10 Best Electric Tankless Water Heaters 2025 in the United States

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 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 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.