A. O. SMITH ATO-180B-N 1**
0.82 UEF DOE CCD · 2026-09-19Grade G: where this UEF sits among the 397 models in its class, lowest (G) to highest (A). A position, not an official label. How the grade is set
A gas tankless unit, high draw pattern (a larger household, or one where showers and laundry overlap).
If you are checking the A. O. SMITH ATO-180B-N 1**, a gas tankless unit, this site computes 206 therms of natural gas a year at the high draw pattern, the standard daily hot-water usage DOE tests against. That is 24 therms above the class median of 182 therms.
Energy use per year
206 therms a year
Computed by this site from the registry's UEF and the federal test's daily hot-water draw for this draw pattern. What it costs depends on the natural gas rate where you live.
That is above the median of 182 therms for the 397 models registered in the same heater type and draw pattern; it ranks 229 of 397, lowest energy first.
Solid line: this model (206 therms). Dashed line: the class median.
Min 173 therms Median 182 therms Max 209 therms
What it costs to run where you live
What the registry files
- UEF (Uniform Energy Factor) how much hot water you get for each unit of energy the heater uses
- 0.82 DOE CCD · 2026-09-19 Compared only with other models registered as a gas tankless unit at the high draw pattern.
- Draw Pattern the standard daily usage profile DOE tests the unit against
- High DOE CCD · 2026-09-19
- Maximum Gallons Per Minute how many gallons a minute it can heat while running continuously
- 4.7 gal/min DOE CCD · 2026-09-19
What it costs to install
$1,745–$2,687 installed
Not a quote — a modeled range of what installers have charged for this class of unit; your price will vary with labor rates, access, and local code requirements.
Escalation indexes: equipment (BLS PPI) latest available: August 2026; labor (BLS ECI) latest available: April 2026 to June 2026.
NLR REMDB (BLS PPI/ECI escalated) · 2026-04-01Safety record
No CPSC recall names this model.
Checked against the CPSC recall database. CPSC does not publish a model-level match for this product category, so this list is curated by hand from the manufacturer's recall filings.
CPSC · 2026-09-24What these figures mean
How this compares
The closest models in the same class — same fuel, type and draw pattern.
Keep going
How every figure on this page is calculated
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What a water heater costs to run
Prices a unit's efficiency against your own utility's filed tariff for your ZIP code.
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How to size a tankless water heater by GPM
Answered from what models in this size actually file.
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Water heaters
Every model on file with the Department of Energy, by heater type.
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All gas tankless water heaters
Gas-fired instantaneous units, sized by flow rate rather than tank gallons.
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Every A. O. SMITH model on file
What this brand files, by heater type.
UEF 0.82 · Grade G Price it on your ZIP
The registry lists a UEF of 0.82 for this model. UEF, the ratio of hot water delivered to energy used, is the input to the annual figure. The registry does not publish the annual energy itself. This site computed 206 therms by combining the registry's UEF with the DOE test's daily hot-water draw for the high draw pattern. The source is DOE CCD, retrieved 2026-09-19. Among the 397 models registered as a gas tankless unit at the high draw pattern, this one ranks 229th lowest for energy use. It sits in the second-highest quarter of its class, 24 therms above the class median of 182 therms. The figure is a test-condition value, not a reading from an installed unit.
The high draw pattern describes a larger household, or one where showers and laundry overlap. The 206 therms figure applies only to that pattern. A household with lighter use is not described by it, and no figure for other draw patterns is available on this page. The registry lists a maximum flow rate in gallons per minute of 4.7 for this model. The data does not say how many fixtures that flow supports at once, so this page does not estimate it. The 24 therms difference from the class median of 182 therms applies to this pattern only. To filter by fuel, space and size, use the water heater selector, or find a same-class replacement by model number.
Running cost is not stated in this text because it depends on the state average residential gas price, which differs by reader. It follows from the 206 therms of natural gas multiplied by that price. The cost calculator applies the price for your ZIP to this model's figure. The steps are set out in how the annual cost is calculated. Any result carries the conditions of the energy figure: the high draw pattern, the federal test's daily hot-water draw, and the UEF of 0.82. Actual use in a home can differ, and the data here does not say by how much. The installed-cost range appears in its own block with its source and date, as a modeled range and not a quote, so it is not restated here.
DOE CCD · 2026-09-19