10 Best Electric Tankless Water Heaters 2025 in the United States

The Stiebel Eltron Tankless Heater – Tempra 36 Plus is a reliable choice for on-demand hot water. One of its main strengths is the ability to provide continuous and unlimited hot water, making it ideal for households with high hot water needs. Its sleek design is another advantage, as it saves space and requires no venting, making installation easier, especially in compact areas. The unit operates quietly due to its electronic switch activation, which can be a significant benefit for maintaining a peaceful home environment.

With a power requirement of 27 kW and 208 volts, ensure your home’s electrical system can support this heater, as it demands substantial power. This model also includes a LED display for easy monitoring and control, adding to user convenience. The copper-sheathed heating element housed in a copper cylinder ensures durable performance. The maximum flow rate is 1.5 gallons per minute, which might be limiting for larger households or simultaneous usage in multiple locations. However, the energy efficiency of this model is high, potentially saving on energy costs over time.

The warranty is another strong point, offering 7 years on leakage and 3 years on parts, which reflects confidence in the product's durability. Weighing 19 pounds and with dimensions of 16.63 inches wide by 14.5 inches high, it’s relatively easy to handle and install. This unit is best suited for small to medium-sized households or specific areas needing hot water on demand.

The Rheem 18kW 240V Tankless Electric Water Heater is a solid choice for those looking for an efficient and reliable source of hot water. With a maximum flow rate of up to 4.4 gallons per minute (GPM), it can meet the demands of small to medium households effectively. One of its standout features is the external digital thermostatic control with a precise +/- 1 degree accuracy, allowing users to easily set and maintain their desired water temperature.

Energy efficiency is another strong point, boasting an impressive 99.8% efficiency rating, which can help reduce electricity bills over time. The self-modulation technology adjusts power based on hot water demand, ensuring energy is used only when needed. Additionally, it is compact in size, making it suitable for installations in tighter spaces.

Installation is made easy with the bottom 3/4 inch NPT water connections and threaded fittings, which simplify the process for homeowners and professionals alike. However, it’s important to note that this model is designed for wall mounting, which may require additional considerations for some users. Some users may find that the 18kW power rating is not sufficient for larger households with multiple simultaneous hot water needs. While it serves well for typical use, those with higher demand might need to consider a more powerful unit. Additionally, it may require professional installation, which can add to the overall cost.

The Stiebel Eltron Tempra 29 Plus is a powerful electric tankless water heater designed to deliver a continuous supply of hot water on demand. It offers a maximum flow rate of about 3 gallons per minute, suitable for small to medium households or single-point applications like a shower or sink. Its high wattage (28.8 kW) supports a strong temperature rise, heating cold water efficiently to your desired temperature even in colder climates. The unit includes convenient features like two temperature memory presets and an easy-to-read LED display for simple control.

Installation requires a dedicated hard-wired 240-volt electric supply with three separate 40-amp breakers and substantial wiring, as well as a home electrical service of at least 200 amps. This means it might require an electrical upgrade if the home’s system is not already equipped, which could add to initial costs and complexity. The heater’s compact size and wall-mount design save space, and no venting is needed, making it easier to install in various locations.

Energy efficiency is high due to the on-demand heating technology, which only heats water when needed, reducing wasted energy compared to traditional tank heaters. The unit weighs 24 pounds and comes with certifications ensuring safety and quality. This model is ideal for homeowners seeking efficient, space-saving hot water solutions who have the electrical capacity or are willing to upgrade their system. It may be less suitable for very large households needing multiple hot water outlets simultaneously or for those without access to the required electrical setup.