Rheem SPEX35
Rheem SPEX35 is in the DOE listing as of Oct 26, 2026.
It has a certified UEF of 0.95 and a certified flow of 0.4 gal/min at a 67°F rise.
Its certified flow is 0.4 gal/min at a 67°F rise, while Rheem advertises 2.0 gal/min, no rise stated (Read Oct 5, 2026), so a comparison at the same rise is not possible.
- Electric tankless water heater
- 1 listed model
ENERGY STAR certification does not cover this type of water heater.
Certified and advertised figures
- Flow at a 67°F rise
- 0.4gallons per minuteCertified
- Advertised flow
- 2.0gallons per minuteRheem, no rise stated
- UEF
- 0.95Uniform 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 0.4 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 | 1.00 | 0.95 | The Home Depot | Archived copy, Sep 17, 2025 |
| Flow | 2.0 gal/min, no rise stated | 0.4 gal/min at a 67°F rise | Rheem | Read Oct 5, 2026 |
Certified figures by listed model
| Model number | UEF | Flow at a 67°F rise (gal/min) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|
| RTEH35 | 0.95 | 0.4 | 94% | Very small |
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 0.4 gallons per minute. The median flow among electric tankless models is 0.7 gallons per minute. Among 337 electric tankless models, 233 give more flow at a 67°F rise.
In tests, 95% of the energy went to hot water, so its UEF is 0.95. Its test simulated a day of very small hot water use (its draw pattern). Its UEF is lower than that of 151 of the 272 electric tankless models with its draw pattern. A UEF of 0.96 is the median for its type and draw pattern. Of the energy it spends heating water, 94% ends up in it (its recovery efficiency).
All of its test figures are shared by 2 other basic models. Of those, one or more are under the EEMAX and KWICKSHOT brands.
Also listed as
They carry every figure in the table above.
- Every Rheem basic model
- Every electric tankless water heater certified below 1.0 gallon per minute
- Every electric tankless water heater
Not covered
- Changes to an advertised figure after the date beside it.