 185 therms. How the annual cost is calculated is set out on the methodology page. The installed price range is not published. This model's ratings, 65 gallons first hour rating and 29 gallons rated volume, lie outside the range the cost database's model was fitted on. That range is not stretched past its limit. To compare other options, use the water heater selector by fuel, space and size, or find a same-class replacement by model number.