A. O. SMITH ATO-199B-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 this unit's energy figure, the A. O. SMITH ATO-199B-N 1**, a gas tankless unit, uses 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 across 397 models.
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
- 5 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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Find what replaces your water heater
Enter the model number off your old unit and see what is on file today, with the yearly cost difference.
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Find a water heater that fits
Three questions — fuel, hot water need, install space — narrow every model on file to the ones that fit.
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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 figure of 206 therms is computed by this site, not published by the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 0.82 with the federal test's daily hot-water draw for the high draw pattern. The source is the DOE CCD, retrieved 2026-09-19. The registry also lists a maximum flow rate in gallons per minute of 5. That flow rate is a separate measure and is not part of the energy calculation. The energy figure holds only at the test's daily draw. A household that draws more or less hot water than the test will use a different amount of gas, and this page cannot estimate that amount.
Within its class, this model ranks 229th lowest energy use of 397. That places it in the second-highest quarter of the class for energy use, 24 therms above the class median of 182 therms. The high draw pattern describes a larger household, or one where showers and laundry overlap, so the figure is most relevant to readers whose hot-water use looks like that. Readers who compare on energy use alone will find models in this class that use less gas at the same draw pattern. To see those models, find a same-class replacement by model number. The registry data here do not say whether any other factor, such as space or fuel supply, favors this unit or another.
The running cost is not stated in the text because it depends on your state's average residential gas price. Multiplying 206 therms by that price gives the yearly gas cost at the test's draw, and this page does not name an amount or estimate one. Enter your ZIP in the cost calculator to see the figure computed for your state. The methodology for the annual cost explains each step of that calculation. 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 it is not repeated here.
DOE CCD · 2026-09-19