American TK-510U-I 2**
American TK-510U-I 2** 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 TK-510U-E 2**.
Certified and advertised figures
- Flow at a 67°F rise
- 5.0gallons per minuteCertified
- Advertised flow
- 10.0gallons per minuteAmerican, up to, no rise stated
- UEF
- 0.81Uniform energy factor
Your fixtures at once
Change your hour and flowFlow where you live
A bigger rise from colder incoming water leaves the heater with 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 | 0.81 | 0.81 | American | Read Oct 5, 2026 |
| Flow | up to 10.0 gal/min, no rise stated | 5.0 gal/min at a 67°F rise | American | Read Oct 5, 2026 |
| Flow | 5.0 gal/min at a 67°F rise | 5.0 gal/min at a 67°F rise | American | Read Oct 5, 2026 |
Certified figures by listed model
| Model number | UEF | Flow at a 67°F rise (gal/min) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|
| GT-510U-I 2** | 0.81 | 5.0 | 84% | High |
UEF is the uniform energy factor. A dash means the model has no such figure.
It warms 5.0 gallons per minute of water from 58°F to 125°F in the test. The median gas tankless model heats 4.8 gallons per minute by 67°F. 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, 81% of the energy it uses ends up as hot water (UEF 0.81). The daily hot water use in the test, called its draw pattern, was high. Of 399 gas tankless models with the same draw pattern, 327 have a higher UEF. On its draw pattern, the median gas tankless UEF is 0.93. When it runs, 84% of the energy it uses reaches the water (its recovery efficiency).
Its test figures match those of 13 other basic models. In all, 6 other brands list one or more of them. For the full group, see the A. O. Smith TK-510U-E 2**.
Also listed as
They carry every figure in the table above.
- A. O. Smith TK-510U-E 2**
- A. O. Smith TK-510U-I 2**
- American TK-510U-E 2**
- Lochinvar TK-510U-E 2**
- Lochinvar TK-510U-I 2**
- Navien NHW700-199AE-NG
- Navien NHW700-199AI-NG
- RELIANCE WATER HEATERS TK-510U-E 2**
- RELIANCE WATER HEATERS TK-510U-I 2**
- State TK-510U-E 2**
- State TK-510U-I 2**
- Takagi TK-510U-E 2**
1 more basic model carry these figures.
- 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.