DoesTheMath

A. O. SMITH UPVA-45E 1** vs ThermoMate ET045: which uses less energy?

At the very small draw pattern the ThermoMate ET045 uses 562 kWh a year and the A. O. SMITH UPVA-45E 1** 642 — 79 kWh (12%) less, about 795 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
A. O. SMITH UPVA-45E 1** ThermoMate ET045
UEF (Uniform Energy Factor) 0.92 1.05 (better)
Energy use per year (kWh) 642 562 (better)
Max flow (GPM) 0.5 0.5
Installed cost range $1,294–$1,742 not published
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

A. O. SMITH UPVA-45E 1**: 642 kWh a year ThermoMate ET045: 562 kWh a year

A. O. SMITH UPVA-45E 1** — 642 kWh a year ThermoMate ET045 — 562 kWh a year

ThermoMate ET045 is 80 kWh a year lower than A. O. SMITH UPVA-45E 1**.

DOE CCD · 2026-09-19

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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 ThermoMate ET045 if running cost matters most: it uses 79 kWh less a year on the same test.
  • Pick the A. O. SMITH UPVA-45E 1** if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the ThermoMate ET045.
  • Neither if you need more than 0.5 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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