Takagi T-H3-OS-N 1**
Takagi T-H3-OS-N 1** is in the DOE listing as of Oct 19, 2026. Takagi T-H3-OS-N 1** is in the ENERGY STAR list as of Oct 19, 2026.
- Gas tankless water heater
- 8 listed models
Its figures are also listed under A. O. Smith T-H3-OS-N 1**.
Certified and advertised figures
- Flow at a 67°F rise
- 5.8gallons per minuteCertified
- Advertised flow
- 10.0gallons per minuteTakagi, 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 5.6 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 | 0.95 | 0.95 | Takagi | Read Oct 4, 2026 |
| Flow | 10.0 gal/min, no rise stated | 5.8 gal/min at a 67°F rise | Takagi | Read Oct 4, 2026 |
| Flow | 10.0 gal/min, no rise stated | 5.8 gal/min at a 67°F rise | SupplyHouse | Archived copy, Apr 18, 2025 |
| Flow | 9.5 gal/min at a 40°F rise | 5.8 gal/min at a 67°F rise | SupplyHouse | Archived copy, Apr 18, 2025 |
| Flow | 7.5 gal/min at a 50°F rise | 5.8 gal/min at a 67°F rise | SupplyHouse | Archived copy, Apr 18, 2025 |
| Flow | 6.3 gal/min at a 60°F rise | 5.8 gal/min at a 67°F rise | SupplyHouse | Archived copy, Apr 18, 2025 |
| Flow | 5.4 gal/min at a 70°F rise | 5.8 gal/min at a 67°F rise | SupplyHouse | Archived copy, Apr 18, 2025 |
Certified figures by listed model
| Model number | UEF | Flow at a 67°F rise (gal/min) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|
| T-H3-OS-N 1** | 0.95 | 5.8 | 96% | High |
| T-H3-OS-P 1*1 | 0.95 | 5.8 | 96% | High |
| TCT-199O-N 1** | 0.95 | 5.8 | 96% | High |
| TCT-199O-P 1*1 | 0.95 | 5.8 | 96% | High |
| TK-540P-NEH 1** | 0.95 | 5.8 | 96% | High |
| TK-540P-PEH 1*1 | 0.95 | 5.8 | 96% | High |
| TK-540X3-NEH 1** | 0.95 | 5.8 | 96% | High |
| TK-540X3-PEH 1*1 | 0.95 | 5.8 | 96% | High |
UEF is the uniform energy factor. A dash means the model has no such figure.
ENERGY STAR certified models
| Model number | UEF | Flow at a 67°F rise (gal/min) | Recovery efficiency |
|---|---|---|---|
| T-H3-OS-N 1** | 0.95 | 5.8 | — |
| T-H3-OS-P 1*1 | 0.95 | 5.8 | — |
| TCT-199O-N 1** | 0.95 | 5.8 | — |
| TCT-199O-P 1*1 | 0.95 | 5.8 | — |
| TK-540P-NEH 1** | 0.95 | 5.8 | — |
| TK-540P-PEH 1*1 | 0.95 | 5.8 | — |
| TK-540X3-NEH 1** | 0.95 | 5.8 | 96% |
| TK-540X3-PEH 1*1 | 0.95 | 5.8 | 96% |
At a 67°F rise, its flow in the test is 5.8 gallons per minute. The median gas tankless model heats 4.8 gallons per minute by 67°F. Of 487 gas tankless models, 26 have a higher flow than this one.
Under this basic model, 8 model numbers are ENERGY STAR certified. In tests, 95% of the energy it uses ends up as hot water (UEF 0.95). The daily hot water use in the test, called its draw pattern, was high. 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 UEF runs from 0.81 to 0.98. Of the energy it spends heating water, 96% ends up in it (its recovery efficiency).
All 8 of its model numbers carry the same certified figures. There are 5 more basic models with the same test figures. Each of the 5 other brands lists one of them. You can find the whole group on the page for the A. O. Smith T-H3-OS-N 1**.
It may qualify for 6 rebate programs. Another 2 rebate programs may accept it if it meets their other terms.
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 Takagi 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
- Changes to an advertised figure after the date beside it.