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 unit features a safety-conscious design with a blower that adjusts automatically for efficient combustion and low noise operation. It heats water up to 149°F, which is adequate for most household needs. However, it is not recommended for use in high-altitude areas above 2,000 feet, which might limit its suitability depending on location. The product comes with a 2-year warranty and customer support, providing some peace of mind, although this warranty period is shorter compared to some competitors.

A minor downside is the requirement to drain the unit in cold weather if unused for a long time to prevent damage. If you want a reliable, energy-saving tankless heater for a family-sized home using natural gas, the Ranein offers a good balance of power, compact design, and safety features, but consider your altitude and be prepared for occasional maintenance in colder climates.

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 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.

One of the key strengths of the Tempra 24 Plus is its advanced flow control, which helps maintain consistent water temperatures even when multiple outlets are in use. This is particularly beneficial during peak usage times. The digital temperature display and preset memory buttons make it user-friendly, even for individuals who might not be tech-savvy.

However, there are a few drawbacks to consider. The unit requires a minimum electric service of 150 A, which may be a limitation for homes with older electrical systems. Installation might be tricky for DIY enthusiasts, as it typically requires a professional to handle the electric setup. Additionally, while the unit operates quietly, some users might find that the slight reduction in flow during high demand could be a minor inconvenience. The warranty provided, including a 7-Year Leakage and 3-Year Parts Warranty, adds a layer of confidence in its reliability. The Stiebel Eltron Tempra 24 Plus is a well-rounded option for those prioritizing efficiency and continuous hot water, though it's best suited for households ready for potential electrical upgrades.