Every model below is published with verified specs. Savings calculated from EIA average energy prices.
Quick verdict
Lowest annual bill
Navien NPE-210S2
$239/yr
Most efficient
Navien NPE-210S2
UEF 0.96
Shortest unit
Takagi T-H3J-OS-N-1
22.5" tall
What a typical gas tank unit costs to operate
Annual$358/yr
10-year projection$3,580
Based on Rheem XG40T09HE40U0 (UEF 0.65). U.S. average energy rates (EIA).
Replacement options
Navien NPE-210S2
Condensing TanklessUEF 0.96 / ~$239/yr
Annual savings$119/yr
10-year savings$1,190
Install changes
- No gas venting needed with electric replacement
Navien NPE-240S2
Condensing TanklessUEF 0.96 / ~$239/yr
Annual savings$119/yr
10-year savings$1,190
Install changes
- No gas venting needed with electric replacement
Takagi T-H3J-OS-N-1
Condensing TanklessUEF 0.95 / ~$242/yr
Annual savings$116/yr
10-year savings$1,160
Install changes
- No gas venting needed with electric replacement
Rheem RTGH-95DVLN-3
Condensing TanklessUEF 0.93 / ~$250/yr
Annual savings$108/yr
10-year savings$1,080
Side-by-side comparison
| Spec | NPE-210S2 | NPE-240S2 | T-H3J-OS-N-1 | RTGH-95DVLN-3 |
|---|---|---|---|---|
| UEF | 0.96 | 0.96 | 0.95 | 0.93 |
| Annual Cost | $239/yr | $239/yr | $242/yr | $250/yr |
| Annual Savings | $119/yr | $119/yr | $116/yr | $108/yr |
| Height | 27.4" | 27.4" | 22.5" | 23" |
● Best value in each row.
Install considerations: gas tank to gas tankless
Items your installer may need. Actual requirements depend on your existing setup, local code, and jurisdiction.
The federal tax credit of up to $2,000 under IRA Section 25C expired December 31, 2025. State and utility rebates may still apply.
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Sources. ENERGY STAR, manufacturer spec sheets, EIA average energy prices.Methodology