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 FOGATTI Natural Gas Tankless Water Heater is designed to deliver strong performance in a compact indoor unit, making it a good choice for households that need simultaneous hot water supply to multiple points like showers and sinks. It offers a high flow rate of up to 7.5 gallons per minute (GPM), which means it can handle several uses at once without running out of hot water. Its powerful 170,000 BTU rating supports quick heating, ensuring instant hot water, which is great for busy families or multitasking use. The unit features precise temperature control that keeps water temperature steady within about 1 degree, so you won’t experience sudden hot or cold bursts.

The heater is compact, taking up significantly less space than traditional tanks, and is relatively easy to install indoors, working with lower water pressures down to 15 PSI which is helpful for homes with weaker water systems. It runs on natural gas and requires standard 120V power for controls. The unit is made with durable materials like copper and stainless steel, backed by CSA certification and safety features, which adds to its reliability and longevity. It also includes a 2-year full warranty and 5 years on the heat exchanger, giving some peace of mind for maintenance.

This model is recommended for use below 2000 feet altitude and needs draining if unused in freezing temperatures to prevent damage, making it best suited for typical indoor environments without extreme cold exposure. Its energy efficiency and space-saving design are advantageous; however, installation must meet venting requirements for gas models, which might require professional help. This model is well suited for homeowners seeking a high-capacity, space-saving tankless water heater that provides steady, on-demand hot water for multiple points in the house.