10 Best Tankless Hot Water Heaters 2026 in the United States

The Rinnai RX130iN tankless water heater is a versatile choice for anyone needing a reliable source of hot water without the bulk of a traditional tank. It delivers up to 7.1 gallons per minute, meaning it can comfortably supply hot water to multiple fixtures at once, which is great for larger households. This model runs on natural gas or propane, making it flexible depending on your fuel preference or availability. Its energy efficiency is excellent, with a high UEF rating of 0.97, so it uses fuel very efficiently, helping keep utility costs lower.

The unit is compact, about the size of a small suitcase, and can be installed indoors or outdoors, provided you use the correct venting accessories. This makes it a good fit for various home setups but professional installation is strongly recommended to ensure safety and proper operation. The maximum temperature reaches 140°F, which is sufficient for most household needs. The built-in Smart Sense gas control helps optimize performance and safety, while features like Quick Flush make maintenance easier.

The price and installation complexity might be higher compared to simpler models, and the WiFi control option requires an additional purchase. Although it is energy-efficient, it still requires a gas connection and a 120V power source for controls. If you want a steady supply of hot water, good energy savings, and flexibility in installation with a trusted brand backing, this Rinnai model is worth considering.

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 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.