American ATO-199B-N 1**
American ATO-199B-N 1** is in the DOE listing as of Oct 19, 2026.
- Gas tankless water heater
- 2 listed models
Not listed as ENERGY STAR certified on Oct 19, 2026.
Its figures are also listed under A. O. Smith ATO-199B-N 1**.
Certified and advertised figures
- Flow at a 67°F rise
- 5.0gallons per minuteCertified
- Advertised flow
- 10.5gallons per minuteAmerican, no rise stated
- UEF
- 0.82Uniform energy factor
Your fixtures at once
Change your hour and flowFlow where you live
Colder incoming water needs a bigger rise, so the heater gives less flow.
- 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 4.8 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 | 0.82 | American | Read Oct 4, 2026 |
| Flow | 10.5 gal/min, no rise stated | 5.0 gal/min at a 67°F rise | American | Read Oct 4, 2026 |
| Flow | 5.0 gal/min at a 67°F rise | 5.0 gal/min at a 67°F rise | American | Read Oct 4, 2026 |
Certified figures by listed model
| Model number | UEF | Flow at a 67°F rise (gal/min) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|
| MTO-199B-N 1** | 0.82 | 5.0 | 86% | High |
| MTO-199X3-N 1** | 0.82 | 5.0 | 86% | High |
UEF is the uniform energy factor. A dash means the model has no such figure.
At a 67°F rise, its flow in the test is 5.0 gallons per minute. The median flow among gas tankless models is 4.8 gallons per minute. Among 487 gas tankless models, 176 give more flow at a 67°F rise.
On Oct 19, 2026, this heater was not listed as ENERGY STAR certified. In tests, 82% of the energy went to hot water, so its UEF is 0.82. The daily hot water use in the test, called its draw pattern, was high. Among 399 gas tankless models on its draw pattern, 243 have a higher UEF. On its draw pattern, the median gas tankless UEF is 0.93. Of the energy it spends heating water, 86% ends up in it (its recovery efficiency).
Its 2 model numbers are MTO-199B-N 1** and MTO-199X3-N 1**. There are 4 more basic models with the same test figures. Each of the 4 other brands lists one of them. For the full group, see the A. O. Smith ATO-199B-N 1** page.
It may qualify for one rebate program if it meets their other terms.
Also listed as
They carry every figure in the table above.
Rebates
| Program | State | Status | Program page |
|---|---|---|---|
| SoCalGas High-Efficiency or ENERGY STAR Certified Natural Gas Tankless Water Heaters rebate | CA | May qualify if it meets the other terms | Its own page |
Programs change their terms. Check the program's own page before you buy.
- Every American basic model
- Every gas tankless water heater certified at 5.0 to 5.9 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.