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 Stiebel Eltron Tempra 20 Trend is a compact and energy-efficient electric tankless water heater designed to deliver continuous on-demand hot water. With a power rating of 19.2 kW and a maximum flow rate of about 2 gallons per minute, it suits small to medium households that need steady hot water without storage tanks. It can heat water up to 140°F, allowing you to adjust the temperature easily through its digital LED display. The unit’s auto-modulation feature helps save energy by adjusting power use based on demand, making it eco-friendly and cost-effective for daily use.

Its sleek, wall-mounted design doesn’t require venting, saving space and simplifying installation, although it does require a 240V power supply with a minimum 125A electric service, which might need professional evaluation for older homes. The heater operates silently thanks to its solid copper heating element, adding to user comfort. Additionally, it comes with a strong warranty—7 years against leaks and 3 years on parts—which reflects confidence in its reliability.

A limitation to consider is the flow rate of 2 GPM, which might be insufficient if multiple bathrooms or simultaneous heavy water use is common, potentially struggling to keep up during high demand. Also, the electrical requirements mean installation costs could be higher if your home’s wiring isn’t already compatible. This model is well suited for those seeking a space-saving, energy-efficient electric water heater with reliable temperature control, particularly in homes where moderate hot water flow meets daily needs without interruptions.