10 Best Electric Tankless Hot Water Heater 2025 in the United States

The Stiebel Eltron Tempra 36 Trend is a powerful electric tankless water heater designed to provide endless hot water on demand, making it a strong choice for whole-house use. With a high wattage of 27,000 watts and operating at 240 volts, it can deliver water temperatures between 68°F and 140°F, which means it can handle significant temperature rises efficiently. Its compact size (about 16.6 by 14.5 inches) and wall-mount design help save space, and since it doesn't require venting, installation can be simpler than gas heaters.

One standout feature is its energy-saving auto-modulation, which adjusts power based on demand to reduce wasted energy. The unit operates silently and includes an easy-to-read LED temperature display, adding to user convenience. However, it requires a substantial electrical service—recommended minimum of 300 amps—which might mean electrical upgrades in some homes, making installation more costly and complicated. The heater comes with a solid 7-year warranty against leaks and a 3-year parts warranty, reflecting confidence in its durability.

While it’s highly energy-efficient and well-suited for larger households needing continuous hot water, the heavy electrical requirement and potentially higher upfront installation costs might be drawbacks for some users. If your home’s electrical system can support it, this model offers reliable performance and energy savings in a compact, quiet package.

The Stiebel Eltron Tempra 29 Trend is an electric tankless water heater designed for those seeking a continuous supply of hot water. One of its standout features is the ability to provide on-demand hot water, which means no more unexpected cold showers. With a flow rate of up to 9.5 gallons per minute, it can serve an entire household, making it ideal for families or homes with high water usage needs.

In terms of energy efficiency, this unit is a strong contender. Its sleek design not only saves space but also incorporates auto-modulation technology to minimize energy use when hot water is not needed. This makes it a great eco-friendly choice for environmentally conscious consumers. The silent operation further enhances its appeal, as it won't disrupt your home environment while in use.

The Tempra 29 Trend requires a significant electrical service of at least 200 amps, which may necessitate an upgrade to your home’s electrical system if it currently does not meet this requirement. Additionally, while it has a good warranty (7 years for leakage and 3 years for parts), some users may still worry about the initial installation costs and the need for professional setup. The digital temperature display is a convenient feature, allowing users to monitor their water temperature easily. It's compact at 16.63 inches wide and 14.5 inches high, making it suitable for various installation spaces. Potential buyers should verify that their plumbing can support a tankless unit effectively. The Stiebel Eltron Tempra 29 Trend serves as an excellent choice for those looking for reliable, efficient hot water solutions, particularly in larger households, while being mindful of the electrical demands and installation considerations that come with such a high-performance unit.

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.