Westinghouse HW120

The 132 therms figure is not listed in the registry. This site computes it from the registry's UEF, the ratio of hot water delivered to energy used, of 0.84 and the DOE test's daily hot-water draw for the medium draw pattern. The source is DOE CCD, retrieved 2026-09-19. The result applies only to natural gas at that draw pattern. Among the 80 models registered as a gas tankless unit at the medium draw pattern, this one ranks 23rd lowest lowest in energy use, in the second-lowest quarter of its class. The class median is 135 therms, so this model sits 3 therms below it. The method behind the annual figure is set out on the methodology page.

The figure suits a reader whose household hot-water use resembles the medium draw pattern, because the 132 therms belongs to that pattern alone. The registry lists a maximum flow rate in gallons per minute of 3 for this unit. That limit is separate from annual energy and does not change the computed figure. The figure does not suit a reader with a much different daily draw, because actual gas use then departs from the tested value; this page has no data on by how much. The energy figure differs from the class median of 135 therms by 3 therms, and no other difference is stated here. To compare by fuel, space and size, use the water heater selector.

Running cost is not stated in this text because it depends on your state's average residential gas price, which this page does not assume. Multiplying 132 therms by your local price per therm gives the yearly cost at the medium draw pattern. The cost calculator on your own ZIP does this for you. 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. To look at another unit of the same class, find a same-class replacement by model number starting from HW120. Actual bills also depend on your real hot-water use, which is not available in this data.