10 Best Electric Tankless Water Heaters 2026 in the United States

The Rheem RTEX-24 24kW 240V Electric Tankless Water Heater offers solid performance for households looking for a reliable source of on-demand hot water. One of its strong points is the flow rate, with the capacity to deliver up to 5.9 gallons per minute, which should be sufficient for multiple outlets running simultaneously. The unit's self-modulating power control and adjustable digital temperature display are user-friendly features that allow for precise temperature adjustments and energy savings, contributing to its high energy efficiency rating of 99.8%. This makes it an economical choice in the long run.

Additionally, the unit is compact, with dimensions of 17.63 inches wide and 18.25 inches high, making it easier to install in various spaces. It is designed for wall mounting, which can save floor space in tight utility areas. However, the power requirements are quite high at 24kW and 240V, which means it might require an upgrade to your electrical system if your current setup isn't compatible. This could add to the installation cost and complexity.

The unit also comes with necessary fittings and aerators, which is a plus. In conclusion, the Rheem RTEX-24 is an efficient and high-capacity option suitable for those who need consistent hot water and have the necessary power infrastructure.

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 20 Plus is an electric tankless water heater designed for consistent on-demand hot water. One of its standout features is the Advanced Flow Control technology, which ensures the water temperature remains steady by slightly reducing flow if the demand exceeds the unit's capacity, meaning hot showers are uninterrupted. This heater has a sleek, compact design that saves space and doesn't require venting, making it suitable for whole-house use.

Plus, it's eco-friendly, thanks to its auto-modulation and electronic water flow control, which helps save energy, and the unit even tracks these savings for you. Operating the Tempra 20 Plus is straightforward with a noise-free electronic switch, digital temperature display, and memory buttons for preset temperatures. The unit requires significant electrical power (19.2kW, 240V, and a minimum 125A service) to operate efficiently, so ensure your home can support this. It offers a wide output temperature range of 68° to 140°F.

The installation is wall-mounted, and the heater itself is relatively light at 20.1 pounds. In terms of warranties, it comes with a 7-year leakage warranty and a 3-year parts warranty, indicating confidence in its durability. Some potential users might find its power requirements and installation needs a bit demanding. If you are looking for a reliable, efficient, and eco-friendly tankless water heater for your home, the Tempra 20 Plus is a strong contender. Just ensure your electrical system can meet its requirements.