The answer — one pick, priced
Get the
Stiebel Eltron Tempra 36 Plus
no budget ceiling
The consensus best overall across 7 expert sources — 36 kW and up to 7.5 GPM, with Advanced Flow Control that holds your set temperature instead of dumping cold water.
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Fit ledger — need → measured evidence
■ The catch — co-equal billing, always
It needs 150 amps. A 36 kW unit runs on three 50A 240V breakers and typically a 200A panel — and the service upgrade that implies costs $1,000–$3,000+ on its own, a bill the $810 sticker completely hides. Get an electrician's load calculation before you buy.
Dealbreaker? Runner-up №1 drops to 112.5A and costs $310 less ↓
■ Every product has a catch. Verdicts that hide it are how bad buys happen.
Runners-up — if your needs differ
Adjacent verdicts — same method
Traps — this verdict avoids
Phantom GPM
Headline flow rates are quoted at a modest temperature rise. A unit rated 7.5 GPM at a 35°F rise can deliver under 4 GPM at a 70°F rise — a heater that runs four showers in Florida may not run one in Minnesota. Size by your winter inlet temperature, never by the box.
The panel bill the price hides
A 36 kW whole-house unit draws 150A — three 50A 240V breakers — and 27–36 kW units routinely force a 200A panel or service upgrade costing $1,000–$3,000+ on top of the heater.
The tax credit is gone
The federal 25C credit (30% of cost, up to $600) applied only to property placed in service on or before 2025-12-31. A 2026 install earns no federal credit — budget the full sticker and check state/utility rebates instead.
Provenance — 7 sources, dated
Winners are picked before affiliate payouts are checked, from the full research dossier at knowledgelib.io. Prices, stock and listings are re-verified monthly by an automated pipeline. Some links earn us a commission — it never changes the pick, and we say so here rather than in a footer you'd never read.