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 Rheem 3.5kW 120V Point of Use Thermostatic Tankless Electric Water Heater is designed for small, low flow applications like bathrooms, offices, or wet bars where space-saving is important. Its compact size, roughly 98% smaller than typical electric water heaters, makes it easy to install in tight spots. It operates on standard 120 volts but needs a dedicated 30-amp double pole breaker, so be sure your electrical setup can support this.

The unit delivers up to 0.9 gallons per minute, which is enough for a single sink but not suitable for multiple fixtures or whole-house use. You can adjust the temperature precisely between 80 and 140°F, helping ensure consistent and comfortable hot water. Installation is straightforward since it mounts on the wall upright and requires no venting. Energy efficiency is high, which helps save on electricity bills over time.

This heater is excellent for point-of-use tasks and small spaces; however, its low flow rate and limited power mean it won’t meet the needs of larger households or high-demand situations. The product's solid 4.2-star rating from thousands of users indicates good reliability and satisfaction. If you need a compact, energy-efficient solution for occasional hot water close to the fixture, this Rheem model is a practical choice.