LOCHINVAR ATO-180B-N 1**

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.82 for this unit. This site computed 206 therms of natural gas from that UEF and the DOE test's daily hot-water draw for the high draw pattern. The registry does not publish the annual figure itself. The unit ranks 229th lowest in energy use among 397 models, which places it in the second-highest quarter of its class for energy use. Its figure sits 24 therms above the class median of 182 therms. The comparison covers only gas tankless models at the high draw pattern. The source is DOE CCD, retrieved on 2026-09-19.

The high draw pattern describes a larger household, or one where showers and laundry overlap. This unit's energy figure of 206 therms applies to that pattern only. A smaller household falls under a different draw pattern, and this figure would not carry over to it. The rated maximum flow rate in gallons per minute is 4.7. The registry data here does not include the temperature rise that flow rate depends on, so that value is not available. Some readers want energy use at or below the class median of 182 therms. This unit sits 24 therms above it. To compare other models, use the selector by fuel, space and size or find a same-class replacement by model number.

The running cost is not stated in the text. It depends on your state's average residential gas price. The cost calculator on your own ZIP applies that price to the 206 therms shown here. How the annual cost is calculated is described on the methodology page. At the same gas price, this unit costs more to run than a model using the class median of 182 therms. The annual figure belongs to the high draw pattern, so a different household pattern changes the cost. The installed price appears in its own block with its source and date. It is a modeled installed-cost range, not a quote, and this text does not repeat it.