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 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.