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10 Best Whole House Tankless Electric Hot Water Heaters 2025 in the United States

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Our technology thoroughly searches through the online shopping world, reviewing hundreds of sites. We then process and analyze this information, updating in real-time to bring you the latest top-rated products. This way, you always get the best and most current options available.

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Our Top Picks

#1

Winner

Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White, 20.2

Rating
9.8
Chosen by1,435
Flow Rate (GPM)
Temperature Rise
Power (kW)

Most important from
2065 reviews

Flow Rate (GPM)
The unit's performance has exceeded expectations in terms of convenience and efficiency, providing continuous hot water even when running two showers simultaneously.
Temperature Rise
Precise temperature control ensures you get the desired hot water without any fuss.
Power (kW)
The unit operates without consuming power when not in use, and provides instant hot water upon return after a long absence.
Energy Efficiency
The heater uses only the necessary hot water, making it eco-friendly and cost-effective.
Installation Requirements
Its space-saving design and minimal noise are standout features, making it ideal for installation near living spaces.

The Stiebel Eltron Tankless Water Heater – Tempra 24 Plus is a robust option for homeowners looking for an electric solution to efficiently provide hot water on demand. With a flow rate of 4.0 GPM and the ability to maintain a temperature rise of up to 140°F, it can comfortably supply hot water for multiple outlets simultaneously, making it suitable for larger households. Its eco-friendly design incorporates advanced flow control technology, which adjusts the water flow to maintain a consistent temperature, ensuring that you won’t be left with a cold shower.

One of the standout features is its space-saving design. The unit is compact and does not require venting, which allows for flexible installation options. The digital display and preset temperature buttons make operation simple, even for those who may not be tech-savvy. Energy efficiency is a strong point, too, as the heater saves power through auto-modulation, and a savings monitor shows how much you’re saving on energy costs.

However, there are a few considerations to keep in mind. The Tempra 24 Plus requires a minimum electric service of 150 A, which may necessitate upgrades to your home's electrical system if it doesn't meet this requirement. Additionally, while the compact size is beneficial, it may not be suitable for very high-demand scenarios where multiple fixtures are used simultaneously at peak demand times. The warranty coverage is quite favorable, offering a 7-year leakage warranty and a 3-year parts warranty, which is reassuring for potential buyers. The Stiebel Eltron Tempra 24 Plus is a solid choice for those seeking an efficient and reliable tankless hot water heater that can provide endless hot water without the bulk of traditional systems.

Rating
9.8
Chosen by1,435
Flow Rate (GPM)
Temperature Rise
Power (kW)

Most important from
2065 reviews

Flow Rate (GPM)
The unit's performance has exceeded expectations in terms of convenience and efficiency, providing continuous hot water even when running two showers simultaneously.
Temperature Rise
Precise temperature control ensures you get the desired hot water without any fuss.
Power (kW)
The unit operates without consuming power when not in use, and provides instant hot water upon return after a long absence.
Energy Efficiency
The heater uses only the necessary hot water, making it eco-friendly and cost-effective.
Installation Requirements
Its space-saving design and minimal noise are standout features, making it ideal for installation near living spaces.
#2

Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray

Rating
9.6
Power (kW)
Energy Efficiency
Installation Requirements

Most important from
787 reviews

Power (kW)
Despite the high power demand, the unit remains off most of the time, only using energy when needed.
Energy Efficiency
The Rheem RTEX-24 is compact yet powerful, heating water quickly and efficiently.
Installation Requirements
The unit is easy to install and works exactly as intended, providing a hassle-free experience.

The Rheem RTEX-24 is a solid choice for those looking to upgrade to a tankless electric hot water heater for their home. With a flow rate of up to 5.9 gallons per minute (GPM), it can efficiently provide hot water for multiple outlets simultaneously, making it great for medium-sized households. Its self-modulating power control ensures that you get just the right amount of energy needed for heating water, which contributes to its impressive energy efficiency rating of 99.8%. This means you can enjoy consistent, on-demand hot water without worrying too much about energy consumption.

One notable feature is its ON/OFF dial control paired with an adjustable digital temperature display, making it user-friendly. Installation is straightforward, as it is designed for wall mounting and comes with necessary fittings, although professional help might still be recommended for optimal setup. The compact size of the unit (17.63” W x 18.25” H) allows it to fit conveniently in smaller spaces.

While the flow rate is decent, it may struggle to meet the hot water demands of larger households with simultaneous usage in multiple bathrooms or kitchens. The 24 kW power requirement also means that proper electrical infrastructure is necessary; homes must have the right voltage and amperage to support this unit. Additionally, while the warranty coverage is decent, some users may prefer a longer guarantee for peace of mind.

Rating
9.6
Power (kW)
Energy Efficiency
Installation Requirements

Most important from
787 reviews

Power (kW)
Despite the high power demand, the unit remains off most of the time, only using energy when needed.
Energy Efficiency
The Rheem RTEX-24 is compact yet powerful, heating water quickly and efficiently.
Installation Requirements
The unit is easy to install and works exactly as intended, providing a hassle-free experience.
#3

EcoSmart ECO 27 Tankless Water Heater, Electric, 27-kW - Quantity 1, 17 x 17 x 3.5

Rating
9.3
Flow Rate (GPM)
Power (kW)
Energy Efficiency

Most important from
2995 reviews

Flow Rate (GPM)
The EcoSmart ECO 27 provides unlimited hot water, even with multiple fixtures running simultaneously.
Power (kW)
Some users have successfully installed the unit on a subpanel with less than the recommended amperage without issues.
Energy Efficiency
Significant savings on energy bills have been noted, with the product paying for itself in just a few years.
Installation Requirements
Installation can be straightforward for those with electrical and plumbing experience, though professional installation is recommended to maintain the warranty.

The EcoSmart ECO 27 Tankless Water Heater is a solid choice for homeowners seeking a reliable and efficient hot water solution. One of its major strengths is its endless hot water supply, which means you won't run out even during peak usage times. It offers a flow rate between 2.7 to 6.5 gallons per minute depending on the inlet water temperature, making it suitable for whole-house applications. The unit is compact, taking up significantly less space than traditional tank heaters, allowing for flexible installation options.

Energy efficiency is another highlight, as it operates at 99% thermal energy efficiency. This means it heats water only when needed, which can lead to savings of up to 50% on water heating costs, according to the Department of Energy. The digital temperature control with increments of 1 degree offers users precise control over water temperature.

There are some considerations to keep in mind. The ECO 27 requires a significant electrical setup, needing three 40 AMP double pole breakers and a recommended 200 Amp electrical panel. This might involve additional upfront costs for installation if your home isn't already equipped for it. Additionally, the warranty, while limited lifetime on components, does not cover labor costs or incidental damages, which could be a drawback for some users. This heater is particularly suitable for families or households that require consistent hot water without the bulk of traditional storage heaters, but may not be ideal for those with limited electrical infrastructure.

Rating
9.3
Flow Rate (GPM)
Power (kW)
Energy Efficiency

Most important from
2995 reviews

Flow Rate (GPM)
The EcoSmart ECO 27 provides unlimited hot water, even with multiple fixtures running simultaneously.
Power (kW)
Some users have successfully installed the unit on a subpanel with less than the recommended amperage without issues.
Energy Efficiency
Significant savings on energy bills have been noted, with the product paying for itself in just a few years.
Installation Requirements
Installation can be straightforward for those with electrical and plumbing experience, though professional installation is recommended to maintain the warranty.

Buying Guide for the Best Whole House Tankless Electric Hot Water Heaters

Choosing the right whole-house tankless electric hot water heater can significantly impact your home's comfort and energy efficiency. These systems provide hot water on demand, which means you won't run out of hot water and you can save on energy costs since they don't maintain a reservoir of hot water. However, selecting the right model involves understanding several key specifications to ensure it meets your household's needs. Here’s a guide to help you navigate through the essential specs and make an informed decision.
Flow Rate (GPM)Flow rate, measured in gallons per minute (GPM), indicates how much hot water the unit can deliver at a time. This is crucial because it determines whether the heater can handle multiple hot water demands simultaneously, such as running a shower and a dishwasher. For smaller households with fewer simultaneous hot water needs, a lower GPM (around 3-5 GPM) may suffice. Larger households or those with higher hot water demands should look for units with higher GPM (6-10+ GPM). Assess your household's peak hot water usage to choose the right flow rate.
Temperature RiseTemperature rise refers to the increase in water temperature the unit can achieve. This is important because it affects how hot the water will be when it reaches your taps. The required temperature rise depends on your incoming water temperature and your desired output temperature. For instance, if your incoming water is 50°F and you want it at 120°F, you need a unit that can handle a 70°F rise. Colder climates may require units with higher temperature rise capabilities. Consider your local water temperature and your preferred hot water temperature to determine the necessary temperature rise.
Power (kW)The power rating, measured in kilowatts (kW), indicates the electrical power the unit uses to heat water. Higher kW ratings generally mean the unit can heat water more quickly and handle higher flow rates. Units typically range from 18 kW to 36 kW or more. Smaller households with lower hot water demands can opt for units on the lower end of the spectrum, while larger households or those with higher demands should consider higher kW ratings. Ensure your home's electrical system can support the power requirements of the unit you choose.
Energy EfficiencyEnergy efficiency measures how effectively the unit converts electrical energy into hot water, often expressed as a percentage. Higher efficiency means lower energy waste and reduced operating costs. Look for units with efficiency ratings of 90% or higher for the best performance. Consider your long-term energy savings and environmental impact when evaluating efficiency.
Installation RequirementsInstallation requirements include the electrical and space considerations necessary for setting up the unit. Tankless electric water heaters often require specific voltage and amperage, as well as adequate space for ventilation and maintenance. Ensure your home’s electrical system can accommodate the unit’s requirements, and that you have enough space for proper installation. Consulting with a professional installer can help you understand these needs and avoid potential issues.
WarrantyThe warranty provides an indication of the unit’s reliability and the manufacturer’s confidence in their product. Longer warranties can offer peace of mind and protection against defects or failures. Warranties typically range from 5 to 15 years. Consider how long you plan to stay in your home and your comfort level with potential repair costs when evaluating warranty options.

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