Ruud PROG30S-30N RH63

The 185 therms figure is calculated by this site. The registry does not publish it. It combines the model's UEF, the ratio of hot water delivered to energy used, with the DOE test's daily hot-water draw for the medium draw pattern. The registry lists a UEF of 0.6 for this model in the DOE Compliance Certification Database, retrieved 2026-09-19. The result applies only at that test draw. A household that uses more or less hot water each day will use a different amount of gas, and that amount is not available here. The page on how the annual energy and cost are calculated explains each step.

Among the 288 models registered as a gas tank at the medium draw pattern, this model ranks 89th lowest for energy use. That puts it in the second-lowest quarter of the class, even though its energy use equals the class median, as stated above. The tank has a rated volume of 29 gallons. Its first hour rating, the gallons of hot water available in the first hour from a full tank, is 51 gallons. A household whose busiest hour needs no more than 51 gallons is within this rating. A household that needs more hot water in that hour exceeds it, and this page has no energy figure for that use. The selector by fuel, space and size filters models by these ratings.

The running cost is not stated in this text. It depends on your state's average residential natural gas price. The page applies that price to the 185 therms figure once you enter your ZIP code, and the cost calculator on your own ZIP gives the same result. Two tanks with the same UEF of 0.6 can therefore cost different amounts to run in different states. An installed price range for this model is not published. Its ratings lie outside the range the cost database's model was fitted on, and the range is not stretched past it. To check other gas tanks in this class, use the same-class replacement search by model number.