10 Best Tankless Water Heaters 2025 in the United States

The Ranein Natural Gas Tankless Water Heater is designed for indoor use and offers a strong heating capacity of 190,000 BTU with a maximum flow rate of 7.4 gallons per minute (GPM). This means it can comfortably supply hot water to multiple outlets (around 4-6), making it suitable for medium to larger households. Using natural gas as fuel, it is energy-efficient by providing hot water on demand without the need for a storage tank, which helps reduce energy waste compared to traditional tanks. The compact size (just over 24 inches tall and 15 inches wide) allows it to fit in small spaces and supports easy wall mounting, a plus if space is limited. Installation is simplified with standard 3/4" NPT fittings, though professional help could still be needed for correct setup.

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.

The Stiebel Eltron Tempra 24 Plus is a solid choice for those in need of an electric tankless water heater suitable for whole-house applications. Its continuous flow technology ensures that you'll have an uninterrupted supply of hot water, which is a significant advantage for larger households or those with high hot water demands. The unit is compact and energy-efficient, featuring a design that doesn't require venting, which makes it a great option if space is limited. The energy savings monitor is a nice addition, allowing you to track your energy costs effectively.