10 Best Electric Tankless Water Heater 2025 in the United States

The Stiebel Eltron 239223 Tempra 29 Plus is a high-performing electric tankless water heater that provides an on-demand and continuous supply of hot water. It features a sleek, space-saving design and does not require venting, which makes it versatile for various home installations. This model has a maximum flow rate of 3 gallons per minute (GPM), making it suitable for households with moderate hot water needs.

Its power rating is substantial, operating at 28.8 kW, which ensures a quick temperature rise but also means it requires a significant electrical setup: 240-volt service, three dedicated 40 amp breakers, and at least 200 amp total service to the home. This could be a hurdle for some installations and might require professional electrical work to update the home's capacity.

The unit features two temperature memory presets, providing convenience for users with different hot water preferences. It also has a useful LED display for easy monitoring and adjustments. Energy efficiency is a highlight, as tankless systems generally save on energy compared to traditional tank heaters by only heating water as needed. Potential buyers should consider the installation requirements carefully. This unit is most beneficial for medium to large households that can support the electrical demands, and who are looking for a reliable, space-saving, and energy-efficient solution for their hot water needs.

The Rheem 18kW 240V Tankless Electric Water Heater is a solid choice for those looking for an efficient and space-saving water heating solution. One of its standout features is the impressive flow rate of up to 4.4 gallons per minute (GPM), which makes it suitable for smaller households or apartments where demand for hot water isn't excessively high. Its energy efficiency rating of 99.8% is quite remarkable, meaning you'll likely save on your energy bills compared to traditional tank heaters. The self-modulation technology adjusts the power based on hot water demand, which further optimizes energy use.

The external digital control with an LED display is user-friendly, allowing for precise temperature settings within a +/- 1-degree accuracy. This feature is particularly beneficial for those who want to maintain consistent hot water temperatures. The installation is straightforward as well, with bottom connections that make it easier to replace or service when needed.

There are a few drawbacks to consider. While the 4.4 GPM flow rate is adequate for smaller setups, larger families or homes with multiple bathrooms may find it insufficient during peak usage times. Additionally, being an electric unit, it may not be the best option for locations where electricity supply is unreliable or insufficient to support its high wattage of 18,000 watts. Lastly, while the unit is compact, its installation does require adequate space and professional help, especially for wall mounting, which could be a consideration for DIY enthusiasts.

The Rheem RTEX-24 Electric Tankless Water Heater offers a powerful solution for those seeking on-demand hot water. With a 24kW power rating and a maximum flow rate of 5.9 gallons per minute, it is capable of providing continuous hot water for multiple applications simultaneously. The self-modulating power control is a standout feature, allowing for energy-efficient operation by adjusting the power usage based on the actual demand. Additionally, its energy efficiency rating of 99.8% ensures minimal energy wastage, which can lead to lower utility bills over time.

The digital temperature display and ON/OFF dial control make it easy to adjust and monitor the temperature settings, enhancing user convenience. The compact size (17.63 inches wide, 18.25 inches high, and 3.5 inches deep) and wall-mount installation method make it suitable for homes with limited space. However, it is important to note that the unit requires a 240V electrical connection and professional installation is recommended to ensure optimal performance and safety.

While it is a highly efficient and effective water heater, its performance may vary depending on the incoming water temperature and the number of simultaneous hot water demands. Given its robust features, the Rheem RTEX-24 is well-suited for households looking for a reliable and efficient electric tankless water heater but may not be ideal for larger homes with high hot water consumption.