The Stiebel Eltron Tempra 36 Plus is the clear frontrunner for whole-home electric tankless heating, good for up to 7.5 GPM from its 36 kW heating element. This Old House rated the Stiebel Eltron electric line 4.4/5, and Bob Vila named it best electric, both praising the silent operation and the Advanced Flow Control that dynamically reduces flow rather than letting cold-water sandwiching happen when demand exceeds capacity. It needs serious electrical service and performs best in moderate climates. For an all-electric home, it is the top whole-house pick.
Full review
Whole-Home Electric Done Right
Electric tankless units historically struggled to supply a whole house, but the Tempra 36 Plus is the exception that makes it work. Its 36 kW element delivers up to 7.5 GPM — enough, as Reviewed put it, to 'easily accommodate four or more appliances and fixtures operating simultaneously.' This Old House rated the Stiebel Eltron electric line 4.4/5 and praised that it ensures 'ongoing energy savings without requiring venting,' and Bob Vila named it best electric, highlighting its silent operation. For an all-electric home that wants whole-house tankless heating, this is the unit reviewers reach for first.
Advanced Flow Control
The Tempra's standout feature is Advanced Flow Control. When hot-water demand exceeds what the unit can heat — say, two showers plus the dishwasher on a cold day — it briefly reduces flow rather than letting the temperature crash. That eliminates the 'cold-water sandwich' that plagues lesser electric units, where you get a slug of cold water mid-shower. It's a genuinely differentiating bit of engineering that neither the EcoSmart ECO 27 nor the Rheem RTEX-13 matches, and it's a big reason the Tempra earns its best-electric billing.
Paired with self-modulating power that draws only the energy needed to hit the set temperature, the result is consistent hot water and efficient operation, without the standby losses of a tank.
Silent, Clean Operation
Because it's electric, the Tempra has no combustion — which means no venting, no gas line, no carbon-monoxide risk, and, as Bob Vila noted, genuinely silent operation. That makes installation simpler in some respects than a gas condensing unit and opens up placement options, since you don't need to route exhaust. The compact, wall-mounted German design is unobtrusive and well-built, the kind of appliance you install and forget.
The strongest flow rate among electric units
Across This Old House, Bob Vila, and Reviewed, the praise is consistent: strong flow rate for an electric unit, the smart Advanced Flow Control, silent and clean operation, and solid efficiency. Reviewers repeatedly frame it as the electric unit to buy when you want whole-home capability rather than a single point of use. Its 4.4-4.5 ratings reflect a unit that does the hard electric-tankless job better than its rivals.
Its 36kW draw often needs a panel upgrade
The Tempra 36 Plus is power-hungry. At 36 kW it demands substantial electrical service, and many homes will need an electrical panel upgrade and heavy-gauge wiring to support it — a real installation cost. Its flow rate also drops as the required temperature rise increases, so in cold-climate regions with frigid inlet water it can't match its warm-climate numbers; professionals generally note electric tankless units perform best in the southern U.S. And being electric, it doesn't qualify for the gas tankless federal tax credit that the Rinnai and Takagi do.
Whole-house hot water without gas or venting
Choose the Stiebel Eltron Tempra 36 Plus if you have an all-electric home in a moderate or warm climate and want whole-house tankless hot water without gas or venting. It's the best electric unit for handling multiple fixtures at once. If you're in a cold climate with high temperature-rise demands, a gas unit like the Rinnai RU199iN will hold flow better; if your needs are smaller, the EcoSmart ECO 27 or point-of-use Rheem RTEX-13 cost far less to buy and power.
The only electric option for a whole house
The Tempra 36 Plus sits in the middle of this group on price, well below the gas units once you account for venting and gas-line work, but above the smaller electric heaters. Its value proposition is being the only electric unit here that can credibly run a whole home, so for an all-electric house it often has no real competitor short of jumping to gas. Factor in the likely cost of an electrical panel upgrade, though, because at 36 kW the wiring requirements are real and can erase some of the apparent savings over a gas install. Where it pays off is over time: no venting to maintain, no combustion, no annual gas safety considerations, and the efficiency of heating only on demand. For the right home, it's the most sensible long-term electric investment in this lineup.
Strengths
- +Best whole-home electric option, up to 7.5 GPM at 36 kW
- +Advanced Flow Control throttles flow to prevent cold-water sandwiching
- +Silent operation with no combustion, venting, or CO risk
- +Self-modulating power uses only the energy needed
- +Compact, wall-mounted German engineering
Watch-outs
- −Needs substantial electrical service — often a panel upgrade
- −Flow rate drops in cold climates with high temperature rise
- −No federal gas tax credit (electric)
- −Best suited to warmer or moderate regions
How it compares
The Stiebel Eltron Tempra 36 Plus is the best whole-home electric unit, with a 7.5 GPM flow rate that beats the EcoSmart ECO 27 and Rheem RTEX-13 but trails the gas Rinnai RU199iN and Takagi T-H3-DV-N. Its Advanced Flow Control is a feature neither the EcoSmart nor the Rheem offers, trading a brief flow reduction for consistently hot water.
Rating sources
“ensure ongoing energy savings without requiring venting”
“Silent operation”
“At a flow rate of up to 7.5 gallons per minute, this heater can easily accommodate four or more appliances and fixtures operating simultaneously.”
Our 4.5 score is the average of these published ratings. Ratings marked * were derived from the reviewer’s written analysis or video transcript — the publisher didn’t print an explicit numeric score, so we inferred one from their own words. Click through to verify. More about methodology.
