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10 Best high efficiency tankless electric hot water heaters 2025 in the United States

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Our Top Picks

#1

Winner

Ranein Electric Tankless Water Heater, 18kW 240V on Demand Instant Endless Water Heater with LED Temperature Display for Residential Whole House Shower, Space Saving

Rating
10.0
Chosen by1,209
Flow Rate
Temperature Rise
Energy Efficiency

Most important from
113 reviews

Flow Rate
This water heater delivers plenty of hot water consistently, perfectly meeting the needs of small to medium households.
Temperature Rise
The digital temperature display and easy-to-adjust controls add great convenience and precision.
Energy Efficiency
Energy savings are noticeable, reducing electricity costs compared to traditional tank heaters.
Size and Installation
Installation is straightforward and quick, making it accessible for those with some DIY experience or professional help.

The Ranein 18kW Tankless Electric Water Heater offers strong performance for small to medium residential needs, particularly suitable for 2-3 usage points like showers or sinks. Its flow rate of up to 4.3 gallons per minute means it can provide a steady stream of hot water without delays, which is great if you want endless hot water on demand. The unit is compact, with dimensions around 14 by 19 inches, making it easy to install in tight spaces or wall-mounted. One of its biggest strengths is energy efficiency; it claims up to 99% thermal efficiency and can save about 60% on heating costs compared to traditional tank heaters, since it only heats water when needed. Temperature control is user-friendly with a knob and clear LED display, allowing adjustment in small 1°F steps, up to 131°F. This makes it flexible for family comfort and safety. On the safety side, it includes protections against leaks and overheating, which adds peace of mind.

However, it requires a 240V power supply and two 40-amp circuit breakers, so your home's electrical system must support this load, which could require professional installation or upgrades. While it handles moderate water needs well, the flow rate might be limiting for larger households with multiple simultaneous demands. The warranty and customer reviews indicate decent reliability, but its performance depends on correct sizing for your household. If you want a space-saving, efficient, and easy-to-use tankless water heater for a small to medium home setup, this model presents a solid choice.

Rating
10.0
Chosen by1,209
Flow Rate
Temperature Rise
Energy Efficiency

Most important from
113 reviews

Flow Rate
This water heater delivers plenty of hot water consistently, perfectly meeting the needs of small to medium households.
Temperature Rise
The digital temperature display and easy-to-adjust controls add great convenience and precision.
Energy Efficiency
Energy savings are noticeable, reducing electricity costs compared to traditional tank heaters.
Size and Installation
Installation is straightforward and quick, making it accessible for those with some DIY experience or professional help.
#2

Stiebel Eltron Tankless Heater – Tempra 36 Plus – Electric, On Demand Hot Water, Eco, White

Rating
10.0
Flow Rate
Temperature Rise
Energy Efficiency

Most important from
2103 reviews

Flow Rate
Delivers a continuous flow of hot water with no interruptions, even when running two showers simultaneously.
Temperature Rise
Advanced temperature control allows for precise settings and presets, making it easy to achieve the desired water temperature without guesswork.
Energy Efficiency
Energy-efficient performance that only uses power when hot water is needed, contributing to noticeable cost savings on utility bills.
Power Requirements
Requires a dedicated electrical setup, including multiple circuit breakers and possibly a subpanel, which may necessitate professional installation and electrical upgrades.
Size and Installation
Impressively quiet operation and a compact, space-saving design that fits conveniently near living spaces.
Warranty
Robust German engineering with a solid build quality ensures long-term reliability and quiet operation.

The Stiebel Eltron Tempra 36 Plus is a high-powered tankless electric water heater designed to deliver continuous hot water on demand. It operates at 27,000 watts with a maximum flow rate of 1.5 gallons per minute, which is suitable for smaller households or point-of-use setups but might be limiting if you need simultaneous hot water at multiple fixtures. Its advanced flow control and self-modulation technology help save energy by adjusting power use based on demand, making it a strong choice if you're looking to reduce utility bills.

The digital LED display allows for precise temperature control, which adds convenience and helps maintain consistent water temperature. Installation is straightforward with a floor mounting method, and the unit is relatively compact at about 17 by 14.5 inches, so it won’t take up much space. However, it requires a 208-volt power supply, which might need electrical upgrades in some homes. The product is well-reviewed for reliability and efficiency.

If you want an energy-efficient electric tankless heater for a smaller capacity setting and don’t mind the electrical requirements, the Tempra 36 Plus represents a solid, dependable option.

Rating
10.0
Flow Rate
Temperature Rise
Energy Efficiency

Most important from
2103 reviews

Flow Rate
Delivers a continuous flow of hot water with no interruptions, even when running two showers simultaneously.
Temperature Rise
Advanced temperature control allows for precise settings and presets, making it easy to achieve the desired water temperature without guesswork.
Energy Efficiency
Energy-efficient performance that only uses power when hot water is needed, contributing to noticeable cost savings on utility bills.
Power Requirements
Requires a dedicated electrical setup, including multiple circuit breakers and possibly a subpanel, which may necessitate professional installation and electrical upgrades.
Size and Installation
Impressively quiet operation and a compact, space-saving design that fits conveniently near living spaces.
Warranty
Robust German engineering with a solid build quality ensures long-term reliability and quiet operation.
#3

Stiebel Eltron 239223 Tankless Water Heater – Tempra 29 Plus – Electric, On Demand Hot Water, Eco, White, 23

Rating
10.0
Flow Rate
Temperature Rise
Energy Efficiency

Most important from
2103 reviews

Flow Rate
Delivers a continuous flow of hot water even when running multiple showers simultaneously without interruption.
Temperature Rise
Provides precise and easy temperature control with memory presets, allowing for perfect hot water settings every time.
Energy Efficiency
Uses energy only when hot water is needed, ensuring eco-friendly and cost-effective operation.
Power Requirements
Installation may require significant electrical upgrades, including multiple breakers and a dedicated sub-panel, due to its high power demands.
Size and Installation
Its compact, space-saving design frees up valuable room and fits flexibly in many home layouts.

The Stiebel Eltron Tempra 29 Plus is a powerful, high-efficiency tankless electric water heater designed to provide continuous hot water on demand. It delivers up to 3 gallons per minute, which is suitable for a household with moderate hot water needs, like running one or two showers plus a sink at the same time. Its compact size (about 17 by 15 inches) helps save space and the sleek design means no venting is required, making installation flexible for many homes.

The unit has a strong 28.8 kW power output, meaning it can heat water quickly with a notable temperature rise, which is great if you live in colder climates and need a consistent hot water supply. An LED display and two temperature memory presets make it easy to set and save your preferred water temperatures. On the energy side, it’s very efficient, so it won’t waste electricity heating water when you don’t need it. However, this heater requires a substantial electrical setup: a dedicated 240-volt or 208-volt hard-wired connection, 3 separate 40-amp breakers, and at least a 200-amp main service panel. This means you might need professional electrical upgrades, which can add to installation cost and complexity.

The unit is relatively lightweight at 24 pounds and mounts on the wall, freeing up floor space. If you have a large household or very high hot water demands, you might find the 3 GPM flow limiting, but for many, it balances power, efficiency, and convenience effectively.

Rating
10.0
Flow Rate
Temperature Rise
Energy Efficiency

Most important from
2103 reviews

Flow Rate
Delivers a continuous flow of hot water even when running multiple showers simultaneously without interruption.
Temperature Rise
Provides precise and easy temperature control with memory presets, allowing for perfect hot water settings every time.
Energy Efficiency
Uses energy only when hot water is needed, ensuring eco-friendly and cost-effective operation.
Power Requirements
Installation may require significant electrical upgrades, including multiple breakers and a dedicated sub-panel, due to its high power demands.
Size and Installation
Its compact, space-saving design frees up valuable room and fits flexibly in many home layouts.

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.

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