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 Rinnai RX199iN is a robust tankless water heater that is designed for both indoor and outdoor installation, offering flexibility in its setup. With a flow rate of up to 11.1 gallons per minute, it effectively supports multiple fixtures simultaneously, making it a great choice for larger households or those with high hot water demands. Its high energy efficiency rating of UEF .98 means you can expect notable savings on energy bills over time, which is especially beneficial for eco-conscious users.

This model is powered by either natural gas or propane, catering to various fuel types, which adds to its versatility. The compact design, similar to a small suitcase, helps save space in your home, a feature that many customers find appealing.

Professional installation is recommended, which could add to the cost and effort involved in setting it up. While the Rinnai Central App offers support for setup and troubleshooting, the WiFi control module is sold separately, which might be an inconvenience for users looking for a fully integrated smart home solution. Potential buyers should evaluate their specific hot water needs against the maximum temperature output of 140 degrees Fahrenheit. The warranty and support options are also crucial to consider, as they ensure peace of mind and assistance should any issues arise.

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.