10 Best Tankless Hot Water Heaters 2025 in the United States

The Ranein Natural Gas Tankless Water Heater offers a flow rate of up to 5.3 gallons per minute (GPM), making it suitable for medium-sized households with 3-5 outlet points operating concurrently. Its 130,000 BTU heating capacity provides instant hot water without the need for preheating, which is a significant advantage over traditional tank water heaters. The energy efficiency of this unit is tied to its natural gas fuel type, which can be economical for many users.

The Ranein Natural Gas Tankless Water Heater delivers a flow rate of 3.6 gallons per minute, sufficient to supply hot water simultaneously to about two or three spots like a bathroom and kitchen. Thanks to its 80,000 BTU heating power, it provides instant hot water without the long wait common with traditional tanks. It’s designed for indoor use and includes useful safety features such as dry combustion and flame failure protection.

The Rinnai RX199iN is a powerful tankless water heater that stands out for its impressive flow rate of up to 11.1 gallons per minute, making it suitable for homes with multiple fixtures needing hot water simultaneously. It's designed to operate on either natural gas or propane, giving you flexibility depending on your fuel source. The energy efficiency is top-notch, boasting a UEF rating of .98, which means it uses energy very effectively, potentially saving you on utility bills.