9 Best Rheem Tankless Electric Hot Water Heaters 2025 in the United States

The Rheem RTEX-24 is a solid choice for those in need of an electric tankless water heater. It boasts a powerful 24kW output, providing a flow rate of up to 5.9 gallons per minute, which is quite impressive for residential use. This means it can supply consistent hot water for multiple fixtures at once, making it ideal for larger households or situations where high demand is common. The self-modulating power feature helps in energy efficiency, ensuring that it uses only the necessary power to meet your hot water needs, with an impressive efficiency rating of 99.8%. This can lead to savings on energy bills over time.

The unit is designed for easy installation, being wall-mounted and suitable for indoor use. Its compact dimensions mean it can fit into smaller spaces without issue. The adjustable digital temperature display and ON/OFF dial control enhance user-friendliness, allowing for precise temperature adjustments.

There are some drawbacks to consider. The installation might require professional help for some users, especially if electrical work is needed to support the heater’s power requirements. Additionally, while the unit is efficient, it may struggle to provide high flow rates if multiple outlets are used simultaneously, depending on the inlet water temperature and desired output temperature.

The Rheem 18kW 240V Tankless Electric Water Heater is an excellent choice for those seeking an efficient hot water solution for their home. One of its standout features is the flow rate of up to 4.4 gallons per minute, which is sufficient for providing hot water to multiple fixtures simultaneously in smaller households. This model is known for its impressive energy efficiency, boasting a 99.8% rating, which can lead to lower utility bills over time.

The external digital thermostatic control with an LED display allows for precise temperature adjustments, ensuring consistent hot water delivery. Its self-modulating technology is another strong point, as it automatically adjusts the power based on your hot water demand, enhancing its efficiency further. Installation is straightforward with bottom 3/4 inch NPT water connections, making it accessible for both professionals and handy homeowners. The durable copper heating elements are also field serviceable, which can save costs on repairs in the long run.

There are a few considerations to keep in mind. While the flow rate is suitable for smaller households, larger homes or families might find it lacking if they require simultaneous hot water use at multiple points. Additionally, as an electric unit, it may not be the best option for users in areas with frequent power outages, as it relies solely on electricity. The warranty and customer support from Rheem are generally strong, which can give peace of mind, but it's always wise to check the specifics based on your location.

The Rheem 8kW 240V Tankless Electric Water Heater is designed to provide on-demand hot water with continuous flow, making it suitable for small households or point-of-use locations like single sinks or small bathrooms. With a flow rate of up to 1.95 gallons per minute, it delivers enough hot water for light usage but may struggle with multiple outlets running simultaneously or larger households. Its 8kW power rating ensures moderate heating capacity, while the self-modulating power control helps maintain energy efficiency by adjusting energy use based on demand.

The unit features an easy-to-use ON/OFF dial and an adjustable digital temperature display, allowing you to quickly set and monitor your preferred water temperature. Installation requires a 240V electrical supply and wall mounting, which is fairly typical for tankless electric heaters, so it is important to verify compatibility with your home's wiring. The compact size (about 8 by 12.6 inches) saves space compared to traditional tank heaters. Although exact warranty details are not specified here, Rheem products typically come with a reliable warranty, providing added peace of mind.

This unit's limited flow rate and power make it ideal for users with modest hot water needs rather than whole-house applications. It delivers energy-efficient, space-saving hot water solutions for smaller setups with straightforward temperature control.