State TK-510U-E 2**
State TK-510U-E 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 figures
- Flow at a 67°F rise
- 5.0gallons per minute
- 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.
Certified figures by listed model
| Model number | UEF | Flow at a 67°F rise (gal/min) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|
| GTS-510U-E 2** | 0.81 | 5.0 | 84% | 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 gas tankless type has a median flow of 4.8 gallons per minute. Its flow at a 67°F rise trails 176 of the 487 gas tankless models.
It was not listed as ENERGY STAR certified on Oct 19, 2026. 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. Its UEF is lower than that of 327 of the 399 gas tankless models with its draw pattern. For its type and draw pattern, the UEF runs from 0.81 to 0.98. Of the energy it spends heating water, 84% ends up in it (its recovery efficiency).
Its test figures match those of 13 other basic models. Besides this brand, 6 brands list one or more of them. For the full group, see the A. O. Smith TK-510U-E 2** page.
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**
- American TK-510U-I 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-I 2**
- Takagi TK-510U-E 2**
1 more basic model carry these figures.
- Every State 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
- Advertised figures. We have none on file for this model.