10 Best Electric Tankless Water Heater 2026 in the United States

The Rheem 18kW 240V Tankless Electric Water Heater is a solid choice for those looking for an efficient and space-saving water heating solution. One of its standout features is the impressive flow rate of up to 4.4 gallons per minute (GPM), which makes it suitable for smaller households or apartments where demand for hot water isn't excessively high. Its energy efficiency rating of 99.8% is quite remarkable, meaning you'll likely save on your energy bills compared to traditional tank heaters. The self-modulation technology adjusts the power based on hot water demand, which further optimizes energy use.

The external digital control with an LED display is user-friendly, allowing for precise temperature settings within a +/- 1-degree accuracy. This feature is particularly beneficial for those who want to maintain consistent hot water temperatures. The installation is straightforward as well, with bottom connections that make it easier to replace or service when needed.

There are a few drawbacks to consider. While the 4.4 GPM flow rate is adequate for smaller setups, larger families or homes with multiple bathrooms may find it insufficient during peak usage times. Additionally, being an electric unit, it may not be the best option for locations where electricity supply is unreliable or insufficient to support its high wattage of 18,000 watts. Lastly, while the unit is compact, its installation does require adequate space and professional help, especially for wall mounting, which could be a consideration for DIY enthusiasts.

The Rheem RTEX-24 Electric Tankless Water Heater offers a powerful solution for those seeking on-demand hot water. With a 24kW power rating and a maximum flow rate of 5.9 gallons per minute, it is capable of providing continuous hot water for multiple applications simultaneously. The self-modulating power control is a standout feature, allowing for energy-efficient operation by adjusting the power usage based on the actual demand. Additionally, its energy efficiency rating of 99.8% ensures minimal energy wastage, which can lead to lower utility bills over time.

The digital temperature display and ON/OFF dial control make it easy to adjust and monitor the temperature settings, enhancing user convenience. The compact size (17.63 inches wide, 18.25 inches high, and 3.5 inches deep) and wall-mount installation method make it suitable for homes with limited space. However, it is important to note that the unit requires a 240V electrical connection and professional installation is recommended to ensure optimal performance and safety.

While it is a highly efficient and effective water heater, its performance may vary depending on the incoming water temperature and the number of simultaneous hot water demands. Given its robust features, the Rheem RTEX-24 is well-suited for households looking for a reliable and efficient electric tankless water heater but may not be ideal for larger homes with high hot water consumption.

The Stiebel Eltron Tankless Water Heater - Tempra 24 Plus is a solid choice for anyone looking for an electric water heater that offers on-demand hot water. One of its standout features is the continuous flow technology that ensures a consistent water temperature, making it ideal for families who need uninterrupted hot water during showers or other tasks. With its compact design, this unit saves space, and since it doesn’t require venting, installation is generally straightforward, which can be a major plus for homeowners.

Energy efficiency is another strong point, as it utilizes auto-modulation to control water flow and reduce energy consumption. The included savings monitor is a nice touch, helping you track energy savings over time. Additionally, the digital temperature display and preset options enhance usability, making it easy to adjust settings to your preference. The safety feature allowing you to limit the maximum temperature is a thoughtful addition, particularly for homes with young children.

On the downside, you need to ensure your electrical system can support this unit, as it requires a minimum service of 150 amps, which may necessitate an upgrade for some homes. While it performs well within its capacity, it’s important to note that the flow rate may decrease if multiple outlets demand hot water simultaneously, so larger households with high simultaneous usage might experience some limitations. The warranty offered provides peace of mind, covering leakage for seven years and parts for three years, indicating the manufacturer’s confidence in the product’s durability. Potential buyers should consider whether the installation costs and electrical requirements align with their home setup. The Tempra 24 Plus is a reliable, energy-efficient option for those who need a steady supply of hot water and have compatible electrical infrastructure.