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State ATM-199M-N 1**

State ATM-199M-N 1** is in the DOE listing as of Oct 19, 2026. State ATM-199M-N 1** is in the ENERGY STAR list as of Oct 19, 2026.

  • Gas tankless water heater
  • 4 listed models

Its figures are also listed under A. O. Smith ATM-199M-N 1**.

Flow at a 67°F rise
6.0gallons per minute
UEF
0.95Uniform energy factor
See it among every gas tankless model

Flow 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 5.7 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.

Product history

State ATM-199M-N 1** was in the DOE listing by Oct 1, 2026.

State ATM-199M-N 1** has a recorded ENERGY STAR market-availability date of May 15, 2025. It first appeared in the ENERGY STAR list between March 2025 and June 2025.

Certified figures by listed model

Model numberUEFFlow at a 67°F rise (gal/min)Recovery efficiencyDraw pattern
STM-199M-N 1**0.956.096%High
STM-199M-P 1*10.956.096%High
STM-199X3-N 1**0.956.096%High
STM-199X3-P 1*10.956.096%High

UEF is the uniform energy factor. A dash means the model has no such figure.

ENERGY STAR certified models

Model numberUEFFlow at a 67°F rise (gal/min)Recovery efficiency
STM-199M-N 1**0.956.096%
STM-199M-P 1*10.956.096%
STM-199X3-N 1**0.956.096%
STM-199X3-P 1*10.956.096%

At a 67°F rise, its flow in the test is 6.0 gallons per minute. The median flow among gas tankless models is 4.8 gallons per minute. Among 487 gas tankless models, 4 give more flow at a 67°F rise.

It has 4 model numbers that are ENERGY STAR certified. In the test, 5% of its energy does not reach the hot water (UEF 0.95). Its test ran at the high level of daily hot water use. Of 399 gas tankless models with the same draw pattern, 49 have a higher UEF and 217 a lower one. For its type and draw pattern, the UEF runs from 0.81 to 0.98. When it runs, 96% of the energy it uses reaches the water (its recovery efficiency).

It is sold under 4 model numbers in all. Its test figures match those of 8 other basic models. Besides this brand, 6 brands list one or more of them. You can find the whole group on the page for the A. O. Smith ATM-199M-N 1**.

In 7 states, 6 rebate programs may accept it. Another 2 programs may accept it if it meets their other terms.

Also listed as

They carry every figure in the table above.

Rebates

ProgramStateStatusProgram page
SoCalGas High-Efficiency or ENERGY STAR Certified Natural Gas Tankless Water Heaters rebate CA May qualify Its own page
Colorado Springs Utilities Water heater rebate (gas storage, gas tankless) CO May qualify Its own page
Nicor Gas Energy Efficiency Rebates for Your Home (gas tankless) IL May qualify if it meets the other terms Its own page
DTE Energy Water Heaters (gas storage, gas tankless) MI May qualify Its own page
Xcel Energy MINNESOTA RESIDENTIAL ENERGY EFFICIENCY PROGRAMS (gas storage, gas tankless) MN May qualify Its own page
PSE&G Tankless Water Heaters NJ May qualify Its own page
Energy Trust of Oregon Residential Incentives OR, WA May qualify Its own page
Focus on Energy (gas tankless) WI May qualify if it meets the other terms Its own page

Programs change their terms. Check the program's own page before you buy.

Updated Oct 19, 2026 · Methodology

Not covered

  • Advertised figures. We have none on file for this model.