Mizudo FDG-CS90
Mizudo FDG-CS90 is in the DOE listing as of Oct 26, 2026.
It has a certified UEF of 0.82–0.84 and a certified flow of 2.2–2.3 gal/min at a 67°F rise.
- Gas tankless water heater
- 2 listed models
Not listed as ENERGY STAR certified on Oct 26, 2026.
Certified figures
- Flow at a 67°F rise
- 2.2–2.3gallons per minute
- UEF
- 0.82–0.84Uniform energy factor
The 2 listed models differ. A range runs from the lowest figure to the highest.
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 2.1 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 |
|---|---|---|---|---|
| FDG-CS90AG-LP | 0.84 | 2.3 | 85% | Low |
| FDG-CS90AG-NG | 0.82 | 2.2 | 82% | Low |
UEF is the uniform energy factor. A dash means the model has no such figure.
Its flow at a 67°F rise is 2.2 to 2.3 gallons per minute, by model number. The median flow among gas tankless models is 4.8 gallons per minute. Among 487 gas tankless models, 479 give more flow at a 67°F rise.
As of Oct 26, 2026, it was not listed as ENERGY STAR certified. Its listed models turn 82 to 84% of the energy used into hot water (UEF 0.82 to 0.84). Its test ran at the low level of daily hot water use. Among 9 gas tankless models with its draw pattern, none reaches a higher UEF than this one. A UEF of 0.82 is the median for its type and draw pattern.
It is the basic model for FDG-CS90AG-LP and FDG-CS90AG-NG.
It may qualify for one rebate program if it meets terms its figures do not show.
Rebates
| Program | State | Status | Program page |
|---|---|---|---|
| SoCalGas High-Efficiency or ENERGY STAR Certified Natural Gas Tankless Water Heaters rebate | CA | 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 Mizudo basic model
- Every gas tankless water heater certified below 4.0 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.