A. O. Smith ATO-140X3-N 1**
A. O. Smith ATO-140X3-N 1** is in the DOE listing as of Oct 19, 2026.
- Gas tankless water heater
- 1 listed model
Not listed as ENERGY STAR certified on Oct 19, 2026.
Its figures are also listed under A. O. Smith ATI-140B-N 1**.
Certified and advertised figures
- Flow at a 67°F rise
- 3.6gallons per minuteCertified
- Advertised flow
- 7.7gallons per minuteA. O. Smith, up to, no rise stated
- UEF
- 0.81Uniform energy factor
Your fixtures at once
Change your hour and flowFlow where you live
The heater gives less flow when colder incoming water needs a bigger rise.
- Cold water
- Cold water must be at least 10°F colder than the hot water setting.
- Flow estimate
- The estimate uses the lowest certified flow among the listed models. It is about 3.4 gal/min at a 70°F rise.
Flow limits
- The estimate excludes the flow needed to turn the heater on, heat lost in pipes, and installation.
- Cold water from a well or long pipe run can differ from the temperature you enter.
- Without a stated flow limit, estimates for warmer water may exceed the heater’s actual flow.
Advertised and certified figures
| Figure | Advertised | Certified | Advertiser | Read |
|---|---|---|---|---|
| UEF | 0.82 | 0.81 | A. O. Smith | Read Oct 4, 2026 |
| UEF | 0.81 | 0.81 | A. O. Smith | Read Oct 4, 2026 |
| Flow | 7.7 gal/min, no rise stated | 3.6 gal/min at a 67°F rise | A. O. Smith | Read Oct 4, 2026 |
| Flow | up to 7.7 gal/min, no rise stated | 3.6 gal/min at a 67°F rise | A. O. Smith | Read Oct 4, 2026 |
| Flow | 3.6 gal/min at a 67°F rise | 3.6 gal/min at a 67°F rise | A. O. Smith | Read Oct 4, 2026 |
Certified figures by listed model
| Model number | UEF | Flow at a 67°F rise (gal/min) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|
| ATO-140X3-N 1** | 0.81 | 3.6 | 84% | Medium |
UEF is the uniform energy factor. A dash means the model has no such figure.
It warms 3.6 gallons per minute of water from 58°F to 125°F in the test. The median flow among gas tankless models is 4.8 gallons per minute. Among 487 gas tankless models, 409 give more flow at a 67°F rise.
As of Oct 19, 2026, it was not listed as ENERGY STAR certified. In the test, 19% of its energy does not reach the hot water (UEF 0.81). Its test ran at the medium level of daily hot water use. Its UEF is lower than that of 48 of the 77 gas tankless models with its draw pattern. A UEF of 0.82 is the median for its type and draw pattern. Of the energy it spends heating water, 84% ends up in it (its recovery efficiency).
There are 10 more basic models with the same test figures. Between them, those basic models carry 4 other brand names. You can find the whole group on the page for the A. O. Smith ATI-140B-N 1**.
Also listed as
They carry every figure in the table above.
- Every A. O. Smith basic model
- Every gas tankless water heater certified below 4.0 gallons per minute
- Every gas tankless water heater
- The most-searched gas tankless models side by side
Not covered
- Changes to an advertised figure after the date beside it.