The Best Electric Tankless Water Heaters to Save Space and Cut Costs

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Affordable, relatively easy to install, and able to reduce hot-water costs substantially, an electric tankless water heater provides numerous benefits. This in-depth guide can help shoppers find the best one.

While traditional water heaters remain the best choice for some people, a tankless unit can save space and help reduce your monthly heating bills. This type of water heater provides hot water on demand, when it’s needed. Before switching, though, you’ll want to choose between buying a gas or electric model. High-end gas models are usually more powerful but also cost more and are more challenging to install.

Many homeowners prefer to avoid gas for safety reasons. Tankless gas water heaters typically aren’t as energy efficient as electric models, so that’s another reason to choose an electric tankless water heater.

We’ve used both types in various home remodels. Our best overall pick is the Stiebel Eltron Tempra 36 Trend Tankless Water Heater for its 7.5-GPM flow rate, 99 percent efficiency rating, and auto-modulation function.

To compile this list of the best electric tankless water heaters, we took an in-depth look at the products available and chose them by category based on specifications, features, and customer reviews.

1. BEST OVERALL: Stiebel Eltron Tempra 36 Trend Tankless Water Heater
2. RUNNER-UP: EcoSmart ECOS 27 Electric Tankless Water Heater
3. BEST BANG FOR THE BUCK: Thermomate 18kW Tankless Electric Water Heater
4. BEST FOR SMALL HOMES: EcoSmart ECO 11 Electric Tankless Water Heater
5. BEST FOR LARGE HOMES: Rheem RETEX-36 Performance Tankless Heater
6. MOST VERSATILE: Airthereal 27kW Electric Tankless Water Heater
7. BEST POINT-OF-USE UNIT: Ecotouch Tankless Water Heater
8. BEST FOR CONDOS: Rheem RTEX-13 Professional Classic Water Heater
9. ALSO CONSIDER: Rheem RTEX-18 Professional Classic Water Heater

How We Chose the Best Electric Tankless Water Heaters

We were particularly interested in major advancements in tankless water heater technology in recent years. Systems that respond precisely to demand are now even more efficient than early models. Durability seems to have improved as well. Most of today’s tankless electric water heaters have long life expectancies.

We researched the best electric tankless water heaters in a variety of categories and chose options with high customer satisfaction. We also enlisted help from Raymond Snesrud, founder and CEO of Minneapolis-based water heater installation company Water Heaters Now, to identify what factors matter most when choosing an electric tankless water heater. Examples of features we ultimately considered are maximum temperature, maximum flow rate, efficiency rating, and special features included by the top brands.

Most of the featured units offer water temperatures up to 140 degrees Fahrenheit. The selected water heaters range in flow rates between 1.5 and 7.5 gallons of water per minute (GPM) to accommodate the water needs of various households. Most units have an efficiency rating of 99 percent and above. Additionally, we prioritized water heaters with digital thermostats, durable metal components, and self-modulating technology. A few units are also Underwriters Laboratories (UL) and Canadian Standards Association (CSA) certified for reliable performance.

Our Top Picks

Our top picks come from a variety of leading manufacturers and have been divided into specific categories to make it simple to find the best electric tankless water heater for a particular household or situation.

Best Overall

Stiebel Eltron Tempra 36 Trend Tankless Water Heater

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Product Specs 

• Model: Tempra Trend 36
• Maximum temperature: 140 degrees Fahrenheit
• Maximum flow rate: 7.5 GPM
• Efficiency rating: 99 percent

What We Like

• Equipped with auto-modulation that maximizes heating efficiency, helping to save energy costs
• Nearly silent operation provides enough hot water for 4 simultaneous showers
• Can serve large homes, with a high flow rate of 7.5 GPM

What We Don’t Like

• Some customers complain that the water heater has low water pressure

The Stiebel Eltron Tempra 36 Trend is among the most powerful electric tankless water heaters on the market, providing a maximum of 7.5 GPM, which should provide enough hot water for four showers running simultaneously. It can heat water to 140 degrees Fahrenheit, well above the U.S. Department of Energy’s (DOE) maximum recommendation for household water temperature of 110 degrees Fahrenheit.

This model also is highly efficient. Given that no system is 100 percent perfect, a rating of 99 percent efficiency places the Stiebel Eltron among the best available. Auto-modulation minimizes temperature fluctuations, and the unit runs virtually silently. The preferred temperature can be preset into memory using the unit’s digital display.

This 36 kilowatt (kW) model requires a 240-volt (V) supply and three 50 amp (A) breakers. There are many Stiebel Eltron models in the Tempra range, offering high-quality solutions for installations of various types and sizes. The unit’s safety is recognized by UL and CSA certification.

Get the Stiebel Eltron electric tankless water heater at Amazon or The Home Depot.

Runner-Up

EcoSmart ECOS 27 Electric Tankless Water Heater

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Product Specs 

• Model: ECOS 27
• Maximum temperature: 140 degrees Fahrenheit
• Maximum flow rate: 6.6 GPM
• Efficiency rating: 94 percent

What We Like

• Auto-modulation features gives this water heater a high efficiency rating
• Minimal activation requirement of 0.3 GPM does not require full water pressure for heat
• Can serve larger homes with high maximum flow rate of 6.6 GPM

What We Don’t Like

• Some complaints about low build quality resulting in water leaking into the heat exchanger

The EcoSmart ECOS 27 electric tankless water heater is a compact unit that still offers competitive performance with a maximum of 6.6 GPM. It also has a minimal activation requirement of 0.3 GPM, so users don’t have to turn faucets on full power to get hot water. A less responsive electric water heater would waste water and electricity used for heating, but this one provides optimal control.

Like many other leading devices, this model uses flow modulation when heating water. This leads to optimal energy conservation while ensuring that changes in supply temperature or pressure have no impact on hot-water output. The maximum achievable temperature is 140 degrees Fahrenheit and its energy efficiency is 94 percent.

Running at 27kW, the EcoSmart ECOS 27 requires a 240V power supply and three 40A breakers. The device is both UL and CSA certified for safety.

Get the EcoSmart ECOS 27 electric tankless water heater at Amazon, Ace Hardware, or The Home Depot.

Best Bang for the Buck

Thermomate 18kW Tankless Electric Water Heater

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Product Specs 

• Model: 18kW
• Maximum temperature: 140 degrees Fahrenheit
• Maximum flow rate: 4.5 GPM
• Efficiency rating: 99.8 percent

What We Like

• Budget-friendly unit provides enough power for up to 3 applications
• Equipped with low-maintenance heating elements that are less likely to corrode than some
• Digital thermostat and dual controls make it easy to adjust temperatures

What We Don’t Like

• Modest flow rate might not meet demands of multibath homes

The budget-friendly 18 kW Thermomate tankless water heater is an economical solution designed to provide virtually instant hot water for up to three different applications. Despite the low cost, there’s still a digital thermostat adjustable in single-degree increments and self-modulated control for stable temperature output, plus maximum energy savings.

The heating elements run adjacent to the water supply rather than being immersed, reducing scale and corrosion for longer life. There is overheating protection, dry-heat protection in the event of interruption to the water supply, and the unit is Electric Testing Laboratories (ETL) certified for safety.

The Thermomate range also offers low-cost electric tankless water heaters at 11kW and 27kW, providing money-saving solutions for a variety of hot-water demands. This 18kW unit requires 240V and two 40A breakers. The model has a high 99.8 efficiency rating.

Get the Thermomate electric tankless water heater at Amazon or Thermomate.

Best for Smaller Homes

EcoSmart ECO 11 Electric Tankless Water Heater

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Product Specs 

• Model: ECO 11
• Maximum temperature: 140 degrees Fahrenheit
• Maximum flow rate: 3.1 GPM
• Efficiency rating: 99.8 percent

What We Like

• Affordable unit that saves up to 50 percent on annual hot-water costs
• Highly efficient model provides simultaneous heat for a shower and low-flow sink
• Self-modulating technology provides stable temperature output while saving energy

What We Don’t Like

• Some complaints about warranty claims

Those who live in compact modern homes will want to take a close look at the EcoSmart ECO 11. Rated for a maximum of 3.1 GPM, this affordable unit can provide constant hot water for a shower and low-flow faucet simultaneously. It is one of few electric tankless water heaters that uses the accurate Uniform Energy Factor (UEF) standard, with outstanding efficiency of 99.8 percent.

As with all the models in the EcoSmart range, the ECO 11 has self-modulating technology. The DOE estimates it saves around 50 percent on hot-water costs per year. The digital display provides temperature-control adjustment in 1-degree steps, anywhere from 80 to 140 degrees Fahrenheit. The EcoSmart ECO 11 is an 11.8kW device requiring 220V and a single 60A breaker.

Get the EcoSmart ECO 11 electric tankless water heater at Amazon or The Home Depot.

Best For Large Homes

Rheem RETEX-36 Performance Tankless Water Heater

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Product Specs 

• Model: Performance RETEX-36
• Maximum temperature: 140 degrees Fahrenheit
• Maximum flow rate: 8 GPM
• Efficiency rating: 99.8 percent

What We Like

• Has a high flow rate of 8 GPM for serving multiple faucets and showers
• Can reach a high maximum temperature of 140 degrees Fahrenheit
• Self-modulates based on usage patterns to maximize energy savings

What We Don’t Like

• Takes up a lot of space in the electrical box with 4 double pole breakers

With its high flow rate and max temperature, this 36kW model from one of the top brands in water heaters is a good option for larger homes. The Rheem tankless water heater can serve up to four showers and one faucet. Its thermostat has a top range of 140 degrees Fahrenheit and is adjustable in 1-degree increments from 80 to 140 degrees Fahrenheit. Temperature changes are easy to make thanks to a digital display and simple dial controls.

With its self-modulating technology, this Rheem tankless water heater will adjust the amount of energy it uses based on the home’s water consumption, helping to further save money. The Rheem 8 GPM tankless water heater takes up a fair amount of space in the electrical panel. With its high 36kW output, it requires a 240V power supply and uses four 40A double pole breakers.

Get the Rheem RETEX-36 electric tankless water heater at Amazon or The Home Depot.

Most Versatile

Airthereal 27kW Electric Tankless Water Heater

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Product Specs 

• Model: 27kW
• Maximum temperature: 114 degrees Fahrenheit
• Maximum flow rate: 5.5 GPM
• Efficiency rating: N/A

What We Like

• Comes in a broad range of sizes to suit homes both large and small
• Digital interface makes it easy to set the temperature and diagnose problems
• One of the more affordably priced tankless water heaters

What We Don’t Like

• Some customers complain that it doesn’t get water hot enough

Shoppers won’t have a problem finding that just-right-size tankless water heater for their home with the Airthereal series. That’s because it comes in five different sizes, ranging from 8kW to 27kW. It’s rated for a flow rate of between 2.5 GPM to 5.5 GPM, depending on the size of the unit, making it an option for homes ranging in size from a small condo to a 4-bedroom house.

A digital display allows the user to view the current temperature settings, quickly make temperature changes, and toggle between heating and standby mode. The display also shows error codes, making it easier to diagnose malfunctions. The 27kW Airthereal tankless water heater requires a 240V connection and three 40A circuit breakers, but the smaller 8kW needs only one 40A breaker.

Get the Airthereal electric tankless water heater at Amazon. 

Best Point-of-Use Unit

Ecotouch Tankless Water Heater

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Product Specs 

• Model: 5.5kW
• Maximum temperature: 116 degrees Fahrenheit
• Maximum flow rate: 1.5 GPM
• Efficiency rating: 98 percent

What We Like

• Compact size is ideal for installation in s