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10 Best Outdoor 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 29 Trend – Electric, On Demand Hot Water, Eco, White

Rating
9.8
Chosen by1,399
Flow Rate (GPM)
Power (kW)
Temperature Rise

Most important from
2089 reviews

Flow Rate (GPM)
The unit's performance has exceeded expectations in terms of convenience and efficiency, providing a continuous flow of hot water even when running two showers simultaneously.
Power (kW)
The unit consumes no power when not in use, making it highly efficient.
Temperature Rise
The temperature control is precise, ensuring you get the hot water you desire without any fuss.
Energy Efficiency
It uses only the necessary amount of hot water, which is eco-friendly and cost-effective.
Installation Requirements
The heater is impressively quiet and its space-saving design is a game-changer, making it ideal for installation near living spaces.
Durability and Warranty
The product is well-constructed, robust, and operates with absolute silence, making it easy to install and use.

The Stiebel Eltron Tempra 29 Trend is a solid choice for those seeking a reliable and efficient tankless electric hot water heater for their home. One of its main strengths is its continuous flow feature, which ensures that you never run out of hot water, making it ideal for families or households with high hot water demands. With a maximum flow rate of 9.5 gallons per minute, it can easily handle multiple tasks simultaneously, like showering and washing dishes.

Its energy efficiency is another highlight. The auto-modulation feature means the heater adjusts its power output based on the demand, saving energy when hot water is not being used. This eco-friendly design is a great benefit for those looking to minimize their environmental impact and utility bills.

In terms of installation, the compact design requires no venting and can be mounted on the wall, saving valuable space. However, it does require a minimum electrical service of 200 A, which might necessitate an upgrade for some households. The Tempra 29 Trend operates silently, enhancing user experience, especially in quiet home settings. The digital temperature display is easy to read, adding convenience when adjusting settings.

Rating
9.8
Chosen by1,399
Flow Rate (GPM)
Power (kW)
Temperature Rise

Most important from
2089 reviews

Flow Rate (GPM)
The unit's performance has exceeded expectations in terms of convenience and efficiency, providing a continuous flow of hot water even when running two showers simultaneously.
Power (kW)
The unit consumes no power when not in use, making it highly efficient.
Temperature Rise
The temperature control is precise, ensuring you get the hot water you desire without any fuss.
Energy Efficiency
It uses only the necessary amount of hot water, which is eco-friendly and cost-effective.
Installation Requirements
The heater is impressively quiet and its space-saving design is a game-changer, making it ideal for installation near living spaces.
Durability and Warranty
The product is well-constructed, robust, and operates with absolute silence, making it easy to install and use.
#2

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

Rating
9.6
Flow Rate (GPM)
Temperature Rise
Installation Requirements

Most important from
2089 reviews

Flow Rate (GPM)
Continuous flow of hot water, even when running two showers simultaneously.
Temperature Rise
Accurate temperature control with presets for specific needs like filling a soaking tub.
Installation Requirements
Installation flexibility, no flue required, and quick hot water where it's needed.
Durability and Warranty
Robust construction and easy to install and operate, justifying its higher price.

The Stiebel Eltron Tempra 36 Trend offers a practical solution for those seeking a tankless electric water heater that provides on-demand hot water. It ensures a continuous flow, meaning you won't run out of hot water during long showers, which is a significant advantage for families or households with higher water demands. With a powerful 36kW capacity, it can support a temperature rise from 68° to 140°F, making it suitable for various climates and use cases. However, the flow rate is on the lower side at 0.77 GPM, which might not suffice if multiple water outlets are used simultaneously.

This model is energy efficient, benefiting from an eco-friendly design and auto-modulation to conserve energy when not in use. Its compact size makes it a space-saving option that can be wall-mounted without requiring venting, simplifying installation. However, it demands a substantial electrical service of 300A, which might necessitate an electrical system upgrade in some homes.

The Tempra 36 Trend operates silently, and its digital temperature display is user-friendly, enhancing its appeal for home use. Constructed with a solid copper heating system, it promises durability, and the included warranties—a 7-year leakage and 3-year parts guarantee—further attest to its reliability. Weighing 22.5 pounds, its installation is relatively straightforward, although professional installation is recommended to deal with its high power requirements. While it ranks well in customer satisfaction, as seen in its 4.5-star rating, potential buyers should consider their home’s electrical capacity and water demand requirements before purchasing. This heater is particularly well-suited for single-family homes looking for an eco-friendly, space-efficient hot water solution.

Rating
9.6
Flow Rate (GPM)
Temperature Rise
Installation Requirements

Most important from
2089 reviews

Flow Rate (GPM)
Continuous flow of hot water, even when running two showers simultaneously.
Temperature Rise
Accurate temperature control with presets for specific needs like filling a soaking tub.
Installation Requirements
Installation flexibility, no flue required, and quick hot water where it's needed.
Durability and Warranty
Robust construction and easy to install and operate, justifying its higher price.
#3

Rheem 18kW 240V Tankless Electric Water Heater, Gray

Rating
9.5
Power (kW)
Temperature Rise
Installation Requirements

Most important from
1969 reviews

Power (kW)
Was cheaper than Home Depot and pulls about 8kW upon use.
Temperature Rise
You may feel the need to set the temp to 145°F, but you don't unless using multiple hot water devices simultaneously.
Installation Requirements
Installed it in a tiny house and it works wonderfully.

The Rheem 18kW 240V Tankless Electric Water Heater is a solid choice for those looking for a reliable hot water solution, especially in outdoor settings. With a maximum flow rate of 4.4 gallons per minute, it’s well-suited for moderate demand, making it ideal for small to medium-sized households or outdoor applications where hot water is needed intermittently.

One of the standout features is its external digital thermostatic control with a clear LED display, allowing for precise temperature adjustments. The advanced self-modulation technology helps manage energy use effectively, which can lead to savings on electricity bills. Its impressive energy efficiency rating of 99.8% means you’re getting almost all the energy converted into hot water, which is great for eco-conscious users.

The installation process is user-friendly, thanks to the bottom 3/4 inch NPT water connections and the wall-mount design, making it a practical option for those who might consider a DIY installation. The durable copper heating elements are another plus, designed for longevity and ease of service.

Rating
9.5
Power (kW)
Temperature Rise
Installation Requirements

Most important from
1969 reviews

Power (kW)
Was cheaper than Home Depot and pulls about 8kW upon use.
Temperature Rise
You may feel the need to set the temp to 145°F, but you don't unless using multiple hot water devices simultaneously.
Installation Requirements
Installed it in a tiny house and it works wonderfully.

Buying Guide for the Best Outdoor Tankless Electric Hot Water Heaters

Choosing the right outdoor tankless electric hot water heater can significantly improve your home's energy efficiency and ensure you have a reliable supply of hot water. These heaters are designed to provide hot water on demand without the need for a storage tank, making them a great option for those looking to save space and reduce energy consumption. To make an informed decision, it's important to understand the key specifications and how they relate to your specific needs.
Flow Rate (GPM)Flow rate, measured in gallons per minute (GPM), indicates how much hot water the heater can produce at a given time. This is crucial because it determines whether the heater can meet your household's hot water demands. For example, a flow rate of 2-3 GPM is suitable for small households or single applications like a shower, while 4-6 GPM can handle multiple fixtures simultaneously. To choose the right flow rate, consider the number of people in your home and the number of hot water fixtures you expect to use at the same time.
Power (kW)The power rating, measured in kilowatts (kW), indicates the heater's capacity to heat water. Higher kW ratings mean the heater can heat water more quickly and handle higher flow rates. For small households or low-demand applications, a unit with 10-15 kW may suffice. For larger households or higher demand, look for units with 18-27 kW. Assess your household's hot water usage patterns to determine the appropriate power rating for your needs.
Temperature RiseTemperature rise refers to the increase in water temperature that the heater can achieve. This is important because it affects how hot the water will be when it reaches your fixtures. A higher temperature rise is needed in colder climates where incoming water temperatures are lower. For moderate climates, a temperature rise of 30-40°F may be sufficient, while colder regions may require a rise of 50-70°F. Consider your local climate and the desired hot water temperature when evaluating this spec.
Energy EfficiencyEnergy efficiency measures how effectively the heater converts electrical energy into hot water. Higher efficiency ratings mean lower energy consumption and reduced utility bills. Look for units with efficiency ratings of 90% or higher for the best performance. To choose the right efficiency level, consider your long-term energy savings and environmental impact goals.
Installation RequirementsInstallation requirements include the electrical specifications and space needed for the heater. Outdoor tankless electric heaters typically require a dedicated electrical circuit and proper ventilation. Ensure your home's electrical system can support the heater's power requirements and that you have adequate space for installation. Consulting with a professional installer can help you determine if your home meets these requirements.
Durability and WarrantyDurability and warranty are indicators of the heater's longevity and the manufacturer's confidence in their product. Look for heaters made with high-quality materials and those that offer a comprehensive warranty, typically ranging from 5 to 10 years. A longer warranty can provide peace of mind and protection against potential issues. Consider the reputation of the manufacturer and read customer reviews to gauge the reliability of the heater.

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