Best Electric Tankless Water Heater: Tested and Reviewed

Finding the best electric tankless water heater can feel like searching for a needle in a haystack, especially with so many options available. Whether you’re upgrading from a traditional tank or installing one for the first time, choosing the right model is essential to ensure endless hot water, energy efficiency, and long-term reliability. In this guide, we’ve tested and reviewed the top electric tankless water heaters to help you make an informed decision. From performance and energy savings to durability and features, we’ve covered everything you need to know to find the perfect fit for your home.

List of the Best Electric Tankless Water Heater:

Check out the thorough review of the best electric tankless water heater below.

1. Rheem 18kW 240V Electric Tankless Water Heater

The Rheem 18kW 240V Tankless Electric Water Heater is a compact yet powerful solution for delivering on-demand hot water while optimizing energy efficiency. With dimensions of 14.5 inches in width and 18.25 inches in height, this unit is 90% smaller than traditional tank models, making it ideal for saving space in homes or offices. Designed with a flow rate of up to 4.4 GPM, it can supply continuous hot water for single to mid-range whole-home applications, such as a shower and sink running simultaneously.

Equipped with advanced self-modulating technology, this water heater adjusts power usage based on demand, ensuring minimal energy consumption and significant cost savings. According to the Department of Energy, you can save up to 50% on water heating costs compared to traditional tank models. Its durable copper immersion heating elements are field-serviceable, ensuring longevity and easy maintenance.

The digital thermostatic control with an LED display allows for precise temperature adjustments (+/-1°F), providing optimized comfort. Installation is straightforward with bottom 3/4-inch NPT water connections and threaded components for easy replacement.

Key Features

1. Compact Design: Measures 14.5″W x 18.25″H, perfect for tight spaces.
2. Energy-Efficient: Self-modulating technology cuts water heating costs by up to 50%.
3. Continuous Hot Water: Flow rate up to 4.4 GPM ensures consistent supply.
4. Digital Control: LED display for precise temperature management.
5. Durable Build: Copper heating elements for longevity and field serviceability.

Pros

• Saves energy with on-demand heating.
• Compact and space-saving.
• Easy installation and maintenance.
• Accurate temperature control with LED display.
• High flow rate suitable for single to mid-range applications.

Cons

• Requires a high-capacity electrical breaker.

2. Rheem RTEX-24 24kW 240V Electric Tankless Water Heater

The Rheem RTEX-24 24kW 240V Electric Tankless Water Heater delivers efficient, on-demand hot water for whole-home applications. With a compact size of 17.63″W x 18.25″H, this sleek and modern unit fits in tight spaces while offering a high flow rate of up to 5.9 GPM. This is sufficient to power two showers and two sinks simultaneously in warmer climates, making it a reliable choice for mid-sized households.

Its self-modulating power control ensures energy efficiency by adjusting power usage based on demand, which can reduce water heating costs by up to 50%. The digital temperature display with an ON/OFF dial allows for precise adjustments, ensuring optimal comfort with every use.

Installation is simplified with bottom 3/4-inch NPT water connections, and the unit’s design eliminates the need for venting, making it suitable for nearly any indoor location. Built with stainless steel heating elements, the RTEX-24 is both durable and easy to maintain.

Key Features

1. Flow Rate: Provides up to 5.9 GPM for whole-home applications.
2. Energy Efficient: Self-modulating technology reduces energy consumption.
3. Compact Design: Small footprint suitable for various installation spots.
4. Durable Build: Stainless steel heating elements ensure longevity.
5. Digital Control: LED display enables precise temperature adjustment.

Pros

• Consistent, endless hot water supply.
• Energy savings of up to 50%.
• Space-saving and easy to install.
• High flow rate for multiple fixtures.
• No venting required.

Cons

• Performance decreases in colder climates.

3. EcoSmart ECO 18 Electric Tankless Water Heater

The EcoSmart ECO 18 Electric Tankless Water Heater is a reliable and efficient solution for providing on-demand hot water in small homes, apartments, or larger point-of-use applications. Measuring just 14″W x 17″H x 3.5″D and weighing 14 pounds, its compact and sleek design saves up to 12 cubic feet of storage space compared to traditional tank water heaters. With a power output of 18 kW at 240 volts, it delivers a flow rate of 1.8 to 4.3 gallons per minute (GPM), depending on inlet water temperature, making it suitable for climates where incoming water temperatures are 62°F and above.

Equipped with patented self-modulating technology, the ECO 18 adjusts power consumption based on demand, enabling users to save up to 60% on water heating costs. The digital temperature control allows precise adjustments in 1-degree increments, providing consistent and personalized comfort. For installation, it requires 2 x 40 AMP breakers and 2 x 8 AWG wires, ensuring compatibility with most home electrical systems.

This unit is ETL-listed and certified for lead-free compliance, guaranteeing safety and durability. With a lifetime warranty for residential use, it offers peace of mind and long-term reliability.

Key Features

1. Compact Size: Saves 12 cubic feet of space with dimensions of 14″W x 17″H.
2. Energy Efficiency: Patented self-modulating technology reduces water heating costs by up to 60%.
3. Flow Rate: Provides 1.8 to 4.3 GPM, depending on inlet temperature.
4. Precise Control: Digital temperature control in 1-degree increments.
5. Durable Design: Lifetime warranty for residential use and lead-free compliance.

Pros

• Space-saving, lightweight design.
• Significant energy savings.
• Consistent hot water on demand.
• Easy installation process.
• Precise temperature adjustments.

Cons

• Limited performance in colder climates.

4. Stiebel Eltron 239223 Electric Tankless Water Heater

The Stiebel Eltron Tempra 29 Plus Tankless Water Heater is a premium solution for on-demand, energy-efficient hot water. With a compact design measuring 16.63″W x 14.5″H and weighing 24 pounds, this unit saves valuable space while eliminating the need for venting. Powered by 28.8 kW at 240 volts, it delivers a continuous supply of hot water with a flow rate up to 4.5 GPM, depending on the inlet water temperature. Ideal for medium to large households, it can handle multiple fixtures simultaneously without compromising performance.

This water heater features Advanced Flow Control technology, a German-engineered system that adjusts water flow to maintain consistent temperatures, ensuring uninterrupted hot water even during high demand. It reduces energy consumption by 15-20% compared to conventional tank water heaters, eliminating standby heat loss. The digital temperature control with two memory presets offers personalized settings, enhancing convenience and comfort.

The unit requires hard wiring with three dedicated 40-amp breakers and a minimum 200-amp household electric service, making it best suited for homes with robust electrical systems. Certified for lead-free compliance and built with durable copper components, it ensures reliability and safety.

Key Features

1. Advanced Flow Control: Maintains consistent water temperature by adjusting flow during high demand.
2. Energy Efficiency: Uses 15-20% less energy compared to traditional tank water heaters.
3. Compact Design: Saves space with no venting required.
4. Customizable Settings: Digital control with two temperature memory presets.
5. Certified Quality: ANSI/UL Std. 499 and NSF/ANSI 372 lead-free compliance.

Pros

• Provides continuous and unlimited hot water.
• Reduces energy consumption and eliminates standby heat loss.
• Space-saving design suitable for modern homes.
• Durable copper heating elements ensure long-term performance.
• Simple installation with clear instructions.

Cons

• Requires a robust 200-amp electrical service.

5. thermomate Electric Tankless Water Heater

The thermomate 18kW Tankless Electric Water Heater offers an efficient, on-demand hot water solution for residential whole-house applications. Compact at 13.12″W x 17.12″H, this unit eliminates the need for a traditional water tank, saving floor space and fitting seamlessly into tight areas. With a maximum operating pressure of 150 PSI and a power output of 18kW, it provides hot water in as little as three seconds, ensuring a continuous supply for showers and faucets without running out.

Equipped with self-modulating technology, this water heater adjusts energy consumption based on incoming water temperature and flow rate, achieving 99.8% energy efficiency. It saves up to 60% on water heating costs compared to traditional tank models. The digital temperature display allows precise control in 1°F increments, ranging from 80°F to 140°F. Additionally, its innovative heating element design reduces scale buildup and corrosion, ensuring durability and low maintenance.

Safety is a priority with overheating protection, auto shutoff in case of no water, and leak-resistant construction. Installation is straightforward, but it requires two 40-amp breakers and 8 AWG wiring.

Key Features

1. Instant Hot Water: Provides endless hot water in as little as three seconds.
2. Energy Efficiency: Self-modulating technology delivers 99.8% efficiency.
3. Compact Design: Wall-mounted and space-saving for tight installations.
4. Smart Controls: Digital temperature adjustment in 1°F increments.
5. Durable Build: Innovative heating element reduces maintenance needs.

Pros

• Continuous and instant hot water supply.
• Saves up to 60% on water heating costs.
• Compact and wall-mounted design.
• Easy-to-use digital temperature controls.
• Built-in safety features for overheating and leaks.

Cons

• Requires specific electrical setup (80-amp breaker and 8 AWG wiring).

6. Ecosmart ECO 36kw 240V Electric Tankless Water Heater

The EcoSmart ECO 36 Electric Tankless Water Heater is a robust solution for delivering on-demand hot water in large residential settings. As EcoSmart’s most powerful model, this unit operates at 36 kW with 240 volts, offering a flow rate between 3.6 and 8.7 GPM, depending on the inlet water temperature. Its advanced self-modulating technology ensures energy efficiency, adjusting power usage based on demand. This results in up to 50% savings on water heating costs compared to traditional tank heaters.

Designed for versatility, the ECO 36 can handle up to two showers simultaneously in colder climates (inlet temperatures as low as 37°F) and up to four showers and a sink in warmer climates, making it ideal for larger households. With a 99.8% energy efficiency rating, it significantly reduces heat loss, while its sleek, wall-mounted design saves up to 90% of the space traditional tanks require.

Equipped with a digital temperature control, users can precisely set water temperatures in 1-degree increments for personalized comfort. Installation requires 4 x 40A breakers and 8 AWG wiring, making it compatible with homes with a 150-amp electrical service.

Key Features

1. High Flow Rate: Delivers 3.6–8.7 GPM depending on inlet temperature.
2. Energy Efficient: 99.8% efficiency with self-modulating technology.
3. Compact Design: Saves up to 90% of the space compared to traditional tanks.
4. Precise Control: Digital display with 1-degree temperature adjustments.
5. Versatile Usage: Suitable for colder and warmer climates, supporting multiple fixtures.

Pros

• Provides continuous and endless hot water.
• Saves up to 50% on energy costs.
• Space-saving, sleek wall-mounted design.
• Handles high-demand applications in larger homes.
• Durable stainless steel and copper components.

Cons

• Requires a 150-amp electrical service.

7. Rheem 13kW 240V Electric Tankless Water Heater

The Rheem RTEX-13 Residential Tankless Water Heater is a compact, energy-efficient solution designed for small homes and point-of-use applications. Operating at 13 kW and 240 volts, this unit delivers a maximum flow rate of 3.17 GPM, making it ideal for low-demand applications like a shower and sink running simultaneously. With a 99.8% energy efficiency rating, it minimizes energy waste, saving on utility costs while providing consistent hot water.

This model features external digital thermostatic control with an LED display, allowing users to adjust the water temperature in precise 1°F increments. Its durable copper immersion heating elements are field-serviceable, ensuring long-lasting performance and low maintenance. Installation is straightforward, thanks to the 1/2-inch NPT adapters and compression water connections. The inclusion of a water-saver shower head (1.5 GPM) further enhances efficiency by reducing water usage.

Key Features

1. Compact Design: Ideal for point-of-use and small home applications.
2. Energy Efficiency: 99.8% efficiency reduces energy costs.
3. Flow Rate: Provides up to 3.17 GPM for simultaneous use of a shower and sink.
4. Precise Temperature Control: Adjustable in 1°F increments with LED display.
5. Durable Heating Elements: Copper immersion elements ensure longevity.

Pros

• Compact and space-saving design.
• High energy efficiency saves on utility costs.
• Easy to install with included adapters and connections.
• Precise and user-friendly temperature adjustments.
• Affordable and reliable for low-demand households.

Cons

• Limited capacity for high-demand applications.

8. Rheem 11kW 240V Electric Tankless Water Heater

The Rheem 11kW 240V Tankless Electric Water Heater is a compact and energy-efficient option designed for point-of-use applications. Measuring just 8.25″W x 12.63″H and weighing 3.2 kilograms, this unit is 90% smaller than traditional tank water heaters, making it an excellent choice for tight spaces, such as under sinks or in small bathrooms. With a maximum flow rate of 2.68 GPM, it provides reliable and continuous hot water on demand, ideal for single-use fixtures or light simultaneous usage.

Equipped with self-modulating power control, the RTEX-11 adjusts energy consumption based on water flow and demand, ensuring optimal efficiency. Its digital temperature display allows precise adjustments, delivering consistent comfort and control. The unit’s stainless steel heating elements ensure durability and long-lasting performance while minimizing maintenance needs.

Installation is straightforward, thanks to side 1/2-inch NPT water connections, and no venting is required, allowing placement virtually anywhere in the home.

Key Features

1. Compact Size: Fits tight spaces with dimensions of 8.25″W x 12.63″H.
2. Energy Efficiency: Self-modulating technology minimizes energy waste.
3. Flow Rate: Provides up to 2.68 GPM for point-of-use applications.
4. Durable Build: Stainless steel heating elements reduce maintenance.
5. User-Friendly: Digital temperature control ensures precise adjustments.

Pros

• Compact and space-saving design.
• Continuous and consistent hot water supply.
• High energy efficiency reduces utility costs.
• Easy installation with no venting required.
• Durable stainless steel components.

Cons

• Limited capacity for multiple fixtures.

​How to Choose the Best Electric Tankless Water Heater?

Understand Your Hot Water Needs

The first step in choosing the best electric tankless water heater is understanding your household’s hot water demand. Do you need hot water for multiple showers running simultaneously? Or just for a single sink?

Tankless water heaters are sized based on flow rate (measured in gallons per minute or GPM) and temperature rise (how much they can heat incoming water). For instance:

• A shower typically requires 2–3 GPM.
• A dishwasher uses about 1–2 GPM.

Make a list of the appliances you’ll use at the same time and add up their GPM to determine your total flow rate. This step ensures you won’t end up with cold water surprises!

Check the Incoming Water Temperature

Your location plays a huge role in deciding the right unit. If you live in colder climates, where groundwater temperature is lower, your water heater will need to work harder to reach your desired temperature.

For example, if your incoming water is 50°F and you want it at 120°F, you’ll need a water heater with a higher temperature rise capacity. Many manufacturers provide temperature rise charts—take a look before you buy.

Energy Efficiency Matters

One of the biggest advantages of electric tankless water heaters is energy efficiency. Look for units with a high Energy Factor (EF) or Uniform Energy Factor (UEF)—these ratings indicate how efficiently the unit converts electricity into heat. The higher the rating, the more you’ll save on energy bills over time.

Plus, many models are designed to heat water on demand, eliminating the standby energy losses associated with traditional tank heaters.

Choose the Right Size and Power Capacity

Electric tankless water heaters come in different sizes and power capacities. Consider the following factors:

• Point-of-use heaters: Ideal for small spaces, like a single bathroom or sink.
• Whole-house units: Designed for multiple fixtures, perfect for large households.

Check the unit’s kilowatt rating (kW). A higher kW means the heater can handle more water demand. For example, a 24kW unit may be suitable for 2–3 bathrooms, while an 8kW unit is better for a single fixture.

Look for Special Features

Not all water heaters are created equal—look for features that add convenience and improve performance:

• Digital temperature controls: Allow you to set the exact water temperature for comfort and safety.
• Self-modulating technology: Adjusts power usage based on demand, increasing energy efficiency.
• Durability: Models with stainless steel or copper heating elements last longer and resist corrosion.

Installation Requirements

Before making your final decision, consider installation requirements. Electric tankless water heaters often need a dedicated circuit breaker and wiring upgrades. Check your home’s electrical panel to ensure it can handle the load.

Also, think about where the unit will be installed. Compact models can fit under sinks or in tight spaces, but whole-house units may need more room.

Budget and Long-Term Costs

While electric tankless water heaters can cost more upfront than traditional tanks, they offer significant savings in the long run. Consider the initial price, installation costs, and ongoing energy savings.

For those on a budget, compare models with similar specifications to find the best value. Don’t forget to check for rebates or incentives in your area—they can make energy-efficient upgrades more affordable.

Why an Electric Tankless Water Heater is a Smart Choice?

Switching to an electric tankless water heater not only saves energy but also offers convenience and endless hot water. Unlike traditional water heaters that store gallons of water, tankless models heat water only when you need it—no more worrying about running out during a busy morning!

With their compact design, they also save space, making them a great choice for apartments or smaller homes.

Make Your Choice with Confidence

By now, you should feel more confident about choosing the best electric tankless water heater for your home. Remember to evaluate your household’s hot water needs, check energy efficiency, and compare models based on features and price.

Frequently Asked Questions When Selecting the Best Electric Tankless Water Heater

1. What is an electric tankless water heater?

An electric tankless water heater is a device that heats water on demand without storing it in a tank. Unlike traditional water heaters, it heats the water as it flows through the unit using electric heating elements. This ensures a continuous supply of hot water and reduces energy waste caused by standby heating.

2. How do I determine the right size for my needs?

To choose the right size, calculate your household’s hot water demand during peak usage. Determine the total gallons per minute (GPM) required by summing up the flow rates of appliances and fixtures you’ll use simultaneously (e.g., showers, faucets, and dishwashers). Also, consider the temperature rise needed, which depends on your incoming water temperature and your desired hot water temperature.

3. Are electric tankless water heaters energy-efficient?

Yes, electric tankless water heaters are highly energy-efficient because they only heat water when needed, eliminating standby energy losses. Most models have high Energy Factor (EF) or Uniform Energy Factor (UEF) ratings, meaning they convert a large percentage of electricity into heat.

4. What are the advantages of an electric tankless water heater over a traditional tank model?

Electric tankless water heaters offer several advantages:

• Endless hot water supply.
• Compact size, saving space in your home.
• Reduced energy consumption due to on-demand heating.
• Longer lifespan compared to traditional water heaters.

5. Do electric tankless water heaters work in cold climates?

Yes, but you need to choose a model with sufficient power (kilowatt rating) and temperature rise capacity to handle colder incoming water. In regions with freezing temperatures, a higher-powered unit is essential to ensure adequate performance.

6. What are the installation requirements for an electric tankless water heater?

Electric tankless water heaters typically require:

• A dedicated circuit breaker.
• Upgraded wiring to handle higher electrical loads.
• Adequate space near the water line for installation.
  Consult a licensed electrician to assess your home’s electrical panel and make any necessary adjustments before installation.

7. How long does an electric tankless water heater last?

With proper maintenance, an electric tankless water heater can last 20 years or more, which is significantly longer than traditional tank water heaters. Models with durable components, such as stainless steel or copper heating elements, tend to have an even longer lifespan.

8. Can an electric tankless water heater supply hot water to multiple fixtures at once?

Yes, but the unit must have a high enough flow rate (GPM) and power capacity (kW) to handle simultaneous demands. For large households or multiple bathrooms, consider a whole-house model or installing multiple point-of-use units for specific fixtures.

9. Are electric tankless water heaters expensive to operate?

Operating costs depend on your household’s hot water usage and local electricity rates. Electric tankless water heaters are generally cost-effective because they eliminate standby energy losses and only heat water when needed. Over time, they can reduce your utility bills compared to traditional tank water heaters.

10. Do I need regular maintenance for an electric tankless water heater?

Yes, regular maintenance is important to keep your unit running efficiently. This includes:

• Descaling the unit annually (or more frequently in areas with hard water).
• Cleaning or replacing filters.
• Inspecting the heating elements for wear and tear.

Following the manufacturer’s maintenance recommendations will help extend the lifespan of your unit.

11. What are the key features to look for in the best electric tankless water heater?

When choosing an electric tankless water heater, prioritize these features:

• Flow rate and temperature rise capacity suitable for your needs.
• High Energy Factor (EF) or Uniform Energy Factor (UEF).
• Digital temperature controls for precision.
• Self-modulating technology for energy efficiency.
• Durable materials like stainless steel or copper heating elements.

12. Are electric tankless water heaters environmentally friendly?

Yes, electric tankless water heaters are environmentally friendly because they reduce energy consumption and carbon emissions. Unlike gas models, they don’t produce combustion gases, making them a cleaner option for eco-conscious households.

13. Can I install an electric tankless water heater myself?

While some homeowners with electrical experience may attempt a DIY installation, it’s recommended to hire a licensed electrician. Incorrect installation can lead to safety issues or inefficient operation, so professional expertise ensures the job is done correctly.

14. What is the cost of an electric tankless water heater?

The cost varies depending on the brand, size, and features. Small point-of-use units can start at $150–$300, while whole-house models range from $500 to $1,500 or more. Installation costs vary but typically range from $300 to $1,000, depending on electrical upgrades needed.

15. How do I know if an electric tankless water heater is right for me?

An electric tankless water heater is ideal if you want an energy-efficient, space-saving solution with endless hot water. It’s especially suitable for households with moderate water demand or homes without access to gas lines. However, ensure your home’s electrical system can support the unit’s requirements.

Conclusion

After testing and reviewing the best electric tankless water heaters, it’s clear that the right choice depends on your household’s specific needs, such as water demand, climate, and budget. Whether you’re looking for a compact point-of-use model or a powerful whole-house unit, these heaters offer an energy-efficient and space-saving solution for modern homes.

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