Mizudo HW199
Mizudo HW199 is in the DOE listing as of Oct 19, 2026.
- Gas tankless water heater
- 2 listed models
Not listed as ENERGY STAR certified on Oct 19, 2026.
Its figures are also listed under Electrolex EHW199.
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
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 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 |
|---|---|---|---|---|
| HW199A1G-LP | 0.81 | 5.0 | 81% | High |
| HW199A1G-NG | 0.81 | 5.0 | 81% | High |
UEF is the uniform energy factor. A dash means the model has no such figure.
It warms 5.0 gallons per minute of water from 58°F to 125°F in the test. The median flow among gas tankless models is 4.8 gallons per minute. Among 487 gas tankless models, 176 give more flow at a 67°F rise.
On Oct 19, 2026, this heater was not listed as ENERGY STAR certified. In tests, 81% of the energy went to hot water, so its UEF is 0.81. In the test, daily hot water use was set to high (its draw pattern). Its UEF is lower than that of 327 of the 399 gas tankless models with its draw pattern. A UEF of 0.93 is the median for its type and draw pattern. When it runs, 81% of the energy it uses reaches the water (its recovery efficiency).
It is the basic model for HW199A1G-LP and HW199A1G-NG. There are 2 more basic models with the same test figures. Of those, one or more are under the Electrolex and Westinghouse brands. You can find the whole group on the page for the Electrolex EHW199.
Also listed as
They carry every figure in the table above.
- Every Mizudo 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.