10 Best Tankless Hot Water Heaters 2025 in the United States

The Rinnai RX199iN is a powerful tankless water heater that stands out for its impressive flow rate of up to 11.1 gallons per minute, making it suitable for homes with multiple fixtures needing hot water simultaneously. It's designed to operate on either natural gas or propane, giving you flexibility depending on your fuel source. The energy efficiency is top-notch, boasting a UEF rating of .98, which means it uses energy very effectively, potentially saving you on utility bills.

One of the great features is its compact size, comparable to that of a small suitcase, making it easier to fit into various spaces. The Smart Sense gas control system adds convenience, allowing for easier operation. However, the installation of this unit is recommended to be done by a professional. While this ensures safety and proper functionality, it could increase your expenses if you don’t have a technician readily available.

While its high efficiency is a significant advantage, it may not be the best choice for all water temperature needs depending on your region’s groundwater temperature. Additional considerations include the need for the RX-OVC vent cap for outdoor installation, which adds to the installation complexity and cost. Also, the Controlr module for WiFi control is sold separately, which might be a drawback for those looking for smart home integration right out of the box. If you are looking for a tankless heater that offers high performance and efficiency, the Rinnai RX199iN is a strong contender. Just ensure you’re prepared to handle the installation requirements and additional features you may want to consider.

The Stiebel Eltron Tempra 29 Trend is a strong contender in the tankless hot water heater market, particularly suitable for those seeking an efficient and space-saving solution for whole-home hot water needs. Its continuous flow feature ensures that you won’t run out of hot water during showers or while using multiple taps, which is a significant advantage for larger households. The energy efficiency of this model is commendable, with auto-modulation that helps save power when hot water is not in demand, making it an eco-friendly option.

One of the standout features is its compact size, enabling easy installation without the need for venting, which is a great plus for homes with limited space. Additionally, the silent operation means you can enjoy hot water without any distracting noise, adding to your comfort.

The digital temperature display is user-friendly, allowing for easy adjustments. The manufacturer's warranty, which includes a 7-year leakage and 3-year parts warranty, is a positive aspect, giving buyers peace of mind regarding durability and support.

The Rheem RTGH-95DVELN-3 Super High Efficiency Condensing Indoor Tankless Natural Gas Water Heater is designed for those who need a reliable and efficient hot water solution for their entire home. With a flow rate of 9.5 gallons per minute, it can handle multiple applications simultaneously, making it ideal for larger households or busy families. Its energy efficiency is impressive, as it only operates when hot water is needed, leading to potential savings on energy bills.

One of the standout features is the built-in EcoNet Wi-Fi technology, which allows users to monitor and control settings from their smartphone. This includes tracking water usage and receiving maintenance alerts, which adds a layer of convenience. The LeakGuard system is another excellent feature, proactively preventing water damage by detecting internal leaks.

In terms of installation, the Rheem model is compact and designed for indoor mounting, which can be a plus if space is limited. However, it does require natural gas as a fuel type, limiting options for those without gas lines or who prefer electric heating. While the product has many strengths, there are a few drawbacks to consider. The initial cost may be higher than traditional water heaters, and professional installation is recommended, which could add to the expense. Additionally, while the maximum temperature of 140 degrees Fahrenheit is sufficient for most household needs, some users may desire higher settings.