3 Best Outdoor Electric Tankless Water Heater Reviews & Experts Guidance

The electric tankless water heater is mainly powered by electric, no pipeline and venting kits are needed, therefore, the installation position of it is quite flexible. Most of the electric tankless water heaters can also be installed outdoor. But you need to make sure that some protection needs to be added for outdoor electric tankless water heater, or the severe weather may shorten the using life of it.

In this article, we would like to give you detailed reviews for the best outdoor electric tankless water heater, in order to help you choose the most suitable one based on your situation.

The 3 Best Outdoor Electric Tankless Water Heaters in 2020

#1. Overall Best Type – Stiebel Eltron Tempra Tankless Water Heater 

#2. Runner Up – EcoSmart ECO 27 Electric Tankless Water Heater

#3. Best Point of Use – Sio Green IR260 Electric Tankless Water Heater

How to Pick the Best Outdoor Electric Tankless Water Heater?

When purchasing an electric water heater for an outdoor shower, there are factors that you should put into consideration. Have a look at some of them:

The cost

The cost of an electric water heater varies from one brand to another, depending on the power input. The prices range from $150 to $1,500. You should, therefore, choose what can serve you well. Do not go for something that you are not going to make use of competently. If possible, go for something cheaper as long as it serves your needs. Do not be confused by famous brands, which tend to be very expensive.

The material

Remember, this is an outdoor shower. Therefore you should ensure that you go for some sturdy material that is rust-resistant. Stainless still can serve this purpose. If you go for materials that cannot stand all weather, you will end up replacing it without enjoying its service. Stainless still can serve better for the showerhead.

The water pressure needed

You also have to consider the water pressure that the heater will need. If you are living in a warm temperature place, you might opt for a low water pressure heater so that one can have a good time in the shower. Generally, if it is just for the sake of showing, there is no need for a heater that needs high-pressure water.

Comparison Chart of Top Rated Outdoor Electric Tankless Water Heaters

Top 3 Best Outdoor Electric Tankless Water Heater Reviews

1. Best For Large Home – Stiebel Eltron Tempra 20 Plus Electric Tankless Water Heater

Stiebel Eltron Tempra series of electric tankless water heater is an improvement version, compared with original Eltron types, this series has a digital temperature display and is able to keep the water temperature constant with the Advanced Flow Control. All other series including Tempra 12 Plus, 15 Plus, 20 Plus, 24 Plus, 29 Plus, and 36 Plus are all in excellent working performance, they differ in required voltage only.

best outdoor electric tankless water heater
outdoor electric tankless water heater


  • Low working noise

Do you still feel it annoying in loud heating noise in your bathroom or kitchen? This unit is proved to be extremely quiet, you can hear no working noise in the process at all. And stylish compact size occupies little space on your outdoor wall.

  • Endless hot water

For the tank water heater, if you use hot water for a long time, the heated hot water will run out soon. But the instant outdoor electric heater is different, you can never run out of the hot water and it heats water fast.

  • Advanced Flow Control

The advanced flow control technology is able to smartly and automatically maintain the water temperature, enabling to give steady hot water for you in bathing or washing.


  1. Save at least 15-20% on the electric bill
  2. Support full power modulation
  3. Auto modulation technology
  4. Has the power to provide about 5 gallons water per minute, high flow rate machine
  5. High-level electronic parts and a reliable cover
  6. Able to support one or two bathrooms and kitchen faucet the same time
  7. The most technologically advanced electric water heater
  8. 99% energy, nearly no water is wasted.
  9. Built-in advanced flow control modules, to regulate the water pressure automatically


Difficult to install, need 240 v power and heavy-duty wiring

2. Best For Indoor and Outdoor Use – EcoSmart ECO 27 Electric Tankless Water Heater

EcoSmart Eco 11, 18, 27, and 36 series are all best outdoor electric tankless water heaters on the market in 2020, especially for the Eco 27, which is on the hot-selling lists for a long period of time. They can be installed both indoor and outdoor. The nearer installation is, the faster hot water gets. So for outdoor installation, you can install it on the outside bathroom wall.

tankless water heater outside
outdoor tankless water heater


  • 140 degrees F temperature

This unit is perfect to be used in Northern America, where the incoming water temperature reaches as low as 37 degrees F; when in such low temperature, EcoSmart is still able to heat nearly 3 gallons per minute of water.

  • Multiple points of use

This unit is able to handle up to 6 gallons of water per minute, the official boasts that it is able to run 4 showers and one kitchen sink the same time and never run out of hot water.

  • Money saver

This outdoor tankless water heater is capable of saving up to 50% in water heating costs, the small shape also helps save much space for you. Advanced self-modulating technology controls water temperature smartly.


  1. Digital temperature control
  2. Copper and stainless steel components
  3. Unit is well made, heating elements are easy to be replaced
  4. Save 12 cubic feet after installation
  5. Save about 50% in water heating cost
  6. Self-modulating technology to ensure heater draws energy only when using it


  1. Disappointed service
  2. The temperature can not be set as right as EcoSmart promises

3. Best Cheap – Sio Green IR260 Electric Tankless Water Heater

outdoor electric tankless water heater
top rated outdoor tankless water heaters


  • No corrosion

It has patented technology to ensure that an outdoor electric tankless water heater gets no direct contact with metals. It will, in turn, prevent corrosion, limescale deposit, and calcium buildup. Therefore, it needs no or less maintenance later using time.

  • 4 power levels

There are altogether 4 power levels that can be adjusted, so you can choose the most suitable one for your family needs. The temperature of the water can also be adjusted easily. The LCD screen shows temperature accurately.

  • Infrared heating design

It has an infrared heating design to heat water only when you need it, and the fast heating time enables you to enjoy constantly hot water any time you want.


  1. Manual 4 power level
  2. Easy temperature adjustment
  3. Quick and easy installation
  4. No corrosion, no coils, and no scaling
  5. Stylish compact design


It is perfect to be used as a point of use but not whole-house type

The above three are the best outdoor electric tankless water heaters we recommended for you, they are on the top list on the market of 2020 and all the performance is in brilliant condition. Of course, there are also many other types you can choose on Amazon, you can check for more information and price details on Amazon if you have an interest.

Benefits of Installing Electric Tankless Water Heaters Outdoors

Easy Installation

Tankless water heaters are perfect for outdoor installation. That is because you do not have to alter the structure of your property. Also, there is venting. Ideally, for outdoor tankless water heaters, you need shorter or no venting at all. Moreover, since the unit’s components do not condense, you do not require a drainage system. This is good if you do not have drainage in your home. You should note that improper drainage is known to cause damage to the heater exchangers.

Extends Lifespan

When your electric tankless water heater has all the required protection, it needs from wind, rain, sun, and cold, it lasts longer than indoor models. It is advisable to use enclosures made of aluminum as they are rustproof. Moreover, all components within the water heater are meant to withstand harsh elements.

Less Risk of Leaks

When you install a water heater indoors, there is a chance that it will leak. Although the leakage will be minimal as compared to a broken tank water heater. Nevertheless, it will cause damage, especially during the end of its life. On the other hand, when you install the water heater indoors, the leaks are not a problem.

Where Should a Tankless Water Heater Be Installed Outdoors?

You should note that hot water time is influenced by the performance of the heating machine. Also, it is influenced by the installation position. Therefore, you can shorten the waiting time to a large extent and save on electricity and water costs by installing it in the right place. For instance, you can install it wherever you want to use it or outside the bathroom wall. Due to the compact size, you can even install it under sinks, storage areas, and even closets.

Do Tankless Water Heaters Have to Be on an Outside Wall?

An outside tankless water heater frees up a lot of indoor space. Remember that tankless units can withstand below-freezing temperatures because of the self-warming components. That means you can install them outside if you live in warmer climates. Moreover, installing a tankless water heater frees up a lot of space and does not need additional venting.

You should note that a tankless water heater is designed to support multiple venting options. For instance, it can vent through a side wall, creating a lot of flexibility and options for the placement. You should note that gas tank heaters vent through the roof. However, tankless units blow exhaust horizontally.

Which is Better for An Outdoor Shower, a Gas or Electric Tankless Water Heater?

For an outdoor shower, an electric tankless water heater tends to be better than the gas heater. First, the electric one is cheaper than the electric one. The cost of operating an electric heater is lower than that of a gas. Additionally, the electric heater is safer than the gas heater, placing it outdoor means that multiple people will use it. Even kids can end up using it. Therefore, you ought to check at the safety. If that is the case, an electric heater is better for an outdoor shower than a gas heater.


Can indoor electric tankless water heaters also install outdoor?

Electric tankless water heaters are powered by electric only, no pipeline or venting kits are needed. Thus you can freely install them anywhere you want. But for some specific outdoor tankless water heaters, manufacturers suggest they should be used only for outdoor, if in such occasion, you can not use it as indoor types. On the contrary, the indoor tankless water heater can not be installed outdoor with specific requirements also.

If you are not sure, you can ask the manufacturer for help, they will help you a lot on installation.

How to Use Outdoor Electric Tankless Water Heater Safely?

The hot water waiting time is determined by the performance of the heating machine, but it is also greatly influenced by the installation position; if you install it far away from using spot, then hot water needs to take a few seconds to flow through the pipe.

Therefore, for an outdoor electric tankless water heater, we suggest it be installed outside the wall of a bathroom or wherever you intend to use water, thus the waiting time can be shortened to a large extent, and water or electricity costs can be saved accordingly.


Tankless Water HeaterBest Type
Best one for commercial useStiebel Eltron Tempra 20 Plus Electric Tankless Water Heater
Smallest and lightest typeEcoSmart ECO 27 Tankless Water Heater
Best point of use typeSio Green IR260 Electric Tankless Water Heater

If you want to get more information on product price, performance, and dimensions, etc, please feel free to check on Amazon, and there will always be a large discount on it to help save a large sum of money for you.


David: Penn State-educated Mechanical Engineer and Business-savvy Fluid Dynamics Specialist. Balances family plumbing business support with a thriving engineering career at a top, undisclosed company. (they want it that way) I help Will with plumbing and HVAC needs on his Real Estate.

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