A. O. Smith R4LA-280E 1**
A. O. Smith R4LA-280E 1** is in the DOE listing as of Oct 26, 2026.
It has a certified UEF of 0.92 and a certified flow of 2.5 gal/min at a 67°F rise.
Its advertised flow of 2.5 gal/min at a 67°F rise from A. O. Smith matches the certified 2.5 gal/min at a 67°F rise (Read Oct 4, 2026).
- Electric tankless water heater
- 5 listed models
ENERGY STAR certification does not cover this type of water heater.
Certified and advertised figures
- Flow at a 67°F rise
- 2.5gallons per minuteCertified
- Advertised flow
- 2.5gallons per minuteA. O. Smith, at a 67°F rise
- UEF
- 0.92Uniform 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 2.4 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 | 0.92 | 0.92 | A. O. Smith | Read Oct 4, 2026 |
| Flow | 2.5 gal/min at a 67°F rise | 2.5 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 |
|---|---|---|---|---|
| C4LA-280E 1** | 0.92 | 2.5 | 98% | — |
| C4LA-280X 1** | 0.92 | 2.5 | 98% | — |
| R4LA-280E 1** | 0.92 | 2.5 | 98% | — |
| R4LA-280X 1** | 0.92 | 2.5 | 98% | — |
| R4LR-280E 1** | 0.92 | 2.5 | 98% | — |
UEF is the uniform energy factor. A dash means the model has no such figure.
It heats 2.5 gallons per minute of water by 67°F in the test. The median electric tankless model heats 0.7 gallons per minute by 67°F. Its flow at a 67°F rise trails 13 of the 337 electric tankless models.
In the test, 8% of its energy does not reach the hot water (UEF 0.92). When it runs, 98% of the energy it uses reaches the water (its recovery efficiency).
A tag or quote may show any of its 5 model numbers. Its test figures match those of 2 other basic models. Those basic models are sold with RELIANCE WATER HEATERS and State as their brand names.
Also listed as
They carry every figure in the table above.
- Every A. O. Smith basic model
- Every electric tankless water heater certified at 2.0 gallons per minute or more
- Every electric tankless water heater
Not covered
- Changes to an advertised figure after the date beside it.