Fogatti FDG420OD-CS120S-NG

The figure of 135 therms 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, which is 0.82 for this model, with the daily hot-water draw that the DOE test assigns to the medium draw pattern. The source is the DOE CCD, retrieved 2026-09-19. The figure holds for natural gas and for the test's daily draw only. A home that draws more or less hot water than the test will use a different amount, and the registry does not provide measured use for any single home.

Among the 80 models registered as a gas tankless unit at the medium draw pattern, this model ranks 32nd lowest in energy use of 80. That places it in the second-lowest quarter of its class. Its 135 therms equals the class median of 135 therms, so the difference is 0 therms. The maximum flow rate in gallons per minute is 2.9; this is a separate rated value and does not enter the energy figure. The comparison applies only to units of the same type, fuel and draw pattern. It suits a reader confirming where this entry sits within its class. It does not cover tank or electric models. For a unit in the same class, use find a same-class replacement by model number.

Running cost is not stated here because it depends on the state average residential gas price, which differs by reader. To estimate it, multiply 135 therms by your own price per therm, or enter your ZIP in the cost calculator that uses your ZIP. The result applies only to the medium draw pattern; a different draw changes the therms and therefore the cost. The method behind the annual cost calculation sets out the inputs. The installed-cost range on this page is shown in its own block with its source and date. It is a modeled range, not a quote.