Verdict
Head-to-head · Best Tankless Water Heaters

Rheem RTEX-24 vs Stiebel Eltron Tempra 36 Plus

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

The short answer

Stiebel Eltron Tempra 36 Plus comes out ahead by a narrow margin (4.7 vs 4.8). The gap is mostly about whole-home electric tankless installs in mild climates — read the strengths below before deciding.

Rheem RTEX-24
Ranked #2 in Best Tankless Water Heaters
Rheem RTEX-24
$485

The RTEX-24 is the cold-climate pick — Rheem's flagship that handles northern winter inlet temps better than competitors.

Strengths
  • 3,900+ reviews proving reliability
  • Excels in cold-inlet conditions (northern climates)
  • Self-modulating heating elements
Watch-outs
  • Slightly louder than Tempra under load
  • No advanced flow control
  • Smaller display
Stiebel Eltron Tempra 36 Plus
Higher ratedRanked #1 in Best Tankless Water Heaters
Stiebel Eltron Tempra 36 Plus
$812

The Tempra 36 Plus is the best-overall pick — Stiebel Eltron's flow control handles whole-home demand without cold-water sandwiching.

Strengths
  • Advanced Flow Control prevents cold-water sandwiching
  • 36 kW max — handles whole-home demand in mild climates
  • 10-year combined warranty
Watch-outs
  • Requires 200A electrical service for full output
  • No Wi-Fi
  • Plumbing install required

How they stack up

Rheem RTEX-24

Best for cold climates. Most user reviews. Cheaper than Tempra.

Stiebel Eltron Tempra 36 Plus

Best whole-home pick. German engineering. Highest amperage required.

Specs side-by-side

SpecRheem RTEX-24Stiebel Eltron Tempra 36 Plus
TypeElectric whole-homeElectric whole-home
Power24 kW36 kW
Self-ModulatingYes
Reviews3,900+
Flow ControlAdvanced
Warranty10-year combined
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