10 Best Electric Tankless Water Heater Reviews 2020

Do you know? 14% of energy usage in USA households comes from the water heater? And for this reason, you need to pick the right electric water heater. And we are here to help!

If you are skeptical of upgrading your old tank water system, then you need to look into the electric tankless heating systems. There are many kinds of water heater available in the market; but why tankless electric water heater?

Many reasons,

  1. They are energy efficient than conventional tank models. According to energy.gov, tankless/ on demand water heater can save up to 34% more energy than storage types. People even further optimize the electricity bills by using low-flow shower heads.
  2. They produce less noise than tank types.
  3. While people ask whether electric tankless heaters have leakage problem, We can assure they’ve least leakage problem because they don’t hold waters.
  4. The electric water heaters are affordable; half the price than gas-powered.
  5. Electric ones have cheaper installation cost than natural/ propane gas tankless.

Moreover, the electric tankless heaters last longer than the traditional ones. Well, it all adds up to why they are continuously growing in the market.

Now that you’re hopefully fired up (pun intended), without further ado, let’s take a look at the top 10 best electric tankless heater we reviewed for you.

So what’s the right electric tankless water heater you need?

Wait, Before we recommend you some products, We let you know that 2 metrics that play a vital role while selecting size.

  • Your Ground Water Temperature
  • Your Flow Rate (Gallons per minute)

At the end of this article, we have Electric Tankless Water Heater Sizing Guide. However, in each product, we’ve added a sizing chart that visualizes the size you need according to your water temperature and flow rate.

Best Electric Tankless Water Heaters

Stiebel Eltron Tempra Plus 36 kW, tankless electric water heater with Self-Modulating Power Technology & Advanced Flow Control
811 Reviews
Stiebel Eltron Tempra Plus 36 kW, tankless electric water heater with Self-Modulating Power Technology & Advanced Flow Control
  • Digital temperature control
  • Proven reliability. No venting required.
  • DRAWS 150 A. Requires minimum 300 A electric service. Dimensions (H x W x D): 14.52" x 16.54" x 4.61"

The Tempra comes with 2 models: Plus and Trend. While most of the features remains the same, the Trend tends to have higher “minimum temperature.

Also, each model has 6 variants, such as Tempra 12/15/20/24/29/36. So which option you need?

Here is a clear infographic by Tempra by which you can easily pick the right variant.

For example,

You live somewhere in Florida where your ground water temperature is ~72 deg Fahrenheit, and you do 5 GPM water usage.

Then, you need Tempra 24 (Plus/Trend).

Next, let’s discuss its specialty.

You can set the temperature ranges from 68-140 Fahrenheit. They have a digital panel where you can regulate the temperature. Also, the Stiebel Eltron Tempra Plus takes very little space so that you can place it virtually anywhere in your home.

The Tempra Advanced Flow Control is the exclusive property of Stiebel. What’s so special about it? The only thing you have to know is that with this control, you won’t be getting any cold water shocks during showers. It’s an efficient system that keeps the temperature correct.

More importantly, in addition to providing digital temperature control, its Advanced Flow Control feature automatically maintains hot water temperature. That means that your shoulder would always remain hot.

Do you know? Stiebel-Eltron has invented the first eletric tankless water heater in 1929. This model has best performance and got nice reviews from the users.
  • Non-stop hot water supply
  • Energy-efficient
  • Compact design
  • Installation can be complicated

Bosch Whole House WH27 Tronic

 Bosch Tronic

  • Dimensions: 15 x 4.5 x 12.5 inches
  • Weight: 19.65 pounds
  • Warranty:10 years

At number 2, we have the popular Bosch WH27 Tronic Whole House Electric Tankless Water Heater. The WH27 is a whole home model. They have two models: Whole house and Point-of-use. The former is for the entire house whereas the later is for the point of use places like the kitchen or bathroom sink. So, it’s obvious, and whole home models are bigger than point-of-use models.

According to Bosch, the WH27 is suitable for 1-2 bathroom home.

42°F 52°F 62°F 72°F
WH27 Tronic (GPM) 2.8 3.39 4.18 5.45


Hence, you won’t be feeling any difference in the water temperature in separate bathrooms. It can easily supply 3 outlets with hot water. Well, it’s good enough for commercial use as well. But the best place for it would be a house.

It comes with a digital display to asses the temperature. Also, there’s an external knob to control the heat as per your needs. The system is easily understandable. Furthermore, with the polymers in the body, the temperature remains constant throughout.

Its durability is undoubtedly one of the best points of the WH27. Thanks to its polymer body, don’t expect the WH27 to go anywhere before 20 years. Also, with 97% thermal efficiency, you can expect reduced bills.
  • Lightweight
  • Constant temperature throughout
  • Circuit protection needs improvement
  • Plastic / PEX materials are not suitable for the line as the water heats instant.

Ecosmart ECO – Runners Up

Ecosmart ECO 

  • Dimensions: 17 x 19 x 3.8 inches
  • Weight: 18.36 pounds
  • Warranty: Lifetime

Here at number 3, we have the EcoSmart ECO. However, it’s not just any other water heater. The cover is removable with ease. Thus, allowing you to clean it up more efficiently. Despite the small size, the inside is spacious. Hence, sparing you from the worry of overheating.

The EcoSmart comes with a flow rate of up to 6 gallons per minute in warmer climates. Thus, providing you with non-stop hot water and digital control over the range of 80 to 140 degrees Fahrenheit. This should suffice 4 showers with this rate of water flow.

Undoubtedly, the best feature of this model is its patented Self Modulating technology. It regulates the heater to adjust its temperature based on the temperature of the surroundings. That means if it is too cold out there, the heater would automatically amp up the heat to provide hot water for your needs.

Furthermore, the dimensions of 17 x 19 x 3.8 inches and weight of just 18.36 pounds make it easy to handle and set up. With the price, it is undoubtedly of great value to your money. Any DIY enthusiast with decent electrical and plumbing experience can install this.

Here’s the chart from Ecosmart. Pick the right variant according to the chart.

So what is it that makes the EcoSmart a must-have? Its enormous 6-gallons capacity. The capacity is so huge that you could simultaneously use searing hot water in multiple bathrooms.
  • Built with copper and stainless steel
  • Compact size
  • Non-stop hot water supply
  • Minimum 200 amps electrical service is required and additional breaker space in your breaker box.
  • Might corrode earlier

Sio Green IR260

Sio Green IR260 POU Infrared

  • Dimensions: 14.3 x 12.8 x 4.4 inches
  • Weight: 6.75 pounds
  • Warranty: 2-year

Here we have another water heater that doesn’t take up much space. However, the thing we commend the most about is the concern for safety, featuring a no-metal and no-coil design. Hence, you can let go the worry about the corrosion of metals. Instead, the construction of quartz and infrared technology make sure that the heater is long-lasting. If it isn’t, then the company will have your money back. That’s awesome!

Sio Green used no metals in the building of the tankless electric water heaters. Thus, making it corrosion-free. Furthermore, it does not allow bacteria and algae to grow.

Also, the small size and lightness in weight make the installation straightforward while saving you a lot of space. Since there is no risk of corrosion, that makes it a one-time investment. Thus, it will demand very little maintenance from you.

With the Sio Green, you don’t have to worry about the metals corroding. Hence, there’s very little attention that you’d have to pay for its maintenance.
  • No-metal corrosion free construction
  • No chance of calcium build up
  • Requires no maintenance
  • Not enough for a large house
  • Hot water is inconsistent

 Rheem RTEX Tankless Water Heater

Rheem RTEX

  • Dimensions: 4 x 9 x 13 inches
  • Weight: 8.5 pounds
  • Warranty: 5 years

The Rheem RTEX is another energy-efficient model we have on the list. When it comes to residential option, this one might be the best there is. Furthermore, it’s 99.8% energy-efficient.

Hence, you’d be saving a whole lot of money on the bills. One thing that you might have to consider is that the water heater is well-suited for single use only.Additionally, It’s best suited for apartments and small-med homes. Otherwise, it’s a great system.

The Rheem RTEX weighs only 8.5 pounds with the dimensions of 4 x 9 x 13 inches. Thus, making it very easy to handle and install. It’s designed to give you endless hot water on demand. Rheem RTEX comes with a digital temperature display and self-modulating power system.

It provides a 3.17-gallon max flow rate. Furthermore, the energy-efficient design is not only bill-friendly but also environment-friendly.

What makes the RTEX-13 so great to be on our list or your shopping cart? The answer lies with energy efficiency of 99.8%. I’m sure that nothing’s better than enjoying warm water with a reduced bill.
  • Easy installation
  • Energy-efficient
  • Compact and lightweight
  • Best for single use
  • Not the best for colder climates

Thermoflow Elex

Thermoflow Elex.

  • Dimensions: 13.6″ x 7.9″ x 4.8″
  • Weight: 5.4lbs
  • Warranty: 1 year

Made in Germany, the Elex model from Thermoflow mainly focuses on energy saving. While the electric tankless water heaters do less power consumption. However, the elex model can additionally save more energy. It’s possible due to they don’t need preheating, plus no standby losses.

The Thermoflow introduced Electric Temperature Control (ETC) which maintains the water temperature even if the flow rate varies.

This model comes with a digital touch screen and led display with which you can regulate the water temperature. Additionally, they don’t need any venting being powered by electricity.

  • Maintains Equal Temp
  • Energy-efficient
  • Compact
  • Customer Support can be better

iHeat Tankless S-16

iHeat Tankless

  • Maximum water output: 3.5 GPM
  • Dimensions:11.5 x 9 x 4.5 inches
  • Weight: 3.9 pounds
  • Warranty: 1 yr Elements limited, 3-Year Components, 5-yr leaks

We end our list with the iHeat Tankless Water Heater. Perhaps, this is the first outdoor option in our list with water resistance capability. The heater is enough for a sink, and two showers wherein temperature ranges between 80-140* Fahrenheit. However, in the colder regions, the application reduces to one shower for a single heater.

The iHeat Tankless is has a body of stainless steel, which makes it durable and an ideal choice for outdoor conditions, i.e. beach, a yacht, or outdoor kitchens. Its system also includes a touchpad which gives you the freedom to easily control its water and temperature.

Would you like to have hot water outside your home? If yes, then you must have the iHeat S-16. Yes! You can enjoy hot showers in your yacht too. Thanks to stainless steel, you can have warm water outside your home.
  • Lightweight and compact
  • Suitable for outdoors
  • Users reported a slight delay in hot water

Electric Mini-Tank Water Heaters

While the article focuses only on tankless water heaters, We’ve included some mini-tank alternatives.


Because sometimes people want more volume of hot water for a short period but don’t want to wait. Mini-tank heaters maintain the compactness and store a small amount of hot water. They work almost identical to tankless electric models plus storing warm water.

Bosch Tronic 3000T ES8

Bosch Tronic 3000 T

  • Dimensions: 17.5 x 17.5 x 14.5 inches
  • Weight: 29.5 pounds
  • Warranty: 6 year, 1 year parts

Are you tired of waiting for hot water? This water heater from Bosch will take care of that. In addition to supplying water to 2 sinks at a time, this point-of-use heater offers a multi-directional mounting feature. That means you can mount it on both the wall as well as the floor.

Also, to make sure that it lasts longer, the interior of the tank is designed with a glass lining. Its 7-gallon tank’s heating element provides a maximum output temperature of 145*F, and you also get a relief valve in the package.

Finally, if you already have a water heater at home, you can use the Tronic in-line with it additionally. Used that way, it would eliminate your wait for hot water.

What makes it stand out is the compactness of the unit. You can expect it to go under your sink quite easily. You can wall mount this vertically or horizontally
  • inexpensive and under $200
  • Instant hot water
  • Energy-efficient
  • Some reports of relief valve leakage
  • Calcium might build up

Ariston GL4S

Ariston GL4S

  • Dimensions: 13.8 x 13.5 x 13.8 inches
  • Weight: 23.1 pounds
  • Warranty: 6 Years Warranty, 1-year on parts

This mini-tank water heater from Ariston is bound to give you hot water without any wait. The GL4S model is the successor of Ariston GL4 with a lot of improvements from Bosch Thermotechnology. Thus, the latest model features an easy-to-use temperature control knob and a more accurate thermostat.

The Ariston GL4S is the easiest to install. That is, because, it offers plug-n-play capability. That means you can connect it directly to your kitchen sink, dishwasher, faucet or any other water hose you may like.

The Ariston GL4S mini-tank water heater comes with 4 gallons of hot water which should be enough for you. Furthermore, temperature varies from 50- 140* Fahrenheit.

You can easily set it up and use since there is no need for hard wiring. All you have to do is to connect the it to the power supply. The GL4S won’t make you wait on hot water as it has a quick recovery time.

You must’ve figured it out. The GL4S would be an upgrade if you had the GL4. Also, for a small or medium size kitchen, and sinks, this is all you need to suffice the warm water needs. Plus it’s super-easy to setup
  • Compact size
  • Quick recovery time
  • No need for hard wiring
  • 4 gallons might not be enough for some
  • Needs annual maintenance of anode

Eccotemp EM-2.5 Electric

Eccotemp EM-2.5 Electric

  • Dimensions:14.5 x 11.8 x 10.4 inches
  • Weight: 20 pounds
  • Warranty: 2 years in parts and 5 years in leaks

The Eccotemp mini water heater comes with a tank size of 2.5 gallons. Unlike most tankless heaters out there, it stores water beforehand. Moreover, the installation is pretty much straightforward.

Along with that, it gives you a temperature control of 50 to 140* Fahrenheit. Also, the Eccotemp mini has a quick recovery time of 25-45 minutes. You can also use it in series with your existing water heater, where it will act as a booster.

Equally impressive is the recovery time of this unit – which means it won’t take long to supply hot water after startup. Then comes the mounting options and you might find it pleasing to note that this unit is both floors as well as wall mountable.

Whether you connect it to the cold water directly, or with a larger heater, the Eccotemp is going to make an impact.
  • You can install it anywhere
  • Quick recovery time
  • No need for re-circulating pumps
  • Limited water supply
  • Water inside could be challenging to drain

Electric Tankless Water Heater Sizing Guide:

The water heater used in New York shouldn’t be used in Florida. Moreover, it depends upon your water usage too. For example, a clothes washer will use more water than a bathroom faucet. Choose what suits best to your usage and location.

Interesting? You want to know why?

We’ll Describe you this in 3 simple steps, No big deal, just 3 steps.

Step 1: Calculate how much hot water flow you need. 

This should be calculated as GPM = Gallon Per Minutes. Below, we’ve given some rough data about water flow rates according to appliance type.

Fixture / Appliances – Typical Flow Rates

  • Bathroom Faucet: 0.5 – 1.5 GPM
  • Low Flow Kitchen Faucet: 1.0 – 2.5 GPM
  • Shower: 1.0 – 2.0 GPM
  • Dishwasher: 1.0 – 2.5 GPM
  • Washing Machine:1.5 – 3.0 GPM

So, if your house has 2 Bathroom Faucet and 1 Shower (both running at the same time), Your required flow rate will be a maximum of 5 GPM. Which equals to, per minute you are consuming 5 gallons of water.

Step 2: Note where you live from 4 different United States regions. 

Step 3: Now, calculate and select the right variant which can satisfy your needs. 

Now, let’s say you live in Florida, and you want 5 GPM water flow. Then, you need a tankless water heater which can provide 5 GPM flow @ 70 deg F / 35 deg rise @ 5 GPM.

  • The max water temperature you want = 105 deg F. 

Things to Look in an Electric Tankless Water Heater

Determine the flow rate you need

In contrast to your average tank type, tankless water heaters don’t provide unlimited flow-rate. Instead, they have a specific output called flow-rate. Provided your demand exceeds the flow-rate, you won’t be getting any hot water.

To determine the flow rate that you might need, here’s what the important thing you should do:

  • Identify the no of water devices (faucet, shower, sink) you’re going to need hot water for
  • Calculate the combined flow rate of all these devices
  • Your ideal tankless water heater should exceed this flow-rate by at least 1GPM

Check out the Heater’s Energy Efficiency

They should require less Watts of electricity to heat water.

Also, in addition to checking out your heater’s efficiency, there one more thing you need to know: increase in your hot water requirement will decrease the efficiency and savings. Therefore, if your hot water requirements are huge, make sure your heater’s efficiency is at least 90%.

Know About the Warranty

In contrast to what most people believe, heaters do not provide a one-size-meets-all warranty. Instead, most heaters in this review provide at least three types of warranties.

The first of those warranties is the one offered on the heat exchanger, which generally lies between 5 to 15 years. Next comes the warranty on parts, which is valid for 2 to 5 years. Finally, you’d have the labor warranty. It is the lowest of the three and usually comprises of only 1 year.


With the growing popularity of tankless heaters, you should get one too. Hopefully, by now you would’ve made your mind. The first things that you should address are your needs and your budget. Tankless water heaters might cost more, but they save money on bills. So getting one is not a bad deal after all.

Out of a lot of best electric tankless water heaters, my pick would have to be the winner of this list the Stiebel Eltron Tempra Plus.

That’s all folks.

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