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10 Best Electronic Tankless Water Heaters 2021

With the rapid development of technology tankless water heaters have slowly begun replacing the tank water heaters, which are expensive, power-Consuming, and require a tremendous amount of space in bathrooms, kitchens or basements. The tankless water heater market has shown massive growth over the past few years.

In this article, we’ve highlighted the features worth looking into, as well as the 10 best electronic tankless water heaters worth checking out.


Research on choosing the best electric tankless water heaters


Aside from the aforementioned criteria to focus on, more research may be necessary to provide more reliable and Consistent information. One of the most important things to consider are

  • Warranty
  • Company’s reputation

Warranty is important because it tells a lot about the product’s reliability and durability. Most electric tankless water heaters have a good warranty from anywhere from five to seven years, while some more premium models can last up to ten years under warranty. Some manufacturers also provide separate, slightly shorter warranty for certain parts which are prone to wearing out earlier.

Good tankless systems can last up to 20 years, while propane and natural gas tankless water heaters can last up to 30 years, and as such, they have longer warranties. They are also more environmentally friendly, spend less electrical energy other than for displays or safety systems.

Another important thing to search on is the company’s reputation, meaning how well do they do the installation, in case you can’t do it on your own, the expenses of technical service, the amount of time they take to repair if it comes down to malfunction and lastly, the customer service, how active and attentive it is, and how much knowledgeable they are to help.

Another thing you need to research is the electrical requirements for your households. Because they don’t have vents, they can be installed pretty much anywhere, although the installation expenses may be much higher if the upgrade is necessary for the system to work in your household. They are also smaller than the gas-based water heaters so they can be installed in any location where the gas heater can’t be installed, even under the sink. Also, being there are no exhaustion gases, there won’t be a requirement for a venting system.

If you want to install the electric tankless water heater on your own, you should have at least some electric-related and handyman knowledge and experience to avoid hazards. There are plenty of forums and YouTube channels that provide necessary tutorials about the installation process.

Things to look into when purchasing tankless water heaters


Shopping for electronic tankless water heaters can be extremely challenging and mind-boggling because there are a lot of features to Consider. Further down, we’ve listed what to focus on when springing for an electronic water heater.

1. Household

Even though tankless water heaters can provide endless hot water support within a tap, it’s important to understand that the size of household, number of bathrooms, kitchens, and sinks greatly affects efficiency. Not all tankless water heaters can provide support for whole household or simultaneous support for different areas. If you own more than three bathrooms, you might want to install more than one heater to keep up with the water demand.

2. Energy-efficiency

Logically, because they are powered by electricity, electric tankless water heaters require more power. Fortunately, companies like Ecosmart, Rheem and Stiebel Eltron provide fewer power-Consumptions for more performance. Anything that reaches over 98% of energy efficiency is worth checking out. Although they require less power than tanked water heaters, they can still be the drivers of high electricity bills.

3. Size

Size is an important factor. You need to be able to position your water heater in an area in the bathroom or somewhere in the house that it’s accessible to all other rooms that are in demand for hot water. That’s why it’s important to look for compact options if you live in an apartment and are limited in space.

4. Temperature

Temperature is an important factor if you live in the Northern or Southern parts of the USA. The north is usually colder, so it’s important to establish reliable water pressure and GPM. While most of the listed electric tankless water heaters are efficient in both areas, it’s important to check the GPM and temperature range they correspond with. Also, some heaters will only begin heating water when the heater is set at a certain GPM, and that pressure depends on the temperatures outside.

10 best electric tankless water heaters


To make making choice easier for you, we classified three of the best electric tankless water heaters. That said, we’ve chosen the

  1. The best electric tankless water heater overall – Ecosmart ECO 36
  2. The best budget electric tankless water heater – Bosch Tronic 3000
  3. The best compact electric tankless water heater – Titan SCR2 N-120

1. Ecosmart ECO 36- The best electric tankless water heater overall


  • Price: $$
  • Weight: 18.35 pounds
  • Dimensions: 17 x 19 x 3.8 inches
  • Warranty: Limited Lifetime Warranty

When it comes to the most energy-efficient and eco-friendly manufacturers, Ecosmart is at the top because it delivers both value and high-end performance. Ecosmart ECO 36 is no exception. Hence we listed it as the first best electric tankless water heater in our list. It is perfect for small to medium apartments and houses thanks to its compact and space-friendly design. However, it can also be used in the small to medium offices, if you want fast and reliable water heating. The company excels at delivering similar products so you’ll find different products other than tankless water heaters, like pool heaters, spa heaters, radiant heating systems, and other accessories that help the said products work faster.

The reason why Ecosmart ECO 36 excels is that it is suitable for both hotter and colder areas. The northern temperatures in the USA oftentimes drop extremely low, 28-37F, with ECO 36 being capable of delivering 3.5 GPM (Gallons-per Minute,) which is enough for up to two simultaneous, long showers without having to heat the water again. On the other hand, Ecosmart ECO 36 is perfect for the hotter areas too because on high, summer temperatures it can deliver up to 6.5 GPM, which can handle nearly twice as much compared to winter. Ecosmart has efficiency in mind, so even if your demands for hot water are higher, it’ll still deliver the value you’re looking for.

It is also equipped with a stunning and smart design that easily displays the current temperature. The remote has intuitive iCons, so it won’t be too long until you get used to its functionalities. Given its compact size, you don’t have to worry about not being able to fit it in the bathroom, as its pipe fitting is ¾-inch NPT. Another good thing is that its remote sports 1-degree increment so you can quickly adjust the water heating to the temperature you like.

Although everything we reviewed on ECO 36 seems nearly perfect, there are some drawbacks worth mentioning. Ecosmart ECO 36 won’t turn on and start heating the water until the flow rate is higher than 0.25 GPM, which can prolong the times of heating water. Even though it begins heating water immediately after turning it on, this rate will slow the flow and delay delivery to the faucet as the water gets flushed out through the pipes.


Compact design, suitable for both southern and northern areas, smart controls, 99% energy-efficient.


It has delayed water heating due to the 0.25 GPM threshold.

2. Titan SCR2 N-120 – The best compact electric tankless water heater


  • Price: $
  • Weight: 2 pounds
  • Dimensions: 12 x 10 x 5 inches
  • Warranty: 10 years

Although ECO 36 is extremely compact and suitable for small homes and offices, you’d be surprised how more compact and practical can the best electric tankless water heaters be. It is equipped with various abilities which make up to its great performance.

The energy rating of this product is 99.5%, which means it’s also one of the most energy-efficient heaters and will help you save more money in the future.

Because of its lightweight dimensions and smart design, it’s extremely versatile and easy to install. You can use it in both small offices and homes, as well as larger homes with up to three bathrooms.

Similarly to ECO 36, it is suitable for both southern and northern areas, with capability to offer maximum flow rate of 4.0 GPM at 20F which is more than enough for two simultaneous, long showers. It is equipped with an easy to use push to use button, which controls the temperature with a graph that helps you manage it easier. Although it’s suitable for cold homes, its capabilities excel at warmer climate where it can provide inlet water temperature of 65 degrees F. Also it has a long-lasting warranty on all components that are responsible for the water components. Another great thing about it is that it’s much cheaper compared to some other, larger heaters and can yet deliver as much performance if not more.


Compact, easy to install, long warranty, affordable


High inlet water temperature

3. Bosch Tronic 3000 – The best budget electric tankless water heater


  • Price: $
  • Weight: 5 pounds
  • Dimensions: 12.2 x 3 x 6.5 inches
  • Warranty: 5 years.

When it comes to the best budget-friendly options, Bosch Tronic 3000 excels at its heating capabilities, and it’s one of the best point-of-use water heaters you can find. Bosch ships three different options of it, starting at 3.4kW, 7.2 kW and 12 kW. It has energy efficiency of 98%, and it doesn’t Consume electricity in standby, meaning it’ll heat your water only on demand.

Unfortunately, none but the 12 kW options cannot be used on showers, but rather have applications in the kitchen and bathroom sinks because they can’t heat enough water for the shower. Nevertheless, the 12 kW option boasts a steady flow rate of 1.8 GPM at a temperature rise of 45F, while the 1.1 GPM flow rate is designed for the higher temperatures of 75 degrees F. All models are often found in both residential and commercial applications, best suitable for small homes, apartments and offices. Its smart and versatile design allows Consumers to mount it on the wall or beneath the sink both horizontally and vertically.


Extremely compact, affordable, easy to mount, comes with different models at similar prices.


Only the 12 kW option can be used for showers, mostly in hot areas.

4. Atmor AT-D18TP-AZ


  • Price: $
  • Weight: 17 pounds
  • Dimensions: 17.4 x 5.2 x 13.4 inches
  • Warranty: 7 years

Although Atmor AT-D18TP is the new player on the best electric tankless water heaters, it doesn’t mean it doesn’t deliver impressive performance and a great value. The first thing about it that flatters is that it’s compact and has a stylish matte design you’ll easily fall in love with. It has already prevailed in the tankless heater industry because it wants to deliver comfort and safety over other factors hence it’s equipped with an IP54 certification, which makes it safe against the splashes and rests you assured you can install it in the bathroom. That doesn’t mean, however, that you should point the entire shower in its direction.

Another great thing about it is that it allows you to install it close to the showers and sinks and deliver on-demand water heating experience, meaning it won’t Consume electricity when in standby, making it ideal for efficiency awareness and eco-friendly homes. The manufacturer promises up to 50% energy savings with it, which means this design wins over the tank water heaters that demand more. There’s also a small digital panel that accurately shows the temperature with a maximum of 3.7 GPM flow, which is good enough for one shower and one faucet. That said, this model isn’t good for simultaneous showers and will need another heating once the shower is spent.


Ideal for cold climates, a lot of quality features, easy to use and install


Bad for simultaneous showers.

5. Ecosmart ECO 27


  • Price: $$
  • Weight: 11 pounds
  • Dimensions:
    3.6 x 17 x 17 inches
  • Warranty: Lifetime warranty with professional installation.

The ECO 27 is slightly more affordable option compared to ECO 36, but the features to price ratio are still good enough to support houses with multiple bathrooms or small offices. Additionally, there’s a professional installation option that comes with a lifetime warranty. Both ECO 27 and 36 come with a compact design and sport the same technologies. It’s also worth noting that ECO 27 is easy to install, maintain, and if needed replace.

It’s worth noting that because it’s less sophisticated compared to the 36 version, it can provide less GPM support. That said, there are three separated 9KW operators. It’s a great option for those who are limited on budget and don’t have as many bathrooms to maintain. Also, it’s equipped with copper and stainless steel that enable it to be more durable and efficient. It is stylish-looking and great to install wherever you want.

While the ECO 36 could handle up to three showers going on simultaneously, the ECO 27 is suitable for up to two showers that are going on at the same time, although given its compact design and price, that’s normal, so it’s great for getting in houses with up to two to three bathrooms.


Compact design, intuitive display, supports simultaneous shower, suitable for both cold and hot areas.


Up to two simultaneous showers.

6. Bosch WH27

  • Price: $$
  • Weight: 19.65 pounds
  • Dimensions: 15.5 x 4.5 x 12.5 inches
  • Warranty: 10 years

Bosch is a notable electronics manufacturer in Europe, and it delivers only top qualities within the budget. Similarly to the model we highlighted above, it’s great for compact homes and offices that are looking for a powerful water heating components. It’s great for both showers and sinks, and capable of running two major applications without running out of hot water. Additionally, it’s equipped with electronic flow sensor and modulating unit that allows getting rid of the different temperature fluctuations so that the temperature output would be Constant and reliable. It also supports the maximum 3.3 GPM storage for 55F temperature rise, making it ideal for moderate to warmer areas. Although it is equipped with various energy-efficient features, Bosch WH27 Chronic isn’t the best energy-efficient option available on the market, and it’s marked with 97% energy efficiency. Nevertheless, its GPM storage allows enhanced scale residences as long as there are no more than two bathrooms in it.


Good for moderate and warmer areas, smart features for simultaneous running, easy to install, long warranty


Not the most energy-efficient unit.

7. Rheem RTEX 18


  • Price: $$
  • Weight: 8.5 pounds
  • Dimensions: 4 x 15 x 19 inches
  • Warranty: 5 years

Rheem RTEX 18 is one of the better electric tankless water heaters on the market because it can provide superb support in the colder areas for both residential and commercial purposes. It can provide on-demand and hot water supply for multiple applications or single point-of-use, which depends on how you’ll install it in your home. Its efficiency level is ranked at 99.8% meaning it’s extremely eco-friendly.

What makes it better than the competition is its external thermostatic digital control and LED display that make it easily accessible even to people who are not very tech-savvy, and change temperatures at one-degree increment.

It’s great for both colder and warmer environments, with support of 80-140F degrees for the colder areas as well as the maximum flow rate at 4.4 GPM. That said, users can squeeze up to two showers or one shower and a faucet. It’s also equipped with a self-modulation technology that intelligently adjusts and detects the desired power needed for reaching the needed temperature as soon as possible, which is its most demanded eco-friendly features.

Also, it’s easy to install and maintain, as well as replace or move to the other area. In addition to that, it is equipped with copper-immersed heating elements, which make it more durable in the colder areas.


Easy to install, automatic power-adjusting features, ideal for both cold and warm areas.


Can’t always produce two shower performance, no simultaneous performance.

8. Stiebel Eltron 230628


  • Price: $
  • Weight: 5.95
  • Dimensions:
    4.1 x 7.9 x 14.2 inches
  • Warranty: 3 years

Stiebel Eltron DHC E-12 is great when it comes to supporting both warmer and colder climates, delivering impeccable performance in both areas. It is also extremely energy efficient thanks to its 99% efficiency rating and allows for 20% energy savings over-time. Although this rating is lower compared to some other tankless water heaters listed in this buying guide, it still delivers great price to value ratio. It is great for both residential and commercial applications, which makes it suitable for homes as well as offices.

It is equipped with a sleek temperature knob, which allows you adjust between 86F to 125F. It is also great because it warms fast and efficiently. It is, however, equipped with a 1.5 GPM flow rate, which makes it enough for only one shower. Its sleek and modern design also makes it look extremely attractive and suitable for any place. It is also easy and fast to assemble. In addition to the shower amount flaw, this product comes with three years of warranty, which is slightly lower compared to other tankless water heaters we listed beneath.


Easy to install, small and easily fitting, energy-saving, easy electronic temperature control


Not ideal for large rooms, shorter warranty.

9. Rheem RTEX 13


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

The RTEX-13 model succeeds over RTE 13, which was one of the best electronic tankless water heaters at its time. It is great for compact homes and offices because of its small and easily-fitting everywhere size, as well as in smaller apartments. It wins the Consumer list because of its great energy-efficiency listed at 99.8%, similarly to the Rheem RTEX 18 we listed above. It is also equipped with an external thermostat, which helps users determine the pace of heating up as well as the temperature levels, with absolute control over the temperature. Users can also make adjustments on 1F degree increment. You can opt for the temperatures between 80F and 140F, with a maximum of 4.0 GPM water flow. It is not suitable for multiple simultaneous showers, although it should be more than enough in delivering great performance for one shower and a kitchen or a bathroom sink. Other great features mean that it’s great for those who are looking for affordable price, while also boasting unique and easy-to-assemble design.


Easy to install, compact, affordable, fast performance


Can’t maintain two showers simultaneously.

10. Stiebl Eltron Tempra 29 Plus


  • Price: $$$
  • Weight: 10.39 pounds
  • Dimensions:
    16.5 x 4.6 x 14.5 inches
  • Warranty: 7 years

The last on our list, but nonetheless important, is the Stiebel Eltron Tempra 29 Plus, which produces high-quality water flow, although it’s more expensive compared to the other models we listed. If you own a large house, office or an apartment, it is a great investment. The Tempra 29 Plus comes with a digital temperature display that is equipped with a knob that can adjust the temperature changes in output for the entire house where it’s installed, with users being able to make adjustments from between 86 degrees to 140 degrees. Also, there is a 3.0 GPM at 40F, with addition to 6.5 GPM at 75 degrees. That said, the water flow it can provide depends on the location and the temperature, although it is designed for both warmer and northern, colder areas. It comes with a 7 years warranty, as well as 3 years warranty for its separate parts. Another great thing about it is that it’s compact and operates silently. It is also equipped with advanced energy-saving settings.


Silent, compact, high-performing, advanced display, provides simultaneous shower support, energy-efficient.