Westinghouse HS120

This site computed 134 therms from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.83 for this model. It then applied the daily hot-water draw that DOE uses for the medium draw pattern. The registry does not publish this annual figure itself. It is a calculation, and it holds only at that test draw. The source is the DOE CCD, retrieved 2026-09-19. Real use in a home will differ with the household's actual hot-water demand and inlet water temperature. Neither is in the registry data. The method is set out in how the annual cost is calculated.

The unit sits 1 therms below the class median of 135 therms. That gap is small next to the median, so the unit is near the typical figure for its class. It ranks 28th lowest of 80 gas tankless models at the medium draw pattern, which is the second-lowest quarter of its class for energy use. The registry lists a maximum flow rate in gallons per minute of 3.3. That is a flow limit, not a measure of energy use. The 134 therms figure suits a household whose demand is close to the medium draw pattern. A household with much higher demand should not read it as its own use. This page does not estimate that higher figure.

Running cost depends on the average residential natural gas price in your state, so no cost is written here. To check it, multiply 134 therms by your own price per therm. The cost calculator on your own ZIP does this for you. Either result holds only at the medium draw pattern and the UEF of 0.83. The modeled installed-cost range for the HS120 appears in its own block with its source and date. It is a modeled range, not a quote. To compare against other units, look up a same-class replacement by model number.