The Stiebel Eltron Tempra is the benchmark whole-home electric tankless water heater — no gas line required, no venting required, 99% efficiency, and the only electric tankless on the market with Advanced Flow Control. Manufactured in Germany by a company that has been building tankless electric water heaters since 1924, the Tempra lineup covers every residential application from a single bathroom in a warm climate all the way to a large home in a cold climate — with six kW sizes available in both the Trend and Plus series. This guide covers every model, every spec, how to size the right one, and what makes the Tempra Plus worth the upgrade.
PlumbersCrib.com carries the full Stiebel Eltron Tempra lineup — Trend and Plus series in all six sizes. Browse all Tempra models at PlumbersCrib.com or contact our team for help sizing the right model.
Why electric tankless — the case for no gas, no venting
Gas tankless water heaters deliver higher flow rates per unit — but they require a gas line, a flue or direct vent, combustion air, and a meter and regulator capable of handling 140,000 to 199,900 BTU/h. On retrofit installations, the gas infrastructure work can exceed the cost of the water heater itself. The Tempra eliminates all of it — no gas line, no venting, no combustion air calculation, no meter upgrade. A 240V electrical connection and a water line are the only requirements.
The Tempra is also 99% efficient with zero standby heat loss — no energy is consumed when hot water is not being drawn. Compared to a conventional electric tank water heater, a tankless electric unit typically uses 15–20% less energy, with savings potentially higher depending on usage habits. Conventional electric tank heaters lose 15–20% of their total energy consumption to the surrounding environment — standby heat loss that the Tempra avoids entirely by design.
Where the Tempra makes the most sense. All-electric homes and buildings, retrofits where gas infrastructure upgrades are cost-prohibitive, installations where venting is difficult or impossible, and any application where simplicity of installation and long-term efficiency are the priorities over maximum flow rate capacity.
Tempra Trend vs Tempra Plus — what is the difference
Both Trend and Plus series share the same core platform — copper sheathed heating elements in copper cylinders, microprocessor temperature control, electronic flow switch, digital temperature display, 3/4" NPT water connections, and the 7-year leakage / 3-year parts warranty. The single difference is Advanced Flow Control — exclusive to the Plus series.
Advanced Flow Control (Plus only). Invented by Stiebel Eltron and protected by German patent DE 3805441 C2 — no other manufacturer of tankless electric water heaters has anything like it. When demand exceeds the unit's capacity, Advanced Flow Control automatically and slightly reduces the flow of water to maintain delivery at the set temperature. The result: the client gets slightly less water, but always at the temperature they set — never a cold water burst or a temperature drop during peak demand.
Tempra Trend — no Advanced Flow Control. When demand exceeds capacity, the output temperature drops. For installations where the unit is correctly sized with comfortable headroom above peak demand, the Trend performs identically to the Plus. For installations where peak demand may occasionally push the unit near its capacity limit, the Plus is the safer specification.
Which to spec? In cold-climate installations where the temperature rise requirement limits available GPM, spec the Plus — Advanced Flow Control provides a safety net when demand pushes the unit near its limits. In warm-climate installations where the selected model has significant GPM headroom above peak demand, the Trend is a cost-effective choice that performs identically under normal conditions.
Full model lineup and specs
All specs confirmed from Stiebel Eltron spec sheet Rev. 6.2025. All models: 240V single phase, 3/4" NPT water connections, min. 30 PSI / max. 150 PSI, max. output 140°F, max. inlet 131°F, dimensions 16-5/8" W x 14-1/2" H x 4-5/8" D.
| Model | Series | kW | Amps | Breakers | Wire | UEF | Weight | Order |
|---|---|---|---|---|---|---|---|---|
| Tempra 12 | Trend | 12 | 50 | 1 x 50 DP | 1 x 8/2 AWG | 0.94 | 13.5 lbs | Order Tempra 12 Trend |
| Tempra 12 | Plus ✓ AFC | 12 | 50 | 1 x 50 DP | 1 x 8/2 AWG | 0.94 | 13.5 lbs | Order Tempra 12 Plus |
| Tempra 15 | Trend | 14.4 | 2 x 30 | 2 x 30 DP | 2 x 10/2 AWG | 0.96 | 16.1 lbs | Order Tempra 15 Trend |
| Tempra 15 | Plus ✓ AFC | 14.4 | 2 x 30 | 2 x 30 DP | 2 x 10/2 AWG | 0.96 | 16.1 lbs | Order Tempra 15 Plus |
| Tempra 20 | Trend | 19.2 | 2 x 40 | 2 x 40 DP | 2 x 8/2 AWG | 0.97 | 16.1 lbs | Order Tempra 20 Trend |
| Tempra 20 | Plus ✓ AFC | 19.2 | 2 x 40 | 2 x 40 DP | 2 x 8/2 AWG | 0.97 | 16.1 lbs | Order Tempra 20 Plus |
| Tempra 24 | Trend | 24 | 2 x 50 | 2 x 50 DP | 2 x 8/2 AWG | 0.97 | 16.1 lbs | Order Tempra 24 Trend |
| Tempra 24 | Plus ✓ AFC | 24 | 2 x 50 | 2 x 50 DP | 2 x 8/2 AWG | 0.97 | 16.1 lbs | Order Tempra 24 Plus |
| Tempra 29 | Trend | 28.8 | 3 x 40 | 3 x 40 DP | 3 x 8/2 AWG | 0.98 | 19.0 lbs | Order Tempra 29 Trend |
| Tempra 29 | Plus ✓ AFC | 28.8 | 3 x 40 | 3 x 40 DP | 3 x 8/2 AWG | 0.98 | 19.0 lbs | Order Tempra 29 Plus |
| Tempra 36 | Trend | 36 | 3 x 50 | 3 x 50 DP | 3 x 8/2 AWG | 0.98 | 19.0 lbs | Order Tempra 36 Trend |
| Tempra 36 | Plus ✓ AFC | 36 | 3 x 50 | 3 x 50 DP | 3 x 8/2 AWG | 0.98 | 19.0 lbs | Order Tempra 36 Plus |
✓ AFC = Advanced Flow Control — exclusive to Plus series. Trend series does not include Advanced Flow Control.
Temperature rise and flow rate by model
The Tempra's output capacity is determined by kW and temperature rise required. The higher the temperature rise, the lower the available GPM. Use this table — confirmed from the official Stiebel Eltron spec sheet — to select the right model based on your installation location and peak demand:
| Model | Temp rise at 1.5 GPM | Temp rise at 2.25 GPM | Temp rise at 3.0 GPM | Temp rise at 4.5 GPM |
|---|---|---|---|---|
| Tempra 12 | 54°F | 36°F | 27°F | — |
| Tempra 15 | 65°F | 43°F | 33°F | — |
| Tempra 20 | 88°F | 58°F | 44°F | 29°F |
| Tempra 24 | 92°F | 73°F | 54°F | 37°F |
| Tempra 29 | 92°F | 87°F | 66°F | 44°F |
| Tempra 36 | 92°F | 92°F | 82°F | 55°F |
Applies to both Trend and Plus series — temperature rise performance is identical between the two series at the same kW rating. To use this table: determine your required temperature rise (incoming ground water temperature subtracted from desired outlet temperature of 120°F), then find the model that achieves that rise at your peak GPM demand. The average US ground water temperature is 55°F — a 65°F rise to reach 120°F is the standard sizing benchmark for most of the country.
Sizing example — 55°F ground water, 65°F rise needed. At 2.25 GPM (one shower), the Tempra 20 achieves a 58°F rise — close but short. The Tempra 24 achieves a 73°F rise at 2.25 GPM — the right model. At 3.0 GPM (one shower plus a faucet), the Tempra 24 achieves a 54°F rise — right at the threshold. For two simultaneous showers at 55°F ground water, spec the Tempra 29 (66°F rise at 3.0 GPM) or Tempra 36.
Electrical requirements — plan before rough-in
The Tempra's electrical requirements are the most important installation planning factor. The larger models draw significant amperage and require dedicated circuits with appropriate wire gauge and breaker sizing. Confirm the electrical panel has capacity for the required circuits before the installation is scheduled.
- All models require 240V single phase — not 120V
- Copper conductors with a temperature rating of 75°C or greater required
- Tempra 12 — 1 x 50A double-pole breaker, 1 run of 8/2 AWG
- Tempra 15 — 2 x 30A double-pole breakers, 2 runs of 10/2 AWG
- Tempra 20 — 2 x 40A double-pole breakers, 2 runs of 8/2 AWG
- Tempra 24 — 2 x 50A double-pole breakers, 2 runs of 8/2 AWG
- Tempra 29 — 3 x 40A double-pole breakers, 3 runs of 8/2 AWG
- Tempra 36 — 3 x 50A double-pole breakers, 3 runs of 8/2 AWG
- Always confirm local code requirements before finalizing the electrical design
Key features — all Tempra models
- No gas line required — 240V electrical and a cold water supply line only
- No venting required — install anywhere in the home without flue or exhaust considerations
- 99% efficiency with zero standby heat loss — energy is consumed only when hot water is drawn
- Copper sheathed heating elements in copper cylinders — German engineering, proven long-term durability
- Microprocessor temperature control — constantly monitors flow rate and incoming water temperature, adjusts power to maintain precise output temperature
- Electronic flow switch — virtually silent activation
- Digital temperature display — front-mounted, easy to read and adjust
- Temperature range — 68°F to 140°F, factory set at 120°F
- Thermal cutout with manual reset — interrupts power at 185°F, prevents element damage from dry firing
- Seismic proof construction
- Tankless design prevents Legionella bacteria growth — no stored water at risk temperature
- WQA certified against NSF/ANSI/CAN 372 — lead-free compliance
- UL Std. 499 / CAN/CSA Std. C22.2 No. 88 certified
- Warranty — 7-year leakage / 3-year parts
- Advanced Flow Control (Plus series only) — patented, exclusive to Stiebel Eltron
Sizing quick reference by climate and bathroom count
| Climate / ground water | 1 bathroom | 2 bathrooms | 3+ bathrooms |
|---|---|---|---|
| Warm — 67°F–77°F ground water | Tempra 12 or 15 | Tempra 20 or 24 | Tempra 29 or 36 |
| Moderate — 52°F–62°F ground water | Tempra 15 or 20 | Tempra 24 or 29 | Tempra 36 |
| Cold — 37°F–47°F ground water | Tempra 20 or 24 | Tempra 29 or 36 | Tempra 36 + consult |
These are general guidelines — always confirm using the temperature rise table above with the actual peak GPM demand for the installation. High-flow showers, rain heads, or body spray systems increase peak GPM demand above the standard 2.0 GPM per shower benchmark and may require a larger model than the bathroom count alone suggests.
Frequently asked questions
What is the difference between the Tempra Trend and Tempra Plus?
Advanced Flow Control — exclusive to the Plus series. When demand exceeds capacity, the Plus automatically reduces flow slightly to maintain the set temperature. The Trend will deliver cooler water if demand exceeds capacity. Both series are otherwise identical in construction, efficiency, and warranty.
Does the Tempra require any venting?
No — the Tempra is a 100% electric unit with no combustion, no exhaust, and no venting requirements. It can be installed anywhere in the home with access to a 240V electrical connection and cold water supply.
What is the maximum output temperature?
140°F — the unit will not produce water above this temperature regardless of the temperature setting. Maximum inlet temperature is 131°F — the Tempra can also be used as a booster heater accepting preheated water up to 131°F.
What is the minimum flow to activate?
0.37 GPM for the Tempra 12, 0.50 GPM for the Tempra 15 through 24, and 0.77 GPM for the Tempra 29 and 36. Confirm all fixtures on the system meet the minimum activation flow for the model selected.
How many circuit breakers does the Tempra require?
Depends on the model — one double-pole breaker for the Tempra 12, two for the Tempra 15 through 24, and three for the Tempra 29 and 36. Confirm panel capacity before ordering.
Can the Tempra be used with 208V?
Yes — all Tempra models are rated for 208V single phase or unbalanced 3-phase in addition to 240V. At 208V, kW output is reduced — consult the spec sheet for 208V temperature rise figures which are lower than the 240V values shown above.
Is the Tempra suitable for commercial applications?
The Tempra is rated for whole house and multiple point-of-use applications. For large commercial applications requiring higher flow rates, contact our team — multiple units can be specified in parallel for increased capacity where the electrical infrastructure supports it.
Shop Stiebel Eltron Tempra at PlumbersCrib.com
All 12 Tempra models — Trend and Plus in every size — are available at PlumbersCrib.com. Use the table above to find the right model and click the order link to go directly to that product page. Contact our team or call 877-881-5501 Monday through Friday for help sizing the right Tempra model for your installation.