7 Best Electric Tankless Water Heaters: Reviews + Guide 2021

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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’re 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-powered units are: They are cheaper to purchase & install, they operate more efficiently, they last longer, and you don’t need 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…

No Time to Read? Check Our List of the Best Electric Tankless Water Heaters!

Water HeaterDetails
Stiebel Eltron Tempra 24 Plus (220 V) Whole House Electric Tankless Water Heater
Best Whole House Electric Tankless Water Heater: Tempra 24 Plus

Read Review

Price: $$$
Temp: 86-140 °F
Power: 2x 12 kW
Electrical Service: 2x 50 A Breakers
EcoSmart ECO 18 Electric Tankless Water Heater
Whole House Alternative: EcoSmart ECO 18

Read Review

Price: $$$
Temp: 80-140 °F
Power: 2x 9 kW
Electrical Service: 2x 40 A Breakers
Rheem RTEX-13 Mini Under Sink Electric Tankless Water Heater
Best Electric Tankless Water Heater for Point of Use: Rheem RTEX-13

Read Review

Price: $$
Temp: 80-140 °F
Power: 2x 6.5 kW
Electrical Service: 1x 60 A Breaker
EcoSmart ECO 11 Electric Tankless System
Point-of-Use Alternative: EcoSmart ECO 11

Read Review

Price: $
Temp: 80-140 °F
Power: 2x 5.5 kW
Electrical Service: 1x 60 A Breaker
Stiebel Eltron DHC 3-1 Electric Tankless Under Sink Water Heater
#1 120V Water Heater: Stiebel Eltron DHC 3-1

Read Review

Price: $
Temp: ?
Power: 1x 3 kW
Electrical Service: 1x 25 A Breaker

Best Electric Tankless Water Heater Reviews

1. Our #1 Whole House Electric Tankless Water Heater: Stiebel Eltron Tempra 24 Plus (240 Volts)

In our opinion, the best whole house electric tankless water heater in 2021 is the Stiebel Eltron Tempra 24 Plus (apartments and light commercial applications work, too).

Stiebel Eltron’s Tempra Plus electric tankless water heater series, 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 high flow meet the demand of all hot water applications of an entire household. Definitely our number one! 4.5 stars!

Stiebel Eltron Tempra 24 Plus Whole House Electric Tankless Water Heater

Tempra 24 Plus

Price:$$$
Voltage:240
Temp. Range:86-140 °F
Power:2x 12 kW
Electrical Service:2x 50 A Breakers

Our Rating

Pros

  • The Tempra 24 Plus provides enough water for up to 2 showers running simultaneously:
    • 39/105 °F inlet/outlet water temp: 2.52 gallons per minute (gpm).
    • 59/105 °F inlet/outlet water temp: 3.63 gpm.
    • 39/140 °F inlet/outlet water temp: 1.62 gpm.
    • 59/140 °F inlet/outlet water temp: 2.02 gpm.
  • Stiebel Eltron’s Tempra line also features smaller and larger units. Just pick one that fits the size of your home best.
    • If your water needs are higher, check out the Tempra 29 or 36 Plus. The 36 Plus is the largest unit and supplies up to 5.45 gpm at 59 °F feed water and 105 °F output water temperature. Keep in mind, though, that it requires 300 amps electrical service (3x 50A breaker) minimum, says Stiebel Eltron.
    • It’s probably best if you take a look at the sizing chart here.
  • No matter which version you choose, all heaters have the same size and deliver any water temperature between 86 to 140 °F – only at different flow rates.
  • Highly energy-efficient: EF is 0.99 – it doesn’t get much better.
  • Large knob on the front allows for simple temperature control. Both °F and °C scales are available.
  • System is really quiet and easy to use thanks to the large backlit display that shows output temperature.
  • Flow control technology regulates water flow rate for accurate temperature delivery. 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 Made in Germany.
  • Certified to ANSI/UL Standard 499 for the safety of electric heating appliances. Also conforms to CAN/CSA E335-1 and E335-2-35, two Canadian standards established for the safety of household and similar electrical appliances.
  • 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.
  • 7 years warranted by manufacturer against leaking + 3 years against failure (requires product registration).
  • Expert customer support.

Cons

  • Manual states 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.
  • For some users, 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.
  • The Advanced Flow Control technology might cause low flow if you open too many outlets at the same time. Automatically lowering the temperature slightly for compensation would make more sense.
  • 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 water heater could shut off when you turn down the water or lower the temperature.

2. Whole House Electric Tankless Water Heater Alternative: EcoSmart ECO 18 (240 V)

Just like the Stiebel Eltron Tempra reviewed above, the EcoSmart ECO is available in a variety of sizes to meet your water demand. The main difference between the two water heater series, however, is that the latter is far more affordable.

ECO 18, ECO 24, ECO 27, and ECO 36 is what the manufacturer recommends for larger apartments, condominiums, or townhomes. They combine consistently hot water with great energy savings. 4 stars!

EcoSmart ECO 18 Whole House Electric Tankless Water Heater

EcoSmart ECO 18

Price:$$$
Voltage:240
Temp. Range:80-140 °F
Power:2x 9 kW
Electrical Service:2x 40 A Breakers

Our Rating

Pros

  • 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.
  • In case this is not enough hot water for your family’s needs, there is the larger ECO 27 and the 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.
  • System size has no effect on the min/max temperature 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!
  • Self-modulating technology 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. Good for the environment and your wallet.
  • Advantage over the Tempra: System activates at 0.25 gallons per minute 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.
  • 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 (requires registration within 30 days of purchase + installation by licensed professional).

Cons

  • Reading reviews we stumbled upon 2 issues, although both were quite rare: Leaking, and the water heater simply stopped producing hot water or died.
  • Some reviewers said tech support was “easy to reach” and replacement parts were shipped promptly. Others complained they could not get hold of a service representative or that they were difficult to work with.

3. Our Number One Point-of-Use Electric Tankless Water Heater: Rheem RTEX-13

In our opinion, the best electric tankless water heater for point-of-use applications in 2021 is the Rheem RTEX-13.

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

Rheem RTEX-13 POU Electric Tankless Water Heater

Rheem RTEX-13

Price:$$
Voltage:240
Temp. Range:80-140 °F
Power:2x 6.5 kW
Electrical Service:1x 60 A Breaker

Our Rating

Pros

  • The RTEX-13 is the most stylish water heater in case that’s something you care about.
  • About 1 to 1.5 gpm depending on the incoming water temperature is sufficient for one faucet and showering without fluctuation.
  • We have the standard temperature range: 80-140 °F (increments of 1 °F) which can be easily adjusted using the dial control.
  • System is self-modulating, meaning it uses no more energy than needed to meet you hot water demand.
  • ETL listing, UL standard certification, and one certification for lead-free compliance – this is about as safe as it gets.
  • Self-installation does not void the 5-year warranty.
    • If you know what you are doing you can save a few hundred bucks!

Cons

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

4. Best Selling POU Water Heater Alternative: EcoSmart ECO 11

As an alternative to the Rheem RTEX-13, we like to recommend the EcoSmart ECO 11. It’s a tad more affordable, has a compact design, and is user-friendly. At the same time, it’s a little less well received. 4.5 stars for this unit!

EcoSmart ECO 11 Instantaneous Under Sink System

EcoSmart ECO 11

Price:$
Voltage:240
Temp. Range:80-140 °F
Power:2x 5.5 kW
Electrical Service:1x 60 A Breaker

Our Rating

Pros

  • The EcoSmart ECO 11 on-demand water heater is a familiar face. It shares the same features as all systems that are part of the ECO series. But since this is a much smaller heater, the hot water supply is significantly lower:
    • Inlet/outlet temperature 39/105 °F – 1.3 gpm.
    • Inlet/outlet temperature 59/105 °F – 2.0 gpm.
  • All in all, the ECO 11 model is ideal for one bathroom or one kitchen sink, and in cooler climates perfect for a low-flow faucet.
  • Large knob on front cover lets you easily adjust the temperature settings.
  • Energy use varies based on water usage to save energy costs.
  • UL and ETL listing for guaranteed safety.
  • EcoSmart offers lifetime warranty.

Cons

  • Rare issues include leaking or systems that just stopped producing hot water.
  • Opinions about the EcoSmart customer service are mixed.

5. Cheap: ECOTOUCH

Are you looking for something for smaller budgets? How about the ECOTOUCH? It’s 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!

ECOTOUCH Point-of-Use Electric Tankless Water Heater

ECOTOUCH

Price:$
Voltage:240
Temp. Range:130 (131) °F
Power:1x 5.5 kW
Electrical Service:1x 30 A Breaker

Our Rating

Pros

  • The ECOTOUCH is a budget point-of-use tankless electric water heater that runs on 240 volts.
  • 5.5 kW are enough to heat 1.2 gallons from 67 °F to 109 °F. So the unit is mainly for sinks, not 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).
  • You can also use the remote control to turn the system on/off and control water temperatures.
  • 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.
    • Allows for the most stable temperature management and makes the unit highly energy efficient.
  • ETL safety approval and UL qualified for peace of mind.
  • Fits anywhere + easy to install.

Cons

  • Our only concern is the minimum required 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.

6. Rheem RTEX-18 Whole House Tankless Electric Water Heater

Wait, Rheem RTEX-18? This sounds pretty familiar…

You are right! This is the larger version of the RTEX-13 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). One of the best electric tankless water heaters out there. 4 stars!

Rheem RTEX-18 Whole House Electric Tankless Water Heater

Rheem RTEX-18

Price:$$$
Voltage:240
Temp. Range:80-140 °F
Power:2x 9 kW
Electrical Service:2x 40 A Breakers

Our Rating

Pros

  • The RTEX-18 electric tankless water heater is a popular alternative to the EcoSmart, providing 2 gpm at a temperature increase of 62 degrees Fahrenheit, 3 gpm at 41 degrees Fahrenheit, and 1.5 gpm at 82 °F.
    • Comparable to the ECO 18.
  • 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.
  • Easy to use: Adjust output temperature using dial control.
  • Self-modulating technology prevents energy wastage.
  • ETL listing + UL standard certification guarantee the safety of this product.
  • Covered by 5-year limited warranty.
    • Does not void when self-installed.

Cons

  • 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.

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

Last in our electric tankless water heater reviews series: The Stiebel Eltron DHC 3-1, a 120 low-volt system perfect for small spaces. Compared to other units on the market, the DHC 3-1 is reasonably priced and works exactly as advertised. 4 stars!

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

Stiebel Eltron DHC 3-1

Price:$
Voltage:110/120
Temp. Range:?
Power:1x 3 kW
Electrical Service:1x 25 A Breaker

Our Rating

Pros

  • Made in USA according to German engineering.
  • 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. At 0.43-1.14 gpm water flow rate, it won’t provide enough hot or warm water for showering.
  • Gets shipped with an aerator for pressure compensation that fits most faucets.
  • All safety standards are followed.
  • Includes a 7-year warranty against leakage and 3 years against defects in workmanship & materials through the manufacturer.
  • Tech support is great.

Cons

  • The DHC 3-1 didn’t last very long for some people, between a few weeks and up to 10 months.
  • 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).
  • You cannot adjust output temperature according to your needs. It’s controlled by input temp and flow rate alone which can be inconvenient.

Electric On-Demand Water Heaters Comparison List

(Mobile Hint: Swipe to Scroll)

Heating SystemsPriceAdditional Info
Tempra 24 Plus Residential Tankless Water Heater$$$Best Value, High Flow for Larger Households, Digital Temperature Control + Advanced Flow Control, Digital Display
ECO 18 Residential Tankless Water Heater by EcoSmart$$$For Larger Households, 0.25 gpm Activation Flow, Digital Display
RTEX-13 Tankless Heater by Rheem$$Best Value for Heating Water, Relatively Easy to Install, Digital Display
ECO 11 Water Heating System by EcoSmart$Relatively Easy to Install, Digital Display
ECOTOUCH$0.475 gpm Activation Flow, Digital Display, Easy to Install
RTEX-18 Residential Tankless Water Heater by Rheem$$$Digital Display
Stiebel Eltron DHC 3-1$Saves Energy, Relatively Easy to Install, Digital Display

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

Sizing (Temperature Rise & Flow Rates)

Choosing a whole house 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 – e.g. dishwasher and washing machine – 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. On the other hand, going too large means overspending.

whole house electric tankless water heater

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

The southern states have warmer input water. But when it is winter and you’re in the north, you might not be able to run two hot showers without experiencing a drop in hot water pressure or lower water temperature.

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

Energy Efficiency

What about energy efficiency? Well, it turns out that this plays a minor role with electric tankless water heaters. That’s because they’re all highly energy efficient (at least 95 percent).

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

Design

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.

Compactness

One needs enough storage 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.

Convenience

You want a water heater that’s easy to use.

Most importantly, it should allow you to adjust output water temperature by turning a knob or pressing a button.

Electric Tankless Water Heater Installation

The average DIYer might say that installing an electric tankless water heater is simple. However, if you don’t know what you’re 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 water heaters must be installed by licensed contractors or else the warranty voids.

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 need to run a completely new one entailing a couple of thousand dollars worth of electrical work.

Maintenance

Tankless water heaters last much longer than regular storage 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/stainless steel) heating elements when they are used to heat hard water.

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

Warranty

It’s always nice to have a lifetime product warranty for peace of mind.

More on Electric Tankless Water Heaters

What is an Electric Tankless Hot Water Heater?

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

How does an electric tankless water heater work? They activate when they sense flow in the water line they’re installed at, for example when you open your kitchen faucet. Electricity flows through one or more heating elements which are in contact with the water. The water heats up and leaves the system all nice and warm.

Not storing any hot water means no standby losses which provides for greater energy efficiency. Plus, you can never run out of hot water.

By the way, we can categorize water heaters into whole house systems that provide an entire home and those designed for a single point of use.

Types of Electric Tankless Water Heaters

As mentioned above, we can differentiate between POU and POE tankless water heaters.

Point-of-Use Electric Tankless Water Heaters

POU electric tankless water heaters supply a single outlet with hot water, for example a bathroom faucet. They are small and fit almost anywhere such as a bathroom cabinet.

Point of Use Electric Tankless Water Heater in Shower

Whole House Electric Tankless Water Heaters

Whole house water heaters heat the water of an entire household. Therefore, POE models are not for super tight spaces.

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

Advantages of an Electric Tankless Water Heater

On-Demand Heating without Standby Losses

Tank water heaters heat the water and store it for later use. A tankless water heater is a demand-based system. Instantaneous heating provides for much higher energy efficiency due to the complete absence of standby losses.

At Least 95% Efficiency

If you do your research you’ll find that electric tankless heaters usually have an energy factor of 95 percent or higher. This means that at least 95% of all input energy is translated into heat. It doesn’t get any better than that!

Endless Hot Water on Demand

If a traditional heater’s water tank runs out of hot water, you run out of hot water. With a tankless system, you get and endless supply of hot water.

Flexible Installation

What we mean by flexible installation is that tankless electric water heaters are relatively small and fit in tight spaces.

No Need to Worry About Venting

Electric systems don’t require venting.

Lower Costs & Utility Bills

Tankless or not, electric hot water heaters are cheaper than gas-powered units in terms of initial cost and installation expenses.

Above that, you’ll save money by only paying for hot water that you actually use.

Longer Lifespan

Another advantage of electric over natural gas tankless water heater: Longer lifespan. The same goes for tankless vs. tank water heater.

Frequently Asked Questions (FAQ)

  • Do electric tankless heaters need venting?
    No, they don’t. Venting is only required with a tankless gas water heater.
  • 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 costs range from less than $100 USD up to $300 USD and higher.
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Questions about our electric tankless water heater reviews? Ask away!

And keep in mind 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 Maria Martino

Maria Martino is one of our part-time content creators. She owns a B.A. in Multimedia Journalism from the University of Chicago and enjoys writing about all walks of life. When she doesn’t write, Maria likes to portray people and support her local community.
Learn more about Maria and the rest of the BOS Team.

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