10 Best Tankless Hot Water Heaters 2025 in the United States

The Rinnai RXP199iN is a versatile tankless water heater designed for both indoor and outdoor use, thanks to its Versa Vent system. It runs on either natural gas or propane, which adds flexibility depending on your fuel preference. With a strong flow rate of up to 11.1 gallons per minute, it can supply hot water to around seven fixtures simultaneously, making it suitable for medium to large households. Its energy efficiency is excellent, boasting a UEF (Uniform Energy Factor) of 0.98, which means it uses fuel very efficiently and can help reduce energy bills.

The Rheem 18kW 240V Tankless Electric Water Heater in Gray offers several appealing features for those in need of a compact and efficient water heating solution. The primary advantages of this model include its advanced self-modulation technology, which helps adjust power based on the hot water demand, ensuring energy efficiency and cost savings. Additionally, it boasts a flow rate of up to 4.4 GPM, which is suitable for small to medium households, providing enough hot water for multiple uses simultaneously.

The Rinnai RE180eP is a propane-powered outdoor tankless water heater designed to deliver hot water on demand without storing it. It offers a strong maximum flow rate of up to 8.5 gallons per minute, which is suitable for running multiple fixtures like showers and faucets at the same time in medium to larger households. Being non-condensing, it’s simpler in design but slightly less energy-efficient compared to condensing models, though it still includes features like an LED display to help with maintenance and efficiency reminders.