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 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.

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.