Radiant SFK 55
Radiant SFK 55 is in the ENERGY STAR list as of Oct 26, 2026.
It has a certified UEF of 0.95 and a certified flow of 5.5 gal/min at a 67°F rise.
- Gas tankless water heater
- 1 listed model
No certified figures were found under this model number. Units made for another brand are often certified under that brand's basic model.
Certified figures
- Flow at a 67°F rise
- 5.5gallons per minute
- 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 5.3 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
Radiant SFK 55 has a recorded ENERGY STAR market-availability date of Apr 23, 2025. It first appeared in the ENERGY STAR list between March 2025 and June 2025.
ENERGY STAR certified models
| Model number | UEF | Flow at a 67°F rise (gal/min) | Recovery efficiency |
|---|---|---|---|
| SFK 55 | 0.95 | 5.5 | 98% |
It heats 5.5 gallons per minute of water by 67°F in the test. The median flow among gas tankless models is 4.8 gallons per minute. Among 487 gas tankless models, 92 give more flow at a 67°F rise.
Its single model number, SFK 55, is ENERGY STAR certified. In the test, 5% of its energy does not reach the hot water (UEF 0.95). Its test simulated a day of high hot water use (its draw pattern). 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 median UEF is 0.93. While it heats water, 98% of the energy used goes into the water (its recovery efficiency).
All of its test figures are shared by one other basic model.
It may qualify for 6 rebate programs. It may qualify for 2 more if it meets terms its figures do not show.
Also listed as
They carry every figure in the table above.
Rebates
| Program | State | Status | Program 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.
- Every Radiant 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.