Best Electric Tankless Water Heater

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An electric tankless water heater is an energy and space-saving system that provides your home or other environments with hot water on demand. Unlike traditional heaters, it does not have a storage tank and will only heat the water on demand.

Today, the market has a wide range of tankless water heaters that vary in physical size, energy consumption, capacity, and other features. Whether you want hot water for a single sink, a shower, or multiple applications, there is the right system for you in the market. 

7 best electric tankless water heaters

With so many options, most customers have a challenge making the right purchase decision. To make it easier for you and ensure that you choose a system that meets your requirements, here is a list of the best electric tankless water heaters.

iheat AHS27D tankless water heater 

The iHeat AHS-27D is a heavy-duty 27KW electric tankless water heater that can serve a whole house while providing several outlets simultaneously. Employing an advanced water heating self-modulating technology, the space-saving heater achieves 99% energy efficiency. Its 3/4 inlet and outlets support high water flow rates hence ensuring the right amount of hot water at the faucets. For example, it can supports 2 to 4 showers simultaneously in warm climates. 

Ideally, the iHeat AHS-27D is suitable for high demanding applications such as multi-family dwellings, hospitals, commercial installations, apartments, etc. It has advanced electronic controls for high comfort, safety, and energy efficiency. 

Additionally, the iHeat enclosure and heat exchanger are built with an ASTM 304 stainless steel, hence suitable for normal as well tough and rugged applications. Consequently, this ensures longer service life without the risk of corrosion or sedimentation.   

Proprietary inbuilt iHeat software and the high-speed USB ports allow the maintenance personnel to easily monitor the system and run full diagnostics without disassembling or opening up the heater.

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Ecosmart ECO 27 electric tankless water heater

Ecosmart ECO 27 electric tankless water heater
Ecosmart ECO 27 electric tankless water heater

Ecosmart ECO 27 is a compact and visually appealing tankless heater that can fit in a wide range of spaces. It has a self-modulating control technology that adjusts the pressure and energy usage to maintain a safe and consistent supply of hot water regardless of the input. Consequently, this increases the heating efficiency and energy savings. 

The heater has digital temperature control and a display while the hot water can reach a maximum of 140 degrees. Also, the Ecosmart tankless heater has a large capacity to supply multiple fixtures simultaneously, hence suitable for medium-sized homes and other demanding applications in both cold and warm climates. 

Its flow rate ranges between 2.7 and 6.5 GPM depending on the temperature of the incoming water. For example, it comfortably delivers 3GPM in cold climates inlet water at 37 degrees F. For warmer climates, it does 6GPM.

Generally, the 27 KW heater comes with three 9KW heating elements, each of which require a separate 40 A circuit and electrical service of about 200A for the entire system. 

The durable copper and stainless steel building materials ensure durability, reliability, and longer service life. Additionally, the parts are easily replaceable, and the system comes with a lifetime warranty. 

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Rheem RTEX-18 electric tankless water heater

Rheem RTEX-18 is a powerful, yet one of the easiest to install residential tankless water heaters. With a 240 v supply, the 18 KW, 4.4 GPM heaters are suitable for households with multiple applications since they can support at least two showers or faucets simultaneously.

The heater supports 360-installation hence allowing you to place it anywhere you want within the house. Further, its thin exterior dimensions allow you to slide and fit it anywhere, including small or confined spaces, so you do not have to worry about lack of space. 

Besides aesthetically appealing exterior and sleek design, the Rheem RTEX-18 is a durable tankless water heater with a strong mechanism that uses long-lasting copper and brass metals. 

Additionally, the readily available and easy to replace parts make it easy to maintain. Moreover, even replacing the threaded metal parts of the mechanism is also easy, so you do not have to worry about complicated and expensive maintenance.

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Stiebel Eltron Tempra 24 Plus Electric Tankless Water Heater

The Stiebel Eltron Tempra 24 Plus is a reliable, 24 K, 240V tankless water heater with advanced flow control (AFC) to manage the hot water output. Usually, the AFC automatically adjusts the heater to main a consistent temperature and pressure hence enhancing comfort.

Additionally, the heater has a compact and sleek space-saving design that is easy to install. An easy-to-use dial and digital display allow you to adjust and monitor the temperature. 

Suitable for residential and commercial use, the Tempra 24 is a compact system that takes less space while delivering endless hot water and energy savings. Additionally, the heater is made of corrosion-resistant material hence more reliability and longer service life. 

As a 24 KW system, it requires about 150A electric service. The long-lasting energy-saving heater, with an output temperature range of 68-140o F, comes with 3-year parts and 7-year leakage warranties.

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Ecosmart ECO 18 tankless water heater

The Ecosmart ECO 18 is a compact, easy to install, and durable tankless water heater. It has a self-modulating technology that helps to optimize energy use and efficiency. Additionally, it has a temperature control knob to help you adjust the water to your liking. 

Ecosmart ECO 18 tankless water heater

The 2.5 GPM budget tankless water heaters support up to two simultaneous showers in warmer climates. Generally, the ECO 18 is suitable for condominiums, entire homes, apartments, and other installations that require hot water for multiple applications.

The Eco 18 has three electric heating elements, each of which requires its separate electrical circuit. However, you do not have to use all of them every time unless you want a lot of hot water quickly. Although the extra heating element enables the unit to provide more hot water quickly, it will increase energy consumption.

 One of the drawbacks of the Ecossmart ECO 18 is that the heating elements corrode faster when working with hard water, – and this results in higher maintenance costs. 

Sio Green 18 infrared tankless water heater

Sio Green 18 v2 is a powerful and efficient 240V, infrared tankless electric water heater. The low-cost, 18 KW environmentally friendly water heater uses patented infrared heating technology, unlike other systems that rely on conduction from the elements.

Sio Green 18 infrared electric tankless water heater

Suitable for both residential and commercial installations, the 0.5-5.0 GPM rate heater is adequate to provide hot water to a large family home as well as a medium and large business environment. Additionally, it has a user-friendly and comfortable temperature range and control. The infrared technology provides superior heating and a 98% energy efficiency that allows you to reduce the electricity bills by up to 65% compared to other electric tankless heaters.

Also, the SIO 18 does not suffer from corrosion and calcium build-up since it does not have exposed metallic components. Finally, compact design and self-cleaning technology help to ease the installation and maintenance tasks.

Rheem RTEX-24

Rheem RTEX-24
Rheem RTEX-24

Rheem RTEX-24 is a powerful and reliable residential electric tankless water heater. The 94% energy-efficient heater, with a simple, user-friendly design and decent appearance for households, provides a consistent supply of hot water. 

Generally, the Rheem RTEX 24 is an easy-to-install tankless water heater that takes only a small space, hence suitable for a wide range of locations. Additionally, it is built with high-quality materials and technology, including a durable copper heating element that guarantees efficiency, reliability, and longer service life. 

Other feature includes a dial adjustment, a digital temperature display, and a self-modulating technology. The heater, with a 5.9GPM, provides consistent hot water on demand. 

What to consider when looking for an electric tankless water heater?

When looking for a tankless electric water heater, here are some of the considerations. 

Energy efficiency

An efficient tankless water heater uses less energy hence lower electricity bills and impacts on the environment. However, do not forget to check performance, capacity, and other features as you look for an efficient system. 

Available space

The model you settle on must have a physical size that fits well in your available space, otherwise, if it is too big, you may need to do some modifications or install it in an inconvenient location.  

Ideally, a model that is compact or smaller than your available spaces gives you some flexibility. However, it is vital to strike a balance between the requirements, size, and cost of the water heater.

Installation process

While some models are easy to install and you can do it by yourself, others require more technical skills and special tools that you might not have. As such, you need to ensure that for models that require professionals, you can get them in your location at reasonable costs; otherwise, you may have to forfeit the warranty or pay more for the installation.


The tankless water heater should have a reasonable hot water capacity to meet your intended use.  

Water flow rate

The water heater’s flow rate should be enough to support your applications. Choose a model with an adequate flow rate depending on your intended usage. If you want to use the hot water for just a sink or single shower, you may go for a smaller rate. Also, note that installing low-flow fixtures allows you to increase the number of hot water points that can run simultaneously even when you have a lower flow rate.

The warranty period and terms

Most often, the warranty period and terms vary from one manufacturer and water heater model to another. Ideally, go for a model with a longer warranty period. Some models come with a lifetime warranty, and these could be the ideal choices if they meet other criteria such as size, efficiency, capacity, and most of your entire budget.

Finally, some manufacturers often give conditions, such as using a qualified installer, accessories, and procedures. Failure to comply with these conditions will void the warranty.