DoesTheMath

ARISTON AURES SM 6.5 240V US* vs Mizudo ET008: which uses less energy?

At the very small draw pattern the ARISTON AURES SM 6.5 240V US* uses 615 kWh a year and the Mizudo ET008 628 — 13 kWh (2%) less, about 131 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.

Filed and computed figures
ARISTON AURES SM 6.5 240V US* Mizudo ET008
UEF (Uniform Energy Factor) 0.96 (better) 0.94
Energy use per year (kWh) 615 (better) 628
Max flow (GPM) 0.7 0.7
Installed cost range $1,306–$1,838 $1,300–$1,790
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

ARISTON AURES SM 6.5 240V US*: 615 kWh a year Mizudo ET008: 628 kWh a year

ARISTON AURES SM 6.5 240V US* — 615 kWh a year Mizudo ET008 — 628 kWh a year

ARISTON AURES SM 6.5 240V US* is 13 kWh a year lower than Mizudo ET008.

DOE CCD · 2026-09-19

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Enter your ZIP to price both units on the same rate where you live.

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 ARISTON AURES SM 6.5 240V US* if running cost matters most: it uses 13 kWh less a year on the same test.
  • Pick the Mizudo ET008 if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the ARISTON AURES SM 6.5 240V US*.
  • Neither if you need more than 0.7 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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