A. O. SMITH TK-310C-NI 1**
0.81 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).
Checking this unit? The A. O. SMITH TK-310C-NI 1**, a gas tankless unit, uses 209 therms of natural gas a year at the high draw pattern, the standard daily hot-water usage DOE tests against. That is 27 therms above the class median of 182 therms; it ranks 323rd lowest in energy use of 397.
Energy use per year
209 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 323 of 397, lowest energy first.
Solid line: this model (209 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
- 0.81 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
- 4.6 gal/min DOE CCD · 2026-09-19
What it costs to install
$1,698–$2,632 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 0.81 · Grade G Price it on your ZIP
The figure of 209 therms is computed by this site, not the registry. It uses the registry's UEF, the ratio of hot water delivered to energy used, which is 0.81 for this model. That value is combined with the federal test's daily hot-water draw for the high draw pattern. The result applies only at that draw. A household may use more or less hot water, so real gas use can differ. The source is the DOE CCD, retrieved 2026-09-19. Full steps are in the methodology for the annual cost.
The 27 therms gap to the class median applies at the high draw pattern only. That pattern describes a larger household, or one where showers and laundry overlap. Among the 397 models compared, this unit falls in the highest quarter of its class for energy use. The same-class replacement finder lists other models by model number. This model's maximum flow rate in gallons per minute is 4.6. The registry data does not show whether that flow meets a particular home's demand. That question is not assessed here. The UEF of 0.81 is the same value used in the energy calculation above.
The running cost is not stated here because it depends on your state's average residential gas price. You can price 209 therms at your own rate with the cost calculator for your ZIP. The 27 therms difference from the class median is priced at the same rate, so its cost also varies by state. A household that draws less hot water than the federal test's daily draw would use less than 209 therms. The registry gives no figure for that case, so it is not available here. To narrow models by fuel, space and size, use the water heater selector.
DOE CCD · 2026-09-19