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

The Rheem RTEX-24 is a solid choice for anyone looking for an electric tankless water heater, particularly for residential use. One of its key strengths is its impressive flow rate of up to 5.9 gallons per minute, making it suitable for medium to large households where multiple hot water outlets may be used simultaneously. Its self-modulating power control ensures that the heater adjusts energy use based on demand, which can help in energy savings. With an energy efficiency rating of 99.8%, this unit can significantly reduce your utility bills compared to traditional tank heaters.

The adjustable digital temperature display is user-friendly, allowing for easy temperature adjustments to find that just-right warmth. The compact design, with dimensions that allow for wall mounting, can save space in smaller homes.

There are a few considerations to keep in mind. The installation might require a professional, especially if you’re not handy, as it involves electrical connections that must be done correctly for safety. Additionally, while the heater’s specifications are strong, it may struggle if you have high hot water demands at multiple points at once, depending on the temperature rise needed and your incoming water temperature. Lastly, Rheem provides a warranty, but it's always good to check the specifics to ensure you’re covered in case of any manufacturing defects. If you’re seeking a reliable and efficient hot water heater for your home, the Rheem RTEX-24 is certainly worth considering.

The Rheem 18kW 240V Tankless Electric Water Heater is designed to offer an on-demand hot water solution for homeowners looking to save space and energy. With a flow rate of up to 4.4 gallons per minute (GPM), it can efficiently supply hot water for multiple outlets at once, making it suitable for medium-sized households or apartments. One standout feature is its external digital thermostatic control with a precise +/- 1 degree accuracy, allowing users to easily set their desired water temperature.

The self-modulation technology adjusts the power based on your hot water needs, optimizing energy use and maintaining efficiency, which is an impressive 99.8%. This means you can enjoy hot water without worrying too much about energy bills.

Installation is relatively straightforward with its wall-mount design and 3/4 inch NPT connections which simplify the setup process. The durable copper heating elements are also field-serviceable, contributing to the unit’s longevity. There are a few drawbacks to consider. The unit requires a 240V power supply and an adequate electrical setup, which might necessitate professional installation if your home isn’t equipped. It may not be powerful enough for larger households or homes with high demand for simultaneous hot water use.

The Stiebel Eltron Tempra 29 Plus is a powerful electric tankless water heater designed to provide a continuous and unlimited supply of hot water on demand. With a maximum flow rate of 3 gallons per minute, it is suitable for households needing hot water for multiple faucets or a shower simultaneously, but might be tight for larger families running several fixtures at once. Its temperature rise capability ensures hot water even in colder climates, and the unit offers two temperature memory presets for quick, personalized settings.

This model requires a substantial electrical setup: it needs hard-wired 240 or 208-volt service with three dedicated 40 amp breakers and at least a 200 amp total service to your home. Installation may be more complex and potentially costly if the current electrical system isn’t equipped for it. However, the compact and sleek wall-mounted design saves space and doesn’t need any venting, which is convenient for many homes.

Energy efficiency is a strong point here—the heater is highly efficient, helping reduce electricity consumption compared to traditional tank heaters. The LED display adds ease of use by clearly showing temperature settings. At 19 pounds and moderate size, it is manageable for wall mounting. The unit includes important safety and quality certifications (CSA, NSF, UL) and comes from a reputable brand.