10 Best Tankless Electric Hot Water Heaters 2026 in the United States

The Rheem 18kW 240V Tankless Electric Water Heater is designed for those looking for an efficient and space-saving hot water solution. With a flow rate of up to 4.4 gallons per minute, it can adequately meet the hot water demands of small to medium-sized households. Its self-modulating feature intelligently adjusts the power based on your hot water needs, ensuring energy efficiency, with an impressive efficiency rating of 99.8%. This can lead to cost savings on energy bills over time.

One of its highlights is the external digital thermostatic control with an LED display, which allows for precise temperature adjustments within a degree. This user-friendly interface makes it easy to monitor and set your preferred water temperatures. Installation is a breeze as well, thanks to its wall-mountable design and straightforward connection options, making it a suitable choice for DIY enthusiasts or professional installations alike. The compact size ensures it won't take up much space, making it ideal for areas where a traditional tank heater would be cumbersome.

However, there are some considerations to keep in mind. While the flow rate is satisfactory for many, larger households or those with high simultaneous usage may find it inadequate, especially during peak demand times. Additionally, the requirement for a dedicated 240V electrical connection may necessitate an upgrade if your current setup is not compatible. The Rheem 18kW unit is a solid choice for users seeking a compact and effective tankless electric water heater, but it may not be the best fit for larger families or high-demand situations.

The Rheem RTEX-24 24kW 240V Electric Tankless Water Heater is a commendable option for delivering on-demand hot water. With a flow rate of up to 5.9 gallons per minute (GPM), it can handle multiple fixtures simultaneously, making it suitable for larger households or high-demand situations.

The adjustable digital temperature display and self-modulating power control allow for precise temperature management and efficient energy use, contributing to its impressive 99.8% energy efficiency rating. This can help to reduce electricity bills over time. Installation is relatively straightforward with its wall mount design and bottom 3/4" NPT water connections, though professional installation is recommended to ensure optimal performance and safety.

The unit's compact dimensions (17.63" wide, 18.25" high, and 3.5" deep) make it a good fit for tight spaces. However, its power requirements (240 volts and 24kW) necessitate a substantial electrical setup, which may not be suitable for all homes without electrical upgrades. The Rheem RTEX-24 offers a robust and energy-efficient solution for consistent and continuous hot water, with some considerations regarding electrical requirements.

The Stiebel Eltron Tempra 29 Plus is a powerful tankless electric water heater designed to provide an endless supply of hot water on demand, ideal for households needing continuous hot water without the bulk of a traditional tank. It can handle a maximum flow rate of about 3 gallons per minute, suitable for standard daily tasks like showering and washing dishes, though it might struggle if multiple heavy uses happen simultaneously.

This model requires a strong electrical setup—240 volts with a hefty power draw of 28,800 watts—and needs three separate 40-amp breakers, so your home’s electrical system must be capable of supporting that, which can add to installation complexity and cost. Its compact, wall-mounted design saves space and doesn’t need venting, making installation more flexible, especially in tight areas. The LED display and two temperature memory presets provide convenient, personalized temperature control. High efficiency means it uses electricity smartly, which can lower energy bills compared to less efficient heaters.

Given the wiring and breaker requirements, installation can be challenging if your home isn’t already equipped to handle such power demands. The moderate flow rate may not suit very large families or homes with simultaneous heavy water use. For modern homes with sufficient electrical capacity seeking a reliable, space-saving electric heater with precise temperature control, the Tempra 29 Plus is a solid choice.