10 Best Tankless Hot Water Heaters 2026 in the United States

The Stiebel Eltron Tempra 29 Plus is an electric tankless water heater that offers a continuous, on-demand supply of hot water with a maximum flow rate of about 3 gallons per minute. This makes it a suitable choice for small to medium households needing hot water for a couple of fixtures simultaneously, such as a shower and a sink. One of its strengths is high energy efficiency, which helps save on electricity bills compared to traditional tank heaters. Its compact, wall-mounted design fits well into spaces where saving room is important, and the LED display with two temperature memory presets adds convenience for personalized comfort.

Installation requires a significant electrical setup: it needs hard-wired 240-volt service with three dedicated 40-amp breakers and substantial wiring, which might increase upfront costs and complexity. Therefore, it may not be ideal for homes without a robust electrical system already in place. The heater is certified for safety and quality, and the brand is well-regarded.

While it does not offer a very high flow rate for large families or multiple simultaneous uses, its efficient and reliable performance makes it well suited for those prioritizing energy savings and space efficiency in an electric tankless water heater.

The Rinnai RE199iN is a natural gas tankless water heater designed for indoor use, offering a strong flow rate of up to 9.8 gallons per minute (GPM). This means it can handle multiple fixtures at once, making it suitable for larger households or homes with higher hot water demand. It operates efficiently by heating water only when needed, which can help reduce energy waste compared to traditional tank heaters. The unit has a powerful 199,000 BTU output, supporting a good temperature rise for most household needs, with a maximum temperature of 140°F. Its compact size (about the size of a small suitcase) allows for easier installation on a wall, saving space in your home. However, professional installation is recommended due to the gas connection and complexity, which is common for gas-powered tankless heaters. The product includes a solid warranty: 15 years on the heat exchanger, 5 years on labor, and 1 year on parts, giving confidence in its durability.

The LED display provides helpful service reminders and error codes, simplifying maintenance. While this model does not include WiFi control, there is an option to add it with a separate module. This water heater is a strong choice if you want an energy-efficient, high-capacity natural gas unit and have access to professional installation. If you require a model with a built-in pump or WiFi, you might consider related versions in the Rinnai range.

The Rheem RTGH-95DVLN-3 is a robust tankless water heater designed for residential indoor use with natural gas. Its standout feature is the impressive flow rate, ranging from 0.4 to 9.5 gallons per minute (GPM), making it suitable for larger households with higher hot water demands. The energy efficiency is also notable at 0.93, meaning it can help reduce energy bills compared to traditional water heaters.

The unit requires 120 volts for operation and includes an electric ignition, adding convenience and reliability in starting the heater. Temperature settings are flexible, ranging from 100 to 140 degrees Fahrenheit, catering to various preferences and needs, with a default setting of 120F. The size is relatively compact at 17.7 inches wide and 23.7 inches high, which can be a good fit for many installation spaces, though it is somewhat heavy at 59.9 pounds, which might make installation a bit challenging for some users. The integrated digital display is a useful feature for monitoring and adjusting settings easily.

However, the warranty coverage could be better; while the heat exchanger is covered for 15 years, labor is only covered for one year, and parts for five years. Potential buyers should weigh its benefits against the warranty limitations and installation considerations.