NAVIEN NPE-150S2 vs RINNAI (RX130I) REU-NB2024FF-US: which uses less energy?
At the medium draw pattern the RINNAI (RX130I) REU-NB2024FF-US uses 114 therms a year and the NAVIEN NPE-150S2 119 — 5 therms (4%) less, about 49 therms over ten years. Both are filed as a gas tankless unit, so the comparison holds. Enter your ZIP below to price the difference.
Side by side
Compared within one class only: models filed as a gas tankless unit at the medium draw pattern.
| Figure | NAVIEN NPE-150S2 | RINNAI (RX130I) REU-NB2024FF-US |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.93 | 0.97 (better) |
| Energy use per year (therms) | 119 | 114 (better) |
| Max flow (GPM) | 3.4 | 3.8 |
| Installed cost range | $2,264–$3,294 | $2,452–$3,515 |
| ENERGY STAR certified | not matched | yes |
| On the market since | not filed | 2024-03-01 |
What it costs to run
Reliability
Not published: Reliability, failure rates and each model’s actual warranty term.
The registries these figures come from certify energy performance under a federal test; none of them records how long a unit lasts or how often it fails, so this page does not rank the two on reliability.
What is here instead:
- The filed efficiency, capacity and tank size of both models, side by side below.
- The actual warranty term is printed in each model’s documentation, not in any registry.
Which should you pick?
- Pick the RINNAI (RX130I) REU-NB2024FF-US if running cost matters most: it uses 5 therms less a year on the same test.
- Pick the NAVIEN NPE-150S2 if the installed price matters more than the running cost: its modeled installed range is $2,264–$3,294 against $2,452–$3,515.
- Neither if you need more than 3.8 GPM at the same time — neither unit lists more. Check how to size a tankless unit by GPM.
Each model on its own
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NAVIEN NPE-150S2
Its filed figures, class position and running cost on your ZIP.
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RINNAI (RX130I) REU-NB2024FF-US
Its filed figures, class position and running cost on your ZIP.