Midea MGWH150OSNN vs RINNAI (RUCS65I) REU-KCM2025FFU-US: which uses less energy?
At the medium draw pattern the RINNAI (RUCS65I) REU-KCM2025FFU-US uses 130 therms a year and the Midea MGWH150OSNN 135 — 5 therms (4%) less, about 48 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 | Midea MGWH150OSNN | RINNAI (RUCS65I) REU-KCM2025FFU-US |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.82 | 0.85 (better) |
| Energy use per year (therms) | 135 | 130 (better) |
| Max flow (GPM) | 3.8 | 3.7 |
| Installed cost range | $1,745–$2,687 | $1,886–$2,853 |
| 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 RINNAI (RUCS65I) REU-KCM2025FFU-US if running cost matters most: it uses 5 therms less a year on the same test.
- Pick the Midea MGWH150OSNN if you run more fixtures at once: it lists 3.8 GPM against 3.7.
- 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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Midea MGWH150OSNN
Its filed figures, class position and running cost on your ZIP.
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RINNAI (RUCS65I) REU-KCM2025FFU-US
Its filed figures, class position and running cost on your ZIP.