10 Best Tankless Water Heaters 2025 in the United States

The Rinnai RXP199iN Condensing Smart Sense Tankless Water Heater offers impressive versatility, operating with either natural gas or propane and being suitable for both indoor and outdoor installations. With a flow rate of up to 11.1 GPM, it can handle multiple fixtures at once, making it ideal for larger households. Its compact size and modern design, which includes features like Quick Flush and Smart-Circ Intelligent Recirculation, enhance its efficiency and user-friendliness.

Additionally, the unit boasts a high energy efficiency factor of 0.98, translating to significant energy savings. The option for WiFi connectivity through the Control-R module adds to its smart appeal, although this module is not included with the water heater. Installation should be performed by a professional, which adds to the initial cost but ensures proper setup and operation. The unit's temperature rise and maximum output of 199,000 BTU make it suitable for demanding environments, but users should ensure their home’s infrastructure supports this capacity.

The warranty and support are implied to be robust through Rinnai's recommendation for professional installation and their central app for service and troubleshooting. This tankless water heater is best suited for those needing a high-performance, energy-efficient solution for a large household.

The Stiebel Eltron Tempra 36 Plus is a high-powered electric tankless water heater designed to provide continuous hot water on demand. Its 36 kW wattage supports a maximum flow rate of about 1.5 gallons per minute, which is ideal for point-of-use or smaller household setups but may struggle to supply multiple outlets simultaneously in larger homes. This model features advanced flow control and self-modulation technology that adjusts energy use to match the demand, making it energy-efficient and helping to reduce utility bills. The digital LED display allows for precise temperature adjustments, which is a convenient feature for users wanting consistent water temperature.

Being electric, it avoids the need for gas lines or ventilation, simplifying installation in many cases, though professional installation is still recommended due to electrical requirements. The compact size (approximately 16.6 by 14.5 inches) and wall-mount design make it space-saving, suitable for tight areas. Maintenance needs are relatively low compared to traditional tank heaters, but like all tankless units, it requires periodic descaling in hard water areas to maintain performance.

The Tempra 36 Plus is reliable and efficient, though its flow rate may limit its use in larger households with high simultaneous hot water demand. It is well suited for users looking for an eco-friendly, electric solution with precise temperature control and moderate flow capacity.

The FOGATTI Natural Gas Tankless Water Heater is a compact indoor unit designed for homeowners who want continuous hot water without the bulk of a traditional tank. It offers a strong flow rate of up to 7.5 gallons per minute, which can comfortably supply hot water to multiple outlets like showers and sinks at the same time. Powered by natural gas and boasting a high heat output of 170,000 BTU, it quickly heats water on demand, making it ideal for busy households.

One of its standout features is precise temperature control, thanks to advanced sensors that keep water temperature steady within 1 degree Fahrenheit. This ensures comfort whether it's cold or warm outside. The unit’s compact size (about 17 by 26 inches) and light weight make installation easier, including in homes with lower water pressure (as low as 15 PSI). It runs on standard 120V electricity, mainly for control systems, so no special electric setup is needed.

Built with durable materials like a copper heat exchanger and stainless steel burner, it promises reliability and longevity. It also comes with safety certifications (CSA) and a good warranty (2 years overall, 5 years on the heat exchanger), which adds peace of mind. However, it’s important to note that in freezing conditions below 5°F, you must drain the heater to prevent damage, which might require extra maintenance in colder climates. This heater may not be the best fit for very large homes or those above 2000 feet altitude, as performance could be affected. Also, because it’s gas-powered, proper ventilation and professional installation are necessary. If you’re seeking an energy-efficient, space-saving solution for steady hot water in a mid-sized home with natural gas, the FOGATTI model offers a strong balance of power, precision, and convenience.