10 Best Tankless Gas Water Heaters 2025 in the United States

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 Ranein Natural Gas Tankless Water Heater is a strong contender in the market for those seeking an outdoor tankless gas water heater. It offers a maximum flow rate of 5.3 GPM, which is suitable for a household with 3-5 outlet points, ensuring you can run multiple showers or appliances simultaneously without running out of hot water. The 130,000 BTU rating ensures a high heating capacity, making it effective for quick and efficient water heating.

Its high energy efficiency is bolstered by the automatic adjustment of the blower speed based on external conditions, optimizing gas combustion and ensuring safety with reduced noise levels and a longer lifespan. Additionally, the anti-freeze protection feature is a valuable inclusion for colder climates, preventing internal damage due to freezing.

However, it is important to note that this unit is not recommended for use at elevations over 2,000 feet, which may limit its applicability in higher altitude areas. Also, while it is easy to install with standard fittings and a compact design, the unit must be drained if not in use during cold weather to prevent damage. Another point to consider is its reliance on a 120V power supply, which should be accessible at the installation location. This water heater is an efficient and space-saving solution for many households, provided the installation requirements and altitude limitations are considered.

The Ranein Propane Gas Tankless Water Heater offers a strong performance with a heating capacity of 100,000 BTU and a hot water flow rate of 4.3 GPM, making it suitable for small to medium households. It supports multiple water supply points, which means you can run hot water in the bathroom, kitchen, and a bar area simultaneously without waiting.

One of its standout features is the Four Seasons Function, which adjusts the water temperature according to seasonal changes, ensuring a consistent water temperature year-round. Additionally, it includes a Kitchen Function for a preset 100°F output and a Bathtub Function with adjustable water output, adding to its versatility. The inclusion of an exhaust pipe in the kit is a financial plus, saving you the cost of purchasing one separately.

It also uses an oxygen-free copper water tank to minimize heat loss and enhance energy efficiency. On the downside, the unit is not suitable for installations over 2,000 feet above sea level. Also, it requires proper installation by licensed professionals, which might add to your initial costs.