Aquapower Mini 4-2 vs Stiebel Eltron Mini-E 3.5-1: which uses less energy?
At the very small draw pattern the Stiebel Eltron Mini-E 3.5-1 uses 615 kWh a year and the Aquapower Mini 4-2 622 — 6 kWh (1%) less, about 65 kWh over ten years. Both are filed as an electric 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 an electric tankless unit at the very small draw pattern.
| Figure | Aquapower Mini 4-2 | Stiebel Eltron Mini-E 3.5-1 |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.95 | 0.96 (better) |
| Energy use per year (kWh) | 622 | 615 (better) |
| Max flow (GPM) | 0.4 | 0.4 |
| Installed cost range | $1,303–$1,814 | $1,306–$1,838 |
| 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 Stiebel Eltron Mini-E 3.5-1 if running cost matters most: it uses 6 kWh less a year on the same test.
- Pick the Aquapower Mini 4-2 if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Stiebel Eltron Mini-E 3.5-1.
- Neither if you need more than 0.4 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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Aquapower Mini 4-2
Its filed figures, class position and running cost on your ZIP.
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Stiebel Eltron Mini-E 3.5-1
Its filed figures, class position and running cost on your ZIP.