ORBEK HW080

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.81 for the ORBEK HW080. It does not publish an annual figure. This site computed 95 therms from that UEF and the DOE test's daily hot-water draw for the low draw pattern, using the DOE CCD data retrieved on 2026-09-19. The figure is therefore a test-condition value for natural gas, not a measurement from a home. Against the 10 models registered as a gas tankless unit at this draw pattern, it ranks 7th lowest in energy use. That places it in the second-highest quarter of its class, 2 therms above the 93 therms median. The steps behind the calculation are set out in the methodology for water heater cost.

The low draw pattern describes a small household, and the 95 therms figure applies only at that draw. The registry lists a maximum flow rate in gallons per minute of 2.1 for this model. The unit suits a reader whose hot-water use resembles the test draw and who wants to confirm the registry entry. It does not describe a household with heavier use: the data for this page holds no figure for other draw patterns, so energy use at those draws is not available here. A gap of 2 therms from the 93 therms class median is what the registry data shows, and it says nothing about the model outside these test conditions. To compare fuel, space and size, the water heater selector covers those inputs.

The running cost is not written in this text, because it depends on the average residential gas price in your state. Multiplying 95 therms by your own gas rate gives the test-condition cost, and the cost calculator does this from your ZIP. Actual bills will differ if your household's draw differs from the low draw pattern. 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, and this text does not restate it. If you need a unit in the same class as the HW080, the same-class replacement finder searches by model number.