The 5 Best Electric Tankless Water Heaters of 2021

Best Electric Tankless Water Heaters
Image by Canva Photos

If you’re reading this article, you likely already know that electric tankless water heaters are pretty great. They take up dramatically less space than traditional tank heaters, they’re ultra-efficient, eco-friendly, and can save you some serious money over time. Plus, who doesn’t want access to an endlessly hot shower, on-demand? So out of all the options, what is the best electric tankless water heater? 

To answer that question, we’ve combed through lots of the best whole house electric tankless water heater reviews and summaries. Read on for our top picks, and learn how to choose the tankless water heater that’s right for you. 

Our Top Picks

EcoSmart ECO 27 Electric Tankless Water Heater Best Overall: EcoSmart ECO 27 Electric Tankless Water Heater
The ECO 27’s patented self-modulating technology means quickly and efficiently meeting hot water demand, even in cold climates.
Ecosmart ECO 18 Electric Tankless Water Heater Best Budget: Ecosmart ECO 18 Electric Tankless Water Heater
For slightly less extensive hot water needs, the more affordable ECO 18 is also an efficient and dependable choice.
Rheem RETEX-27 Performance Self-Modulating Tankless Electric Water Heater Best Eco-Friendly: Rheem RETEX-27 Performance Self-Modulating Water Heater
Ultra-efficient and built to last, the RETEX-27 has replaceable heating elements and a good track record.
Stiebel Tempra 36 Plus Compact Residential Electric Tankless Water Heater Best for Large Households: Stiebel Tempra 36 Plus Compact Residential Water Heater
The Stiebel Tempra 36 Plus electric tankless water heater is extremely well-reviewed and offers powerful performance in larger households and colder climates.
ECOTOUCH on Demand Instant Hot Water Heater Best Point of Use: ECOTOUCH on Demand Instant Hot Water Heater
The ECOTOUCH on-demand tankless water heater is an affordable, compact point of use option.
 

A Closer Look: Best Tankless Electric Water Heaters

Now that we’re all warmed up, let’s take a closer look at eat of our top picks.

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1. EcoSmart ECO 27 Electric Tankless Water Heater

The best electric tankless water heater overall

Brand: EcoSmart | Wattage: 27 kW | Volts: 240 | Amperage Draw: 112.5 | Flow Rate: 6.5 GPM | Price: 💰💰💰

The ECO 27 is one of the best rated electric tankless water heaters, and is available at a lot of retailers, so you can keep an eye out for sales. It also comes in a variety of “sizes” for different kilowatt and voltage levels, so you can purchase the one that’s just right for your climate, usage, and electrical setup. 

The ECO 27 is in the upper mid-range of those options and is our choice for the best whole house electric tankless water heater. It provides enough on-demand hot water for some of the most common scenarios, such as: running two showers simultaneously or being able to shower at the same time someone is running the dishwasher elsewhere.

EcoSmart is one of the most trusted tankless water heater brands. Their extremely efficient electric heaters have patented self-modulating technology, which helps them continually meet hot water demand, even in colder climates. 

  • Lifetime warranty
  • “Loads of hot water”
  • Fast, powerful, convenient
  • Good customer service/replacement parts
  • Multiple people can take showers back-to-back or run appliances simultaneously
  • Max temp too low
  • May need to up the electrical voltage in your home
  • Flow rate and other specifications may be exaggerated
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2. Ecosmart ECO 18 Electric Tankless Water Heater

The best budget electric tankless water heater

Brand: EcoSmart | Wattage: 18 kW | Volts: 240 | Amperage Draw: 75 | Flow Rate: 2.73 GPM | Price: 💰💰

Two in a row for EcoSmart! The EcoSmart ECO 18 is an excellent middle-of-the-road tankless water heater, at a slightly more affordable price than our overall pick. The unit itself is very compact, energy-saving, and easier to install than many heaters. (Professional installation is still recommended.) 

This economical water heater is perfect for apartments, townhomes, condominiums, and other similarly sized homes. It provides a flow rate of up to 2.73 gallons per minute, which is about what you need for a long, hot shower. If you live in a warmer climate, you may be able to get away with running a second shower or another sink at the same time.

The ECO 18 might struggle in colder climates, however. If you live someplace with cold incoming water temperatures or in a home with lots of people, we recommend upping your budget and going with one of the other water heaters on our list. 

  • Quiet
  • Easy to read display
  • “Performs flawlessly”
  • Easier to install than some
  • Easy to adjust the temperature
  • Some had issues with corrosion or leaks
  • Not always ideal for running multiple showers at once
  • Make sure to register the product within 30 days, or the warranty is voided
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3. Rheem RETEX-27 Performance Water Heater

The best eco-friendly electric tankless water heater

Brand: Rheem | Wattage: 27 kW | Volts: 240 | Amperage Draw: 112.5 | Flow Rate: 5.3 GPM | Price: 💰💰💰

All our picks for electric tankless water heaters are inherently earth-friendly choices because they’re all so much more efficient than traditional tank heaters. But the very energy efficient Rheem RETEX-27 is our choice for the best eco-friendly tankless heater. It lasts a long time and has self-regulating technology that makes it up to 99.9% energy efficient. It’s easy to maintain and features durable parts with easy-to-replace heating elements.

Like other tankless water heaters, the RETEX-27 will only kick on when you turn on the hot water. This dramatically cuts down on loss of heat and can save you up to 60% in overall heating costs. It also has an adjustable digital temperature control, so you can dial in on your perfect temperature within 1-degree increments.

  • Consistent temperature
  • Thorough instruction manual
  • Noticeable savings on utility bills
  • Larger size is worth the extra money
  • “Been using Rheem brand water heaters for years”
  • Not a DIY installation
  • “Power draw was significantly more than advertised”
  • Some had trouble with lights flickering during heater use

4. Stiebel Tempra 36 Plus Compact Residential Water Heater

The best large household electric tankless water heater

Brand: Stiebel Eltron | Wattage: 36 kW | Volts: 240 | Amperage Draw: 150 | Flow Rate: 7 GPM | Price: 💰💰💰💰

Some of us require more hot water, in more locations, more often. If you have a large family or live in a house where multiple people (or appliances) require hot water at the same time, you’ll need an electric water heater with a more powerful output. Our favorite option is the Stiebel Tempra 36 Plus. 

What makes this Stiebel water heater different?

“Tempra Plus models feature Advanced Flow Control, patented in Germany and exclusive to Stiebel Eltron tankless heaters. If hot water demand exceeds working capacity, Advanced Flow Control automatically maintains consistent temperatures by slightly reducing flow.” 

Which basically means you can run 2-4 bathrooms at a time with consistently hot water, depending on your climate. 

The most important thing with a higher-voltage electric water heater is to make sure that your home has enough amperage to be able to handle it. In the case of this Stiebel model, your home needs to have 300A of “minimum recommended household electric service” in order to run this tankless water heater.

  • Good investment
  • “Works flawlessly”
  • Heat adjustment knob
  • Straightforward installation
  • High required amperage
  • Reduction of hot water flow in winter months

5. ECOTOUCH on Demand Instant Hot Water Heater

The best point of use electric tankless water heater

Brand: ECOTOUCH | Wattage: 9 kW | Volts: 240 | Amperage Draw: 37.5 | Flow Rate: 1.5 GPM | Price: 💰

Sometimes you need an on-demand electric water heater for a smaller or single application, such as a sink, washing machine, or dishwasher. If that’s the case, the ECOTOUCH 9kW instant water heater is a handy and relatively affordable option. 

This compact point of use heater uses energy sparingly, clocking in at 99.8% efficient; the unit even self-adjusts based on the incoming temperature and flow rate to use as little energy as possible.

The ECOTOUCH features a sleek modern design that barely takes up much space at all, measuring 15.4″(H) x 10.3″(W) x 2″(D). Users also appreciate its touch control panel and easy-to-read digital display. 

  • Small and unobtrusive
  • Great for supplementary use in larger houses
  • If you live in a warm climate, you can get away with using it to heat a shower
  • Perfect for mobile homes, cottages, small apartments, kitchen sinks, bathroom sinks
  • Inconsistent customer service
  • Doesn’t include bottom mounting bracket

Why Electric? 

Fully installed electric water heates
Image by Canva Photos

Besides its higher upfront cost, a tankless water heater is going to beat a traditional tank heater in nearly every category.

But if you’re trying to decide between gas vs. electric tankless water heaters, here are a few arguments in favor of going electric: 

  • Electric tankless water heaters are safer and easier to maintain. While electric water heaters require maintenance and regular flushing, they don’t need the frequent careful inspections required of gas heaters. There also isn’t any potential for gas leaks with an electric heater.
  • Electric tankless water heaters are cheaper upfront. As we’ve seen on our list, electric heaters are certainly not cheap, but tankless gas water heaters can cost twice as much as electric ones. The overall cost to run a water heater will hugely depend on the climate and utility costs where you live. Still, electric water heaters make a little less of a dent in the pocketbook initially.
  • Electric tankless water heaters are easier to install. -but still require a professional! Most everyone has electrical hookups in their house, but not everyone has natural gas. Electric tankless heaters are generally smaller and less complicated than gas heaters, and they don’t require any special venting.

How to Choose the Best Tankless Electric Water Heaters 

Overall, “sizing” an electric water heater can be a complicated and challenging task because it’s so dependent on the environment, the number of people, and the electricity use of a particular household. We recommend doing your homework no matter which type you buy — many tankless water heater manufacturers offer customized help in determining exactly which water heater is right for you. There are also lots of online buying guides, charts, and calculators to assist you in your choice. 

That said, here are a few general things to consider when selecting your tankless water heater:

1

Electrical Input

The amount of energy needed to heat water to a given temperature is measured in “British thermal units,” or BTUs. The temperature of the incoming water will affect how many BTUs your heater will have to expend in order to heat the water, as will the number of showers or appliances in use. This is where determining the necessary power for your electric tankless water heater gets a little complicated and likely requires some math. 

The basic idea is that you want both your home and your tankless water heater to have enough electrical “oomph” to be able to heat incoming water (whatever its temperature) quickly and efficiently enough for your usage. Whether you’re using a point of use water heater for a small sink in Florida, or you need enough BTUs to be able to power 2 showers and a washing machine simultaneously in the winter in Minnesota — you’ll need to do your homework to determine your electrical input and amperage needs. 

2

Flow Rate

Gallons per minute, or GPM, is the volume of water your heater is capable of heating in a minute. A typical shower requires around 2 GPM, whereas a sink is more like 0.5 or 1 GPM. If you wanted to run those simultaneously, you’d need to make sure your tankless water heater has a rating of 3 or more GPM. Larger whole-house use may require more like 5 or 6 GPM.

3

Installation

Some tankless water heater users claim “easy installation,” but unless you have the skills of both a plumber and an electrician, we (and nearly every manufacturer) recommend getting professional help to install your tankless electric water heater. This will add a little upfront cost, but in the long run, you’ll be glad you correctly installed the right water heater for your particular setup.

Our Process

For this guide on the best electric tankless water heaters, our team spent 7 hours researching the most popular options from over 30 brands and manufacturers big and small. We then read about one hundred user reviews (both positive and negative) to discover what shoppers thought about each electric tankless water heater. After comparing this data, we narrowed our list down to the top 5 electric tankless water heaters on the market. You can count on this research to guide you to a mindful purchasing decision.

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Further Reading

Adjusting the temperature on a Gas or Electric Tankless Water Heater
Gas vs. Electric Tankless Water Heaters
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The Best Space Heater for Large Rooms
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Best Solar Generators
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The 10 Best Portable Generators for Home Use