10 Best Tankless Gas Water Heaters 2025 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 RXP160iN is a versatile tankless gas water heater that can run on either natural gas or propane, suitable for both indoor and outdoor installation with the proper venting. It delivers up to 9 gallons per minute, comfortably supplying hot water to multiple fixtures simultaneously—a good flow rate for medium to large households. Its energy efficiency is excellent, with a UEF rating of 0.97, which helps save on energy costs compared to traditional tank water heaters. The 160,000 BTU output ensures strong heating power, capable of maintaining a high temperature rise even if incoming water is quite cold.

The unit is compact and wall-mounted, roughly the size of a small suitcase, making it a space-saving option for homes with limited installation space. One of its smart features is the internal pump with Smart-Circ technology that learns usage patterns to reduce water waste and improve convenience by delivering hot water faster when needed. Professional installation is recommended, especially because of venting requirements and gas connections, which might increase upfront costs. Additionally, outdoor installation requires an extra vent cap accessory.

The water heater offers WiFi control compatibility through an optional module, although this additional cost and setup may not be necessary for everyone. This Rinnai model is an excellent choice for users seeking reliable, energy-efficient hot water with flexible installation options and smart features, but it requires some technical know-how or professional help to install correctly.