Tempra Plus vs. Tempra Trend: What the Plus Adds
A Tempra Plus and a Tempra Trend of the same size draw the same power and deliver the same flow at a given temperature rise. Here's what the Plus adds, with breaker and flow tables for all six sizes.
In this guide
Stiebel Eltron's installation manual lists the Tempra Plus and Tempra Trend side by side, size by size, in its technical data and flow tables. They draw the same power, take the same breakers and wire, and deliver the same flow at a given temperature rise.
The difference is in the controls. The Plus adds Advanced Flow Control, two preset temperature buttons, a second display line that shows the flow rate, and an information menu with an estimate of your savings.
What both series share
Both series come in six sizes: 12, 15, 20, 24, 29 and 36. A Tempra 29 Trend and a Tempra 29 Plus have the same electrical and flow ratings, and the same goes for every other size.
- Setpoint from 68°F to 140°F, set with the knob on the front cover.
- Self-modulation: sensors read the incoming water temperature, the flow and the outlet temperature, and the control switches the heating elements in stages to hold the setpoint.
- A Tmax setting that caps how high anyone can turn the setpoint, and a display lock.
- No venting needed.
- The same dimensions on every size: 14-1/2 in. high, 16-5/8 in. wide, 4-5/8 in. deep, with 3/4 in. NPT water connections.
What the Plus adds
Advanced Flow Control
When more hot water is drawn than the heater can supply, Advanced Flow Control reduces the flow slightly so that the water still leaves at the set temperature. Stiebel Eltron lists it on the Plus only.
Tip A Trend doesn't have it. The manual's troubleshooting table, which covers both series, lists "water flow rate too high" as one cause of water that isn't hot enough; the fix is to reduce the flow until the power light on the front cover stops blinking.
Two preset buttons
Preset 1 and Preset 2 each store a temperature. One press changes the setpoint to the stored value.
Second display line
The lower half of the Plus display shows the current flow in gpm or l/min. The Plus information menu shows the estimated accumulated cost savings compared with a tank-type water heater, based on the electricity rate per kWh you enter.
The Plus also reports error codes: when it detects an error, a wrench symbol lights up and the Information button brings up the code.
| Feature | Trend | Plus |
|---|---|---|
| Setpoint 68–140°F | Yes | Yes |
| Self-modulation | Yes | Yes |
| Tmax setting, display lock | Yes | Yes |
| Advanced Flow Control | No | Yes |
| Preset buttons | No | 2 |
| Flow rate on display | No | Yes |
| Cost savings estimate | No | Yes |
| Error code display | Not listed | Yes |
Stiebel Eltron's Tempra Trend product page mentions a memory preset; the manual and the brand's comparison chart show preset buttons on the Plus only.
Power and breakers by size
These figures apply to Trend and Plus alike, at 240 V. The 29 and 36 need three separate circuits, each on its own double-pole breaker.
| Size | Power | Min. breakers | Min. main service |
|---|---|---|---|
| 12 | 12 kW | 1 × 50 A | 100 A |
| 15 | 14.4 kW | 2 × 30 A | 100 A |
| 20 | 19.2 kW | 2 × 40 A | 125 A |
| 24 | 24 kW | 2 × 50 A | 150 A |
| 29 | 28.8 kW | 3 × 40 A | 200 A |
| 36 | 36 kW | 3 × 50 A | 300 A |
Breakers are the manual's minimum recommended double-pole sizes. The main service figures are Stiebel Eltron's recommended minimums and depend on the total electric load at the site.
Wire is copper rated 75°C or higher; the manual's minimum recommended wire size is 8/2 AWG for every size except the 15, which takes 10/2 AWG. Stiebel Eltron adds that conductors should be sized to keep voltage drop below 3% under load, and to check local codes for compliance if necessary.
Hot water flow by size
Flow depends on how much the heater has to raise the water temperature. This table is for 105°F at the outlet at 220–240 V, from the manual's flow table.
| Size | 39°F inlet | 59°F inlet |
|---|---|---|
| 12 | 1.26 gpm | 1.82 gpm |
| 15 | 1.51 gpm | 2.18 gpm |
| 20 | 2.02 gpm | 2.91 gpm |
| 24 | 2.52 gpm | 3.63 gpm |
| 29 | 3.03 gpm | 4.36 gpm |
| 36 | 3.78 gpm | 5.45 gpm |
The heater needs a minimum flow to turn on: 0.37 gpm (12), 0.5 gpm (15, 20, 24) or 0.77 gpm (29, 36).
On 208 V
Warning Every size puts out less power on single-phase 208 V. The 29, for example, drops from 28.8 kW to 21.6 kW. Stiebel Eltron's sizing guide is based on 240 V installations and says to go up one model for 208 V.
The 29 and 36 may also be wired for balanced three-phase 208 V, and the 15, 20 and 24 for unbalanced three-phase 208 V.
Picking a series
Size comes first: it sets the flow at a given temperature rise, and it's the same choice in either series. Our guide to what size electric tankless water heater you need walks through Stiebel Eltron's sizing chart by incoming water temperature. Then pick the series by the controls.
- Pick the Plus if demand may exceed the heater's capacity. Advanced Flow Control then reduces the flow slightly so the water stays at the set temperature.
- Pick the Plus if you want presets, a flow readout or error codes on the display.
- Pick the Trend if the knob, Tmax setting and display lock are all the controls you need. Its power, flow and self-modulation match the Plus of the same size.
We carry the Tempra 12 Trend, the Tempra 29 Plus and the Tempra 36 Plus. Our other HVAC and plumbing products are in HVAC, Plumbing & Water Heating.
FAQ
What are the electrical requirements for a Tempra 29 Plus?
At 240 V it draws 28.8 kW on three circuits. The manual's minimum recommended sizes are three 40 A double-pole breakers and three runs of 8/2 AWG copper wire rated 75°C or higher. Stiebel Eltron adds that conductors should be sized to keep voltage drop below 3% under load, and to check local codes for compliance if necessary. Stiebel Eltron recommends a main service of at least 200 A, depending on the total load at the site. The Tempra 29 Trend has the same requirements.
Does the Tempra 36 Plus have Advanced Flow Control?
Yes. Every Tempra Plus has it, and no Tempra Trend does.
Specifications come from Stiebel Eltron's Tempra Trend & Tempra Plus installation and operating manual, the Tempra Trend and Tempra Plus product pages, the brand's Trend vs. Plus comparison chart and the Tempra sizing guide. The manual says the Tempra has no parts the average user can service. It must be installed by a licensed electrician and plumber, and for a malfunction the manual says to contact a licensed plumber or electrician.
