8 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 RTEX-13 is a solid choice for those seeking an efficient and compact tankless electric water heater. With a maximum flow rate of 3.17 GPM, it works well for small to medium households, especially if you're looking to save space. One of its standout features is its impressive 99.8% energy efficiency, which can lead to lower utility bills over time. The external adjustable digital thermostatic control with LED display allows for precise temperature adjustments, making it user-friendly for anyone looking to set their preferred water temperature accurately.

On the installation side, this unit offers simple setup with included adapters and connections, which is a major plus for DIY enthusiasts or those wanting to avoid high installation costs. Furthermore, the durable copper immersion heating elements are field serviceable, meaning maintenance can be easier if issues arise.

However, it’s important to note a few drawbacks. While the flow rate can handle daily household needs, larger families might find the performance under heavy demand somewhat lacking, especially if multiple outlets are used simultaneously. Additionally, it requires a 240V electrical connection, which might necessitate some electrical work if your current system isn’t compatible. Also, there is no built-in battery backup, meaning you won't have hot water during power outages.