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10 Best high efficiency tankless electric hot water heaters 2025 in the United States
#1
Winner
Stiebel Eltron Tankless Water Heater - Tempra 29 Trend – Electric, On Demand Hot Water, Eco, White
The Stiebel Eltron Tempra 29 Trend is a standout in the category of high-efficiency tankless electric hot water heaters, perfect for homeowners seeking an endless supply of hot water. Its continuous flow feature ensures that hot showers are never interrupted, which is a major plus for families or anyone who frequently uses hot water. With a power output of 28.8 kW, it quickly heats water between temperatures of 68°F and 140°F, catering well to varying needs.
Rating
9.9
Chosen by1,258
Flow Rate
Temperature Rise
Energy Efficiency
Most important from
2075 reviews
#2
Rheem 18kW 240V Tankless Electric Water Heater, Gray
The Rheem 18kW 240V Tankless Electric Water Heater is a high-efficiency water heating solution with several notable strengths. Featuring an external digital thermostatic control with an LED display, it allows precise temperature management with a +/- 1 degree accuracy. This level of control is beneficial for maintaining consistent water temperature. The self-modulation feature is another significant advantage, as it adjusts power usage based on hot water demand, enhancing energy efficiency and potentially lowering electricity costs.
Rating
9.8
Temperature Rise
Size and Installation
Most important from
1959 reviews
#3
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
The Rheem RTEX-24 24kW 240V Electric Tankless Water Heater offers an impressive flow rate of up to 5.9 gallons per minute (GPM), which is quite strong for most household needs. Its self-modulating power control ensures efficient energy use by adjusting power based on hot water demand, contributing to its notable 99.8% energy efficiency.
Rating
9.5
Flow Rate
Temperature Rise
Energy Efficiency
Most important from
793 reviews
Top 10 Best high efficiency tankless electric hot water heaters 2025 in the United States
#1
Winner
9.9 score
Stiebel Eltron Tankless Water Heater - Tempra 29 Trend – Electric, On Demand Hot Water, Eco, White
Stiebel Eltron Tankless Water Heater - Tempra 29 Trend – Electric, On Demand Hot Water, Eco, White
Flow Rate: continuous flow
Temperature Rise: 68°F to 140°F
Energy Efficiency: auto modulation
Power Requirements: 28.8 kW, 200 A
Size and Installation: 16.63"W x 14.5"H
Warranty: 7 years leakage, 3 years parts
Chosen by 1258 this week
Rheem 18kW 240V Tankless Electric Water Heater, Gray
Rheem 18kW 240V Tankless Electric Water Heater, Gray
Flow Rate: 4.4 gallons per minute
Energy Efficiency: self-modulation feature
Power Requirements: 18,000 watts at 240 volts
Size and Installation: 14.5"W x 18.25"H, 3/4 inch NPT
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
Flow Rate: 5.9 GPM
Energy Efficiency: 99.8%
Power Requirements: 24kW, 240V
Size and Installation: 17.63”W x 18.25”H x 3.5”D
EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
Flow Rate: 1.3 to 3.1 gallons/min
Energy Efficiency: 99%
Power Requirements: 13KW, 240V, 54A
Size and Installation: 8"W x 11.5"H x 3.75"D
Warranty: Lifetime on electronics, exchanger, element
Rheem 11kW 240V Tankless Electric Water Heater
Rheem 11kW 240V Tankless Electric Water Heater
Flow Rate: 2.68 GPM
Energy Efficiency: self-modulating control
Power Requirements: 240V, 11kW
Size and Installation: 8.25"W x 12.63"H, Wall Mount
Related Products
Rheem 8kW 240V Tankless Electric Water Heater
Rheem 8kW 240V Tankless Electric Water Heater
Flow Rate: 1.95 GPM
Energy Efficiency: self-modulating control
Power Requirements: 240V
Size and Installation: 8.25"W x 12.63"H, Wall Mount
EcoSmart ECO 27 Tankless Water Heater, Electric, 27-kW - Quantity 1, 17 x 17 x 3.5
EcoSmart ECO 27 Tankless Water Heater, Electric, 27-kW - Quantity 1, 17 x 17 x 3.5
Flow Rate: 2.7 to 6.5 GPM
Energy Efficiency: 99%
Power Requirements: Three 40 Amp double pole breakers
Size and Installation: 17 x 17 x 3.5 inches
Warranty: Limited Lifetime Warranty
Electric Tankless Hot Water Heater, ECOTOUCH 18kW on Demand Instant Water Heater 240V, ETL Certificated Self-Modulation Point of Use Hot Water Heater Whole House ECO180B Black
Electric Tankless Hot Water Heater, ECOTOUCH 18kW on Demand Instant Water Heater 240V, ETL Certificated Self-Modulation Point of Use Hot Water Heater Whole House ECO180B Black
Flow Rate: 1.8 Gallons Per Minute
Temperature Rise: 120°F or higher
Energy Efficiency: 98%
Power Requirements: 240V, 2x40AMP breakers
Size and Installation: 12.22"W x 17.25"H, Wall-Mounted
Warranty: One year
Ecosmart ECO 24 24 KW at 240-Volt Electric Tankless Water Heater with Patented Self Modulating Technology, 17 x 17 x 3.5
Ecosmart ECO 24 24 KW at 240-Volt Electric Tankless Water Heater with Patented Self Modulating Technology, 17 x 17 x 3.5
Flow Rate: 5.8 Gallons Per Minute
Temperature Rise: up to 130°F
Energy Efficiency: 99.8%
Power Requirements: 100-amp, 240V, 24000W
Size and Installation: 17 x 17 x 3.5 inches
Warranty: Lifetime on electronics, exchanger, element
#10
7.6 score
Rheem RTEX-36 36kW Electric Tankless Water Heater 240V Ext Adj Temp Ctrl Bot 3/4 in. Npt Con
Rheem RTEX-36 36kW Electric Tankless Water Heater 240V Ext Adj Temp Ctrl Bot 3/4 in. Npt Con
Flow Rate: 6 Gallons Per Minute
Energy Efficiency: Energy efficient
Power Requirements: 240 Volts, 36 KW
Size and Installation: Compact and stylish
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Buying Guide for the Best high efficiency tankless electric hot water heaters
Choosing the right high-efficiency tankless electric hot water heater can significantly impact your home's energy consumption and ensure you have a reliable supply of hot water. These heaters are known for their energy efficiency and ability to provide hot water on demand, without the need for a storage tank. When selecting a model, it's important to consider several key specifications to ensure you get the best fit for your needs. Understanding these specs will help you make an informed decision and find a heater that meets your household's hot water demands efficiently.Flow RateFlow rate, measured in gallons per minute (GPM), indicates how much hot water the unit can produce at a given time. This spec is crucial because it determines whether the heater can meet your household's hot water needs. For example, a flow rate of 2-3 GPM is suitable for small households or single-point applications like a shower. A flow rate of 4-6 GPM can handle multiple fixtures simultaneously, making it ideal for medium-sized homes. Larger households with high hot water demands should look for units with a flow rate of 7 GPM or higher. Assess your household's hot water usage to determine the appropriate flow rate.
Temperature RiseTemperature rise refers to the increase in water temperature as it passes through the heater. This spec is important because it affects how hot the water will be when it reaches your tap. The temperature rise needed depends on the incoming water temperature and your desired hot water temperature. For instance, if your incoming water is 50°F and you want it to be 120°F, you need a temperature rise of 70°F. Higher temperature rise capabilities are necessary for colder climates or if you require very hot water. Consider your local water temperature and your hot water preferences when evaluating this spec.
Energy EfficiencyEnergy efficiency, often expressed as a percentage, indicates how effectively the heater converts electrical energy into hot water. Higher efficiency means less energy waste and lower utility bills. Look for units with an energy efficiency rating of 90% or higher for optimal performance. Some models may also have an Energy Star certification, which signifies they meet strict energy efficiency guidelines. If reducing energy consumption and saving on electricity costs are priorities for you, prioritize models with higher efficiency ratings.
Power RequirementsPower requirements refer to the electrical specifications needed to operate the heater, including voltage and amperage. This spec is important because it determines whether your home's electrical system can support the unit. Most tankless electric water heaters require a 240-volt connection and varying amperage levels, typically between 30 to 120 amps. Ensure your home's electrical panel can accommodate the heater's power requirements, and consider consulting an electrician if you're unsure. Choose a model that matches your home's electrical capacity to avoid potential installation issues.
Size and InstallationThe size and installation requirements of the heater are important for ensuring it fits in your designated space and can be installed properly. Tankless electric water heaters are generally compact, but sizes can vary. Measure the available space and compare it to the unit's dimensions to ensure a proper fit. Additionally, consider the installation process, which may involve electrical work and plumbing adjustments. Some models are easier to install than others, so if you prefer a straightforward installation, look for units with simpler requirements. Assess your space and installation capabilities to choose a model that fits your needs.
WarrantyThe warranty provided by the manufacturer is an important consideration as it offers protection and peace of mind. Warranties can vary in length and coverage, typically ranging from 5 to 10 years for parts and sometimes including labor. A longer warranty period indicates the manufacturer's confidence in the product's durability and reliability. When comparing models, consider the warranty terms and what is covered. Opt for a unit with a comprehensive warranty to ensure you are protected against potential defects and issues.