LOCHINVAR T-H3M-OS-N 1** vs NAVIEN NPE-150S2: which uses less energy?
At the medium draw pattern the NAVIEN NPE-150S2 uses 119 therms a year and the LOCHINVAR T-H3M-OS-N 1** 122 — 3 therms (2%) less, about 26 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 | LOCHINVAR T-H3M-OS-N 1** | NAVIEN NPE-150S2 |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.91 | 0.93 (better) |
| Energy use per year (therms) | 122 | 119 (better) |
| Max flow (GPM) | 3.5 | 3.4 |
| Installed cost range | $2,169–$3,184 | $2,264–$3,294 |
| ENERGY STAR certified | not matched | not matched |
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 NAVIEN NPE-150S2 if running cost matters most: it uses 3 therms less a year on the same test.
- Pick the LOCHINVAR T-H3M-OS-N 1** if you run more fixtures at once: it lists 3.5 GPM against 3.4.
- Neither if you need more than 3.5 GPM at the same time — neither unit lists more. Check how to size a tankless unit by GPM.
Each model on its own
-
LOCHINVAR T-H3M-OS-N 1**
Its filed figures, class position and running cost on your ZIP.
-
NAVIEN NPE-150S2
Its filed figures, class position and running cost on your ZIP.