LAARS LT150NXX1 vs NAVIEN NPE-180A2: which uses less energy?
At the high draw pattern the LAARS LT150NXX1 uses 173 therms a year and the NAVIEN NPE-180A2 178 — 5 therms (3%) less, about 55 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 high draw pattern.
| Figure | LAARS LT150NXX1 | NAVIEN NPE-180A2 |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.98 (better) | 0.95 |
| Energy use per year (therms) | 173 (better) | 178 |
| Max flow (GPM) | 4.3 | 4.3 |
| Installed cost range | $2,499–$3,570 | $2,358–$3,405 |
| ENERGY STAR certified | yes | yes |
| Sound level (dB) | 44 | not filed |
| On the market since | 2026-02-01 | 2021-01-01 |
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.
- Both are ENERGY STAR certified, which requires a manufacturer warranty of at least six years; the actual term for each model is not published.
- Time on the market, as filed with ENERGY STAR: the LAARS LT150NXX1 since 2026-02-01, the NAVIEN NPE-180A2 since 2021-01-01. A sale date, not a lifespan.
Which should you pick?
- Pick the LAARS LT150NXX1 if running cost matters most: it uses 5 therms less a year on the same test.
- Pick the NAVIEN NPE-180A2 if the installed price matters more than the running cost: its modeled installed range is $2,358–$3,405 against $2,499–$3,570.
- Neither if you need more than 4.3 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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LAARS LT150NXX1
Its filed figures, class position and running cost on your ZIP.
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NAVIEN NPE-180A2
Its filed figures, class position and running cost on your ZIP.