DoesTheMath

Rheem PROE36 S2 RH95 vs Stiebel Eltron PSH 20: which uses less energy?

At the low draw pattern the Stiebel Eltron PSH 20 uses 2,413 kWh a year and the Rheem PROE36 S2 RH95 2,439 — 26 kWh (1%) less, about 262 kWh over ten years. Both are filed as an electric tank, 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 tank at the low draw pattern.

Filed and computed figures
Rheem PROE36 S2 RH95 Stiebel Eltron PSH 20
UEF (Uniform Energy Factor) 0.92 0.93 (better)
Energy use per year (kWh) 2,439 2,413 (better)
First hour rating (gal) 34 30
Rated storage volume (gal) 33 21
Installed cost range $1,548–$1,727 not published
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

Rheem PROE36 S2 RH95: 2,439 kWh a year Stiebel Eltron PSH 20: 2,413 kWh a year

Rheem PROE36 S2 RH95 — 2,439 kWh a year Stiebel Eltron PSH 20 — 2,413 kWh a year

Stiebel Eltron PSH 20 is 26 kWh a year lower than Rheem PROE36 S2 RH95.

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 Stiebel Eltron PSH 20 if running cost matters most: it uses 26 kWh less a year on the same test.
  • Pick the Rheem PROE36 S2 RH95 if you need more hot water in your busiest hour: it lists a first hour rating of 34 gallons against 30.
  • Neither if your household's busiest hour needs more than 34 gallons of hot water — neither lists more.

Each model on its own

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