Stiebel Eltron Tempra 20 Plus Tankless Water Heater, 19.2kW
Stiebel Eltron's German-engineered electric tankless is the most reliable whole-house electric option -- with Advanced Flow Control that prevents cold water bursts when demand spikes.
Updated
- Strong feedback from Amazon buyers
- Advanced Flow Control prevents cold water bursts under high simultaneous demand
- 19.2kW at 240V -- requires an 80A dedicated circuit
- German engineering with a track record measured in decades
Best For / Not For
Best for
- Homes without natural gas that want a whole-house on-demand electric solution
- Buyers in warmer climates where groundwater enters above 55°F -- electric efficiency shines at lower temperature rises
- Households with a 200A electrical panel and capacity for an 80A dedicated circuit
Not for
- Very cold climates -- 19.2kW at cold groundwater temperatures may only achieve 2-3 GPM output
- Homes with a 100A or smaller electrical panel where adding 80A of service is not feasible
- Buyers who expect gas-equivalent whole-house flow in northern states without upgrading to a larger electric unit
Key Details
What Advanced Flow Control Actually Does
Most electric tankless heaters fail the same way: when two showers run simultaneously, the unit's heating elements cannot keep up with the increased flow, and the output temperature drops. You get lukewarm water instead of hot. Budget brands handle this badly -- the temperature yo-yos, and showers become uncomfortable. The Tempra's Advanced Flow Control takes a different approach: when demand exceeds capacity, it automatically reduces flow rate to maintain the target output temperature. You get slightly less pressure, but the temperature stays consistent.
This is the right tradeoff. A short drop in pressure during peak demand is barely noticeable in practice. An unexpected cold burst mid-shower is jarring. The Tempra's technology choice reflects a real understanding of how household hot water is used.
Electrical Requirements and Real-World Planning
The 19.2kW Tempra 20 Plus requires two 40A breakers or one 80A breaker on a 240V dedicated circuit. If your home has a 200A electrical panel with available capacity, this is a straightforward addition for a licensed electrician. If your panel is already near capacity or if you have a 100A main service, the upgrade cost -- potentially including a panel upgrade -- can equal or exceed the heater cost itself. Get an electrician to assess your panel before purchasing.
In warm climates where groundwater enters at 60-70°F, a 19.2kW unit can deliver 3-4 GPM comfortably -- enough for one shower and a sink, or two low-flow showers. For whole-house coverage in a warm climate, this sizing works. In cold climates, step up to the Tempra 24 Plus or the Tempra 29 Plus, which require proportionally larger electrical service.
Pros and Cons
Pros
- Strong feedback from verified Amazon buyers
- Advanced Flow Control is the best flow management technology in electric tankless
- German build -- Stiebel Eltron makes the Tempra series in Germany
- Self-modulating power draw -- uses only what is needed for demand
- Compact unit fits in small mechanical rooms or closets
Cons
- Requires an 80A dedicated 240V circuit -- significant electrical work for many homes
- Flow rate in cold climates is limited by physics -- electric heat output is fixed at 19.2kW
- Higher upfront cost compared to storage tank electric heaters
Bottom Line
Stiebel Eltron Tempra 20 Plus is a Buy. It is the most reliable whole-house electric tankless water heater available, with German engineering and Advanced Flow Control that separates it from every budget competitor. Verify your electrical panel has the capacity for an 80A dedicated circuit before purchasing, and size for your climate's groundwater temperature.
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