Our Best Electric Tankless Water Heater Reviews 2020 (+ Buying Guide)

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Unlike a traditional storage-type system, a tankless water heater does not store any hot water. Instead, the heating is instantaneous which provides for greater energy efficiency (up to 30%) due to the complete absence of standby losses.

Only paying for hot water that you are using will save you money in the long run. And that’s not all. You also get an endless supply of hot water, and a tankless water heater requires very little space.

Advantages that electric tankless water heaters have over gas units are they are cheaper to purchase & install, they operate more efficiently, they last longer, and you don’t have to worry about venting.

But how do you find the best electric tankless water heater? Well, picking a suitable unit requires some research. But don’t worry, we’ve got you covered!

On This Page You Will…

Top Rated Electric Tankless Hot Water Heaters Comparison List

ModelOur RatingPriceTypeElectricityEl. Service
Stiebel Eltron Tempra 24 Plus (220 V)

Best Tankless Electric Water Heater: Stiebel Eltron Tempra 24 Plus

Read Review
$$$$Whole House Model2x 12 kW2x 50 A Breakers
EcoSmart ECO 18 Electric Tankless Water Heater

Best Seller: EcoSmart ECO 18

Read Review
$$$Whole House Model2x 9 kW2x 40 A Breakers
Rheem RTEX-13 Mini Under Sink Unit

Best for Single Water Outlet: Rheem RTEX-13

Read Review
$$Point of Use Unit2x 6.5 kW1x 60 A Breaker
EcoSmart ECO 11 Electric Tankless System

Best Selling POU Water Heater: EcoSmart ECO 11

Read Review
$Point of Use Unit2x 5.5 kW1x 60 A Breaker
Stiebel Eltron DHC 3-1 Electric Tankless Under Sink Water Heater

Our #1 120 V (110 V) Heater: Stiebel Eltron DHC 3-1

Read Review
$Point of Use Unit1x 3 kW1x 25 A Breaker

Best Electric Tankless Water Heater Reviews

1. Number One Electric Tankless Water Heater on the Market: Stiebel Eltron Tempra 24 Plus (240 V)

Stiebel Eltron Tempra 24 Plus

Best Rated Electric Tankless Water Heater: Stiebel Eltron Tempra 24 Plus

  •    Price: $$$$
  •    Voltage: 240 V
  •    Temp. Range: 86-140 °F
  •    Power: 2x 12 kW
  •    El. Serv.: 2x 50 A Breakers

We will begin this electric tankless water heater reviews series with the best rated model currently on our list: The Stiebel Eltron Tempra 24 Plus, designed for whole home use (apartments are fine too) and light commercial applications.


Most importantly, how much hot water can the Tempra 24 Plus provide? Enough for up to 2 showers to run simultaneously:

  • Inlet/outlet water temperature 39/105 °F – 2.52 gallons per minute (gpm)
  • Inlet/outlet water temperature 59/105 °F – 3.63 gpm
  • Inlet/outlet water temperature 39/140 °F – 1.62 gpm
  • Inlet/outlet water temperature 59/140 °F – 2.02 gpm

Not enough water for your home? Well, the Stiebel Eltron Tempra line features many different units, some less and some more powerful than the 24 Plus. That being said, the 24 Plus is currently the most popular one.

Anyway, if your water needs are higher check out the 29 or 36 Plus. For example, the 36 Plus which is the largest unit supplies up to 5.45 gpm flow at 59 °F feed water and 105 °F output water temperature.

You have to keep in mind, though, that it requires 300 amps electrical service (3x 50A breaker) minimum, says Stiebel Eltron. The 24 Plus, on the other hand, requires only 2 separate dedicated 50A breakers and a minimum of 150A electrical service.

It’s probably best if you take a look at the sizing chart here.

But no matter which version you choose, all heaters have the same size and will deliver any water temperature between 86 to 140 °F – only at different flow rates.

You can use the large knob on the front cover for temperature control. Both °F and °C scales are available. By the way, the system is really quiet, and easy to use also thanks to the large backlit display that shows the output temperature.

More benefits:

  • Flow control technology regulates flow rate for accurate temperature delivery, so no “cold water surprises
  • Self-modulation ensures that least amount of energy is used at all times for maximum efficiency saving you money
  • Monitor shows cost savings
  • Stiebel Eltron tankless electric water heaters are some of the few on the market that are Made in Germany
  • 7 years warranted by manufacturer against leaking + 3 years against failure (requires product registration)
  • Expert customer support
  • Certified to ANSI/UL Standard 499 for the safety of electric heating appliances
  • Conforms to CAN/CSA E335-1 and E335-2-35, two Canadian standards also for the safety of household and similar electrical appliances
  • Tested and certified by the WQA against NSF/ANSI 372 for lead free compliance
  • EF is 0.99 – it doesn’t get much better

How about the installation?

Like we said, if you don’t know what you are doing, we definitely recommend you hire a licensed technician. In fact, the manual states that this water heater “must be installed by a licensed electrician and plumber“. Furthermore, “Failure to comply with the installation and operating instructions or improper use voids the warranty.

Customers that did install the system themselves said it was simple.

In terms of maintenance, it is recommended to remove scale and dirt that may build up at the screen in the cold water inlet from time to time – easy.


The Tempra Plus series has been extremely well received and there isn’t really much that we don’t like, except for the high price tag, of course.

Just a couple of issues that a handful of users had:

  1. For some the water heater lasted less than 2-3 years before one of the copper heating elements failed. We assume that this was mainly due to hard water scaling.
  2. Due to the Advanced Flow Control technology, you might only get a dribble at each outlet if you open too many at the same time. Automatically lowering the temperature slightly for compensation would make more sense.
  3. Water temperature can fluctuate even with just one shower running. This might have something to do with the minimum flow rate required for the system to activate (0.37 – 0.77 gpm depending on unit size). This also means that the heater might shut off when you turn down the water or lower the temperature.

Our Verdict: Ideal Choice to Meet Your Hot Water Needs

Stiebel Eltron’s Tempra Plus electric tankless water heaters, and the Tempra 24 Plus in particular, do exactly what they are supposed to do: Deliver continuous hot water whenever you need it. Excellent performance and large enough to meet the demand of all hot water applications of an entire home. This is one of the best electric tankless water heaters out there and definitely our number one. 4.5 stars!

2. Best Selling Electric Tankless Water Heater: EcoSmart ECO 18 (240 V)

EcoSmart ECO 18

Best Seller: EcoSmart ECO 18

  •    Price: $$$
  •    Voltage: 240 V
  •    Temp. Range: 80-140 °F
  •    Power: 2x 9 kW
  •    El. Serv.: 2x 40 A Breakers

Next, we are going to take a look at a best selling model at the time of writing this guide, namely the EcoSmart ECO 18 whole house electric tankless water heater.


Just like the Stiebel Eltron Tempra reviewed above, the EcoSmart ECO is available in a variety of sizes. The main difference between the two water heater series, however, is that the latter is a lot cheaper.

ECO 18, 24, 27 and 36 is what the manufacturer recommends for larger apartments, condominiums or townhomes.

Being the most popular unit, the ECO 18 might not be able to provide enough water for two showers, but maybe one shower + one faucet, depending on where you live in the country:

  • Inlet/outlet water temp 39/105 °F – 1.9 gpm flow rate*
  • Inlet/outlet water temp 59/105 °F – 2.7 gpm flow rate*


Now, this might not be enough water for your family’s needs. In this case, there is the larger EcoSmart ECO 27 or ECO 36. The latter can provide up to 5.3 gallons per minute flow (estimated) at 59 °F input water temp and 3.7 gpm at 39 °F.

For more info, check out the sizing chart included in the product description.

System size has no effect on the min/max temperature that you can set. The lower end is 80 °F, the upper end 140 °F. Simply use the large front knob for temperature control in 1-degree increments – child’s play!

What’s more, the self-modulating feature allows all ECO water heaters to adjust their energy input based on your actual hot water needs. In other words: No more energy is used than necessary for the current demand. Good for the environment and your wallet.

One advantage that this water heater has over the Stiebel Eltron Tempra is that it activates at 0.25 gpm water flow rather than 0.5 gpm. This means that it’s not as sensitive and won’t shut off producing a cold water rush if you slightly turn down the hot water when taking a shower.

And last but not least, we have an UL Standard 499 safety certification, an ETL listing, and all EcoSmart ECO electric water heaters are tested and certified against NSF Standard 372 for lead-free compliance.

Limited lifetime warranty? Check! (Requires registration within 30 days of purchase + installation by licensed professional)


Browsing dozens of customer reviews we stumbled upon 2 issues, although both were quite rare:

  1. Leaking
  2. The water heater simply stopped producing hot water or died

And while some reviewers said that tech support was “easy to reach” and replacement parts were shipped promptly, some complained that they could not get hold of a service representative or that they were difficult to work with.

Another difference to the Tempra is that EcoSmart ECO heaters are manufactured in China. Tempras are Made in Germany.

Our Verdict: Good Value for the Money

For most users, the EcoSmart ECO 18 and its siblings have been doing great: Consistently hot water combined with great energy savings. On top of that, the price is hard to beat. 4 stars!

3. Popular Whole Home Electric Tankless Water Heater Alternative: Rheem

Rheem RTEX-18

Rheem RTEX-18 Water Heater

  •    Price: $$$
  •    Voltage: 240 V
  •    Temp. Range: 80-140 °F
  •    Power: 2x 9 kW
  •    El. Serv.: 2x 40 A Breakers


Next on our list is the Rheem RTEX-18 electric tankless water heater. It’s a popular alternative to the EcoSmart providing 2 gpm at a temperature increase of 62 °F, 3 gpm at 41 °F, and 1.5 gpm at 82 °F. This makes it comparable to the EcoSmart ECO 18.

One difference, however, is that self-installation does not void the 5 year limited warranty. So if you know what you are doing you can save a few hundred bucks!

Other than that, not a lot new to say. We have the standard features: 80-140 °F temperature range (increments of 1 °F) which can be easily adjusted using the dial control. The system is self-modulating, meaning it uses no more energy than needed to meet you hot water demand. And we have an ETL listing, UL standard certification and one certification for lead-free compliance – this is about as safe as it gets.

Actually, there is one more thing: The Rheem RTEX-18 is the most stylish water heater in case that’s something you care about.

On a side note, another popular model is the RTEX-24. It’s a little bit bigger than the RTEX-18 and thus can supply more hot water in the same amount of time.


Reportedly, a few issues with leaks here and there and 2 or 3 systems that failed – nothing out of the usual.

We also read about problems with warranty claims.

Our Verdict

The Rheem RTEX-18 works exactly as advertised, nothing more and nothing less. As long as you pay attention to the right size it’s unlikely that you will experience any problems. Taking into account the higher price tag, we rate it with 4 stars.

4. Best Electric Water Heating Unit for Single Outlet: Rheem RTEX-13

Rheem RTEX-13

Best Single-Outlet Electric Tankless Water Heater: Rheem RTEX-13

  •    Price: $$
  •    Voltage: 240 V
  •    Temp. Range: 80-140 °F
  •    Power: 2x 6.5 kW
  •    El. Serv.: 1x 60 A Breaker

Let’s continue this guide with a bunch of point-of-use electric tankless water heaters, such as the Rheem RTEX-13.


Wait, Rheem RTEX-13? This sounds pretty familiar…

You are right! This is the smaller version of the RTEX-18 from before. So it comes with all the same features such as self-modulation technology for energy savings and an intuitive control panel (read more above).

How much hot water are we talking about? About one to one and a half gallons per minute, depending on incoming water temperature, so not a whole lot but enough for one faucet and to shower without fluctuation.


It seems like there are slightly more issues with the newer version such as random leaking.

Our Verdict

Not an entire household, but a single bathroom or kitchen faucet, or a weekend cabin is what the Rheem RTEX-13 tankless heater was designed for. Highly efficient, super space saving (fits literally anywhere) and stylish. All in all, a unit that provides great value – 5 stars!

5. Best Selling POU Water Heater on the Market: EcoSmart ECO 11

EcoSmart ECO 11 Instantaneous Under Sink System

EcoSmart ECO 11

  •    Price: $
  •    Voltage: 240 V
  •    Temp. Range: 80-140 °F
  •    Power: 2x 5.5 kW
  •    El. Serv.: 1x 60 A Breaker


The EcoSmart ECO 11 on demand water heater is another familiar face. Again, it shares the same features as all units that are part of the EcoSmart ECO series (learn more here).

But since this is a much smaller heater, the hot water supply is significantly lower:

  • Inlet/outlet water temperature 39/105 °F – 1.3 gpm flow*
  • Inlet/outlet water temperature 59/105 °F – 2.0 gpm flow*


All in all, the EcoSmart ECO 11 model is ideal for one bathroom or one kitchen sink and in cooler climates perfect for a low-flow faucet.


As mentioned before, rare issues include leaking or systems that just stopped producing hot water. Opinions about the EcoSmart customer service are mixed.

Our Verdict

Compact design, user-friendly, and tad more affordable than the Rheem RTEX-13 but at the same time a little less well received. 4.5 stars for this unit!

6. Cheap 240 V System (2 Colors): ECOTOUCH



  •    Price: $
  •    Voltage: 240 V
  •    Max. Temp.: 130 (131) °F
  •    Power: 1x 5.5 kW
  •    El. Serv.: 1x 30 A Breaker


The ECOTOUCH is a budget point-of-use tankless electric water heater that runs on 240 volt.

5.5 kW are enough to heat 1.2 gallons from 67 °F to 109 °F. In other words: The unit is mainly for sinks, not for showers.

Black or white – the modern, compact design is futuristic and attractive, also thanks to the led display with an integrated touch panel for easy temp setting (one degree accuracy).

Alternatively, you can use the remote control to turn the system on/off and control water temperature.

Speaking of, the hot water heater adjusts electricity input based on flow rate and temperature settings in real time. When water flow is reduced, the system applies less power and vice versa. This allows for the most stable temperature management and it makes the unit highly energy efficient.

ETL safety approval and UL qualified for peace of mind? Check!

Fits anywhere and the installation is very simple, too.


We have one concern and that is the minimum required water flow for the unit to activate: 0.475 gpm is quite a lot. It could mean that the ECOTOUCH might not turn on (or turn off!) when you are not using enough hot water.

Our Verdict: Great Electric Tankless Water Heater for Low-Flow Applications

Keep in mind that the ECOTOUCH is for low-flow applications – think small faucet. We mention this because some people complained that they did not get very hot water in their shower which is not the system’s fault. All in all, solid performance and highly affordable. 4 stars!

7. Our Favorite 120 V Electric Tankless Water Heater: Stiebel Eltron DHC 3-1

Stiebel Eltron DHC 3-1 In-Line Electric Tankless Water Heater

Stiebel Eltron DHC 3-1

  •    Price: $
  •    Voltage: 110/120 V
  •    Temp. Range: -
  •    Power: 1x 3 kW
  •    El. Serv.: 1x 25 A Breaker


The Stiebel Eltron’s DHC 3-1 might be last on our list, however, it is our number one solution when it comes to small electric tankless water heaters that run on 120 respectively 110 volt.

Bathroom or kitchen, this is a single sink unit, mind you. At 0.43-1.14 gpm water flow rate, it won’t provide enough hot or warm water for showering.

This is also why the DHC 3-1 gets shipped with an aerator for pressure compensation that fits most faucets.

More features? Yes! The water heater is inexpensive, made in the USA according to German engineering, and includes a 7-year warranty against leakage and 3 years against defects in workmanship & materials through the manufacturer.

All safety standards are followed.


For one, the DHC 3-1 didn’t last very long for some people, between a few weeks and up to 10 months. At least the tech support is great.

Secondly, not everyone could get a steady stream of hot water. This might have to do with the minimum flow rate required for activating the heater (0.32 gpm).

And lastly, you can’t adjust output temperature according to your needs. It’s controlled by input temp and flow rate alone which can be inconvenient.

Our Verdict: Perfect Electric Tankless Water Heater for Small Spaces

Here we have a top rated low-volt electric tankless water heater that, compared to other units on the market, is reasonably priced and works as advertised. Perfect for small spaces. 4 stars!

Buying Guide – What to Consider When Buying an Electric Tankless Water Heater

Products, products everywhere… So what to consider when buying a quality electric tankless water heater for your home?

First of all, whether you call them tankless water heaters, on demand water heaters, instant water heaters or instantaneous electric water heaters, they all describe the same thing: Water is heated only when needed.

Sizing Electric Tankless Water Heaters

Choosing a tankless electric water heater always starts with sizing.

Your ideal system size depends on how many people live in your home, their water using habits, and also how many bathrooms and hot-water appliances you have.

Simply put, small, medium or large depends on how much hot water your household needs at times of peak consumption. If you go too small you might have saved some space but the amount of hot water will be limited, so you either have to use less or it won’t be as warm. Going way too large means overspending.

We also have to differentiate between POU units and POE units. The former supply a single outlet, for example a bathroom faucet. The latter heat the water of an entire household.

Another very important factor when sizing electric tankless water heaters is where you live in the country which translates to incoming water temperature. Because if you live in a colder climate the temperature rise that’s needed is naturally higher.

The southern states have warmer input water, but if you live in the north and it’s winter, you might not be able to run two showers without experiencing a loss in temperature or flow rate.

So as a general rule, the farther north you live, the larger a home water heating system you need.

woman in hot shower

Electric Tankless Water Heater Installation

First of all, the average DIYer might say that installing an electric tankless water heater is simple. However, if you don’t know what you are doing you should definitely not try to do this yourself just to save a few bucks. It’s simply too dangerous and not worth the risk.

As a matter of fact, with some manufacturers their heaters must be installed by licensed contractors or else the warranty will void.

Another thing to bear in mind is that not every home is suited for a POE unit, simply because the amp draw would be too high. This could mean that your old electrical service panel needs bigger wires and bigger breakers, or you have to run a completely new one entailing a couple of thousand dollars worth of electrical work.


Tankless water heaters last much longer than regular tank heaters with proper maintenance. 15 to 25 years can be reasonable if you make sure to delime regularly. Deliming means to remove possible scale residues that stick to the (copper) heating elements when they are used to heat hard water.

Another option would be to install a water softener upstream of the heater.


What about energy efficiency? Well, it turns out that this plays a minor role when electric tankless water heaters that run on electricity, since they are all highly energy efficient (at least 95 percent).

For more information you can refer to a system’s Energy Factor (EF). It rates the energy conversion efficiency. Products rated at a higher factor means they are more energy efficient so that less energy is wasted.


Some people pay attention to this, some don’t. We consider the design of a unit a secondary factor, although a quality design can provide value in itself.


One needs enough space to accommodate a tankless water heater in his or her household. Heaters feeding a single outlet fit almost anywhere, in a bathroom cabinet for example. POE models are not for super tight spaces.

More on Electric Tankless Water Heaters

Frequently Asked Questions (FAQ)

  • Do electric tankless water heaters need venting?
    No, they don’t. Venting is only required with gas water heaters.
  • Is it hard to install an electric tankless water heater?
    Skilled DIYers might say it’s simple. However, if you don’t know what you are doing you shouldn’t try. It’s too dangerous. Also, some on demand units must be installed by a licensed contractor or else the manufacturer warranty will void.
  • How many amps does an electric tankless water heater draw?
    The lowest draw we could find was 14 A for a low flow POU unit. POE systems can go as high as 150 A.
  • How energy efficient are electric tankless water heaters?
    The technology is highly efficient, at least 95%. The best electric water heater on the market reaches 99.8%.
  • How much does it cost to run an electric tankless water heater?
    Annual cost ranges from less than $100 USD up to $300 USD and higher.
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Questions about our home electric tankless water heaters list? Ask away!

And make sure to come back to this page from time to time as we might find the next best electric tankless water heater soon!

About the Author Gene Fitzgerald

Gene Fitzgerald has been with BOS since the very beginning. She is head of content creation and has fully immersed herself into the home water treatment industry only to become an expert herself. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
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