Fogatti FDG420IN-CS120-NG

The federal test rates this unit at 135 therms of natural gas a year at the medium draw pattern, which stands for a typical household on a busy morning. This site computed that figure from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.82, and the DOE test's daily hot-water draw for that pattern. The registry does not publish the annual figure itself. The source is the DOE CCD, retrieved 2026-09-19. The registry also lists a maximum flow rate in gallons per minute of 2.9. That flow rating is a separate specification and does not change the annual energy figure.

Against its class, the unit ranks 32nd lowest in energy use of 80 models registered as a gas tankless unit at the medium draw pattern. That places it in the second-lowest quarter of its class. Its 135 therms sits exactly at the class median of 135 therms, so the difference is 0 therms. The figure suits a reader who wants to check this unit against its peers for a household whose hot-water use resembles the medium draw pattern. It says less about households whose daily use differs from that pattern, because the registry gives no figure for other draws. To compare other units, use the water heater selector or find a same-class replacement by model number.

The running cost is not stated in this text because it depends on the state average residential gas price, which differs by reader. Multiplying 135 therms by your own rate gives a cost at the medium draw pattern only, not a forecast of your bill. The cost calculator does this from your ZIP, and the methodology page explains how the annual cost is calculated. The modeled installed-cost range appears in its own block on this page with its source and date. It is a modeled range, not a quote. Your household's actual hot-water use and the gas rate you pay are not in this data, so they are unknown here.