10 Best Tankless Gas Water Heaters 2026 in the United States

The Rinnai RXP199iN tankless water heater offers a notable blend of versatility and efficiency. Its capacity to deliver up to 11.1 GPM makes it suitable for households with high hot water demands, potentially serving up to seven fixtures simultaneously. This high flow rate, coupled with a substantial 199,000 BTU rating, ensures a consistent supply of hot water even during peak usage times. The energy efficiency factor (UEF) of .98 indicates the unit is highly efficient, contributing to lower energy bills over time and making it an eco-friendly choice.

Additionally, the unit's compact size, comparable to a small suitcase, facilitates flexible installation options, whether indoors or outdoors, thanks to the Versa Vent system and the Smart Sense gas control system accommodating both natural gas and propane. The Smart-Circ Intelligent Recirculation feature is a standout, learning your water usage patterns to optimize efficiency and convenience by scheduling pump and recirculation activities.

While the design is user-friendly with features like an easy-to-use interface and Quick Flush function, professional installation is strongly recommended. This might be a drawback for those looking for a DIY solution and could add to the initial setup cost. Another potential downside is the need for an additional Control-R module for WiFi connectivity, which isn't included with the unit. This water heater is ideal for larger homes or any setting requiring a substantial and steady hot water supply, especially for users who prioritize energy efficiency and modern conveniences.

The Rinnai RX199iN is a highly efficient tankless gas water heater ideal for those seeking a reliable and space-saving hot water solution. With a flow rate of up to 11.1 gallons per minute (GPM), it can support multiple fixtures simultaneously, making it suitable for larger households or homes with high hot water demands. Its impressive BTU rating of 199,000 ensures rapid heating, and its energy efficiency with a UEF of 0.98 means lower utility bills over time.

One of the standout features of the RX199iN is its adaptability; it can be installed indoors or outdoors and operates on either natural gas or propane. This flexibility is enhanced by the Smart Sense gas control system, providing ease of use and efficient performance. The compact design, comparable to a small suitcase, allows for installation in various spaces without compromising on performance.

There are considerations to keep in mind. The installation process is best handled by professionals, which can add to the initial cost. Additionally, while the heater is efficient, users should verify that their home's ground water temperature aligns with the heater's capabilities for optimal performance. Access to Wi-Fi control features requires purchasing additional modules, which might be a drawback for some users seeking comprehensive smart home integration.

The Rinnai RE180iN is a compact indoor tankless natural gas water heater designed to deliver up to 8.5 gallons per minute (GPM), which means it can comfortably supply hot water to multiple fixtures at once, making it suitable for medium to larger households. Its 180,000 BTU rating indicates strong heating power, allowing it to provide a good temperature rise even when the incoming water is cold. With an energy factor (EF) of 0.82, it is fairly efficient for a non-condensing model, helping you save on energy costs compared to traditional water heaters.

The unit’s slim size (about 14 by 27 inches) fits well in smaller indoor spaces, though professional installation is recommended due to venting needs and complexity. The LED display is a helpful feature that provides service reminders and error codes, making maintenance easier. Being a non-condensing model means it might be less efficient than condensing types, which recover more heat from exhaust gases. Also, it requires proper venting, which could limit installation options or add to installation costs.

The warranty coverage is solid, with up to 15 years on the heat exchanger. If you want a reliable, space-saving tankless water heater with good flow and heating power for your indoor setup and don’t mind professional installation, the Rinnai RE180iN is a strong choice. Just keep in mind that higher upfront installation and venting requirements might be factors to consider.