10 of the Best Electric Water Heaters on Earth Defined (2020 Buyers Guide)

Are you tired of rampant power bills from heating hot water needlessly?

If so, we’re sure you don’t want to sacrifice hot water when you need it to realize savings on your power bills.

With the best electric tankless water heater, you don’t need to compromise.

Since looking for the most effective model can be remarkably time-consuming, we’ve rounded up a top 10 so you can compare these heaters at a glance and see which one makes the best fit.

We’ll dive straight into the reviews right now…

1) Atmor AT-910-24TP

This lean, understated electric tankless water heater serves up on-demand hot water instantaneously thanks to the self-modulating tech in place.

The user-friendly digital panel shows you the temperature which you can tweak by single degrees. The interface is simple and user-friendly.

The 4.6 GPM capacity works well in small or mid-sized homes where you’ll be running up to 4 applications at once.

As an example, you could use the shower along with the faucet in the kitchen and bathroom at incoming temperatures of 73 Fahrenheit degrees. If the inlet temperature is cooler, both flow rate and number of applications will dip.

This tankless heater has a tiny footprint so you can pop it practically anywhere. You won’t need any venting and it comes IP54-certified so all internal components will stay safe and dry.

For hot water on tap without standing on ceremony and the ability to save money on your energy bills, this Atmor punches above its slimline weight.


  • Intuitive digital temperature control
  • Rugged stainless steel interior build
  • Rock-solid 7-year anti-leak warranty


  • Wiring diagram is wrong which is inexcusable

2) Chronomite SR-20L/240 HTR

If you’re looking for an instant-flow hardwired tankless heater to slot under the sink, this space-saver from Chronomite is tailor-made.

While this set-up limits you to a single application, in return you’ll get almost instant hot water without waiting the 6 or 7 seconds common with tankless heaters. There’s no risk of scalding, either with the Chronomite ADA-certified to prove this.

The SR series are 99% energy-efficient. With 240 volts and consumption of 4800 watts, you won’t lose out on power to achieve those energy savings.

Self-cleaning to eliminate calcification and alkali build-up, maintenance is reduced to practically nil.

This heater works effectively in colder climates and will still deliver streams of piping hot water any time you need it.


  • Hot water delivered with almost no lag
  • Point-of-use on-demand unit for maximum energy-efficiency
  • Compact and smaller than a laptop


  • Modest 0.5 GPM flow rate
  • Limited to a single application

3) EcoSmart ECO 11

The baby of the EcoSmart stable, the ECO 11 serves up on-demand water with the capacity to save up to 50% on your power bills at a very keen price-point.

This is a smaller unit so while you can slip it almost anywhere, this size brings about a drawback…

If you’re over-extending the heater, you might find the temperature becomes slightly unstable so think closely about intended use.

As long as the ambient temperature is 67 Fahrenheit degrees and above, you’ll be able to use a couple applications simultaneously with a total flow rate of 2 GPM. This is a surprise bonus given the form factor.

In cooler climates, the ECO 11 works well as a point of use unit or for low-flow applications.

Remarkably efficient with an EF rating of 0.98, you can expect to realize dramatic savings on your water heating expenses with the ECO 11.


  • 98% energy-efficient so save money while reducing your eco-footprint
  • Use for multiple applications (climate-dependent)
  • Exceptional price/performance ratio


  • Temperature can fluctuate under heavy use

4) EcoSmart ECO 27

The ECO 27 is the largest tankless heater packing self-modulating technology.

When the weather is cold with incoming water as cool as 37 Fahrenheit degrees, this heater can still warm up almost 3 Gallons Per Minute.

In hotter climates, you’ll get up to 6 GPM. This tankless heater is designed to serve demanding applications like hot tubs and Jacuzzis and is a hard-hitter across the board.

Despite this performance, energy-efficiency is 99.8% although this unit is not ENERGY STAR-certified.

Working well for a single-family home with fairly heavy water demands, the precise control afforded by the digital interface and diminutive form despite that performance brings about a winning combination from EcoSmart.


  • Space-saving design while robust enough for multiple applications
  • Impressive flow rate maxing out at 6 GPM
  • Wide temperature range from 80 to 140 Fahrenheit degrees


  • Maintenance can be costly so factor this in
  • Customer service is fairly limp

5) Eemax EEM24018

This small but powerful tankless heater calls for a few things in place to work effectively. Make sure you have a pair of 40-amp breakers in place then you’re good to go.

While marketed at residential and commercial applications, this is really very much a model for home use.

In warmer weather, you can use up to 4 showers at the same time. If the mercury is lower, you’ll still be able to use a shower while operating a couple sink faucets so performance is robust.

Flow rate is modest at 2 GPM but you’ll still enjoy hot water on demand while potentially saving money on your utility bills. Self-modulating tech fine-tunes input in line with demand.

For a space-saving tankless water heater ideal for smaller properties, the Eemax is well worth popping on your shortlist.


  • Self-modulating unit adjusts energy on an input-based and automated model
  • Measures just 17 x 14 x 3.8 inches so perfect for cramped spaces
  • Ideal for cool or warm climates


  • Draws down fair amount of power

6) iHeat S-16

The iHeat S-16 is a waterproof unit coming in stainless steel at a reasonably keen price.

Use a pair of showers at 1.5 GMP apiece in warmer areas while in colder climates you can use the S-16 as a point of use heater with a reduced volume of water heated up.

Despite the marketing concerning hospitals and sterile environments, consider the S-16 a solid unit for smaller homes.

As a tip, if you require increased temperature, consider switching your faucets to low-flow fixtures to achieve this.

While limited in scope, you’ll get a compact and capable tankless heater in the S-16 perfect for single families in apartments or small houses from a brand you can trust.


  • Rugged stainless steel build
  • Fully waterproof construction
  • Works as point of use heater in cold climates


  • Some issues reported with lifespan

7) Rheem RTEX-13

Rheem is a stellar presence in the water heater vertical and the RTEX-13 is a high-efficiency unit with durable build and impressive performance.

Working well as a point of use application or for multiple applications simultaneously, the RTEX-13 is small enough to install anywhere and a breeze to set up. With all you need thrown in, you can get going straight out the box.

Crisp controls allow you to fine-tune the temperature in 1-degree increments and flow rate is 1.5 GPM.

As long as you have a 60-amp breaker box in place and you live somewhere with warmer weather, this is a capable and affordable unit from a highly reputable brand.


  • Dual heating elements and 99.8% energy-efficient
  • Everything needed for installation is bundled
  • Lightweight and compact


  • You’ll need a 60-amp breaker box
  • Doesn’t work so well in colder climates

8) Stiebel Eltron Tempra 20 Plus

You can expect at least 10 to 15 years of faithful service from this potent tankless water heater.

Flow rate is up to 3.75 GPM at 35 Fahrenheit degrees while advanced thermostatic controls ensure your hot water is optimized around the clock.

You can enjoy constant hot water even under heavy demand thanks to the flow technology onboard. Temperature shouldn’t fluctuate, a common bugbear with cheaper models.

With straightforward installation and no need for venting, the Tempra 20 Plus is not cheap but represents sterling overall value.


  • You won’t need to worry about venting
  • Runs whisper-quiet
  • Solid copper heating chambers for enhanced performance


  • Warranty voided if you sidestep professional installation

9) Stiebel Eltron Tempra 24 Plus

In business for almost a century, Stiebel Eltron dominate the tankless water heater space. The Tempra 24 Plus is arguably the best model in a broad and deep range.

With a maximum temperature limit of 109 Fahrenheit degrees in place, you’ll run no risk of scalding. On-demand water supply is abundant and delivery is unerringly accurate.

Maximum flow rate is a class-leading 5.5 GPM so you’ll be able to service 2 bathrooms without a hitch.

Despite such wide-reaching technology baked in, the 24 is a breeze to use even if you normally struggle with this type of appliance.

As long as you have the power to accommodate this tankless heater, you won’t regret your decision to invest. Significant energy savings ice the cake.


  • Outstanding 99% energy-efficiency
  • Endless hot water with no interruptions to temperature
  • Consistency of supply is complemented by precision


  • Installation is awkward
  • Requires a lot of power to get going

10) Stiebel Eltron Tempra 15 Plus

The baby of the Tempra Plus range, you’ll nevertheless be able to provide hot water on demand throughout the whole house with the 15.

As long as the incoming water temperature is 65 Fahrenheit degrees or more, you’ll enjoy flow rates of up to 3.3 GPM. If pressed into service in cooler climates, expect flow rate to drop to 1.5 GPM.

You’ll get the true thermostatic temperature control and complete power modulation Stiebel Eltron are famous for without needing a hulking unit eating up too much precious real estate.

As with all tankless heaters from this brand, you’ll be paying a premium but you’ll be rewarded with a long-lasting, efficient and highly capable unit packed with bells and whistles.


  • Smallest Plus heater cut out for whole-house use
  • Energy-efficiency of 99%
  • Usual dependable Stiebel Eltron warranty


  • Works better when incoming water temperature is at least 65 Fahrenheit degrees
  • Doesn’t respond well with harder water


Still unsure which heater would make the neatest fit in your home?

If forced to choose just a single unit, our overall pick is the Stiebel Eltron Tempra 24 Plus. Although not cheap, the best things in life seldom are. You’ll get exceptional energy-efficiency, excellent lifespan and superb performance in every area all from a brand you can reply on. What’s not to love?

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