10 Best Tankless Water Heaters 2026 in the United States

The Rheem 18kW 240V Tankless Electric Water Heater is a compelling option for those looking for an efficient, easy-to-install solution for their hot water needs. One of its standout features is the external digital thermostatic control with an LED display, which offers precise temperature control with +/- 1 degree accuracy. This makes it user-friendly and ensures you always get the perfect water temperature.

Its advanced self-modulation technology is another highlight, as it adjusts power usage based on your hot water demand, contributing to energy efficiency and potentially reducing your energy bills over time. The unit's flow rate is up to 4.4 gallons per minute (GPM), which should be sufficient for small to medium households but might not meet the demands of larger families with high simultaneous water usage.

The heater uses durable copper immersion heating elements that are field-serviceable, enhancing its longevity and ease of maintenance. Installation is straightforward with bottom 3/4 inch NPT water connections and threaded design, making it simple to replace existing water heaters. The compact size (14.5 inches wide and 18.25 inches high) allows it to fit in tight spaces, adding to its versatility. However, as an electric unit, it may not be as powerful as gas models in terms of temperature rise, especially in very cold climates.

The Rheem RTEX-24 24kW 240V Electric Tankless Water Heater offers a robust solution for continuous hot water supply with its impressive flow rate of up to 5.9 gallons per minute, making it suitable for households with moderate to high hot water demands. One of its standout features is the 99.8% energy efficiency, which helps in reducing energy costs and promoting eco-friendliness. The electric fuel type simplifies installation and maintenance compared to gas models, although it does require a 240V electrical connection, which some homes may need to upgrade to accommodate.

The compact dimensions (17.63”W x 18.25”H x 3.5”D) and wall-mount design make it space-efficient and ideal for small utility areas, while the digital temperature display and ON/OFF dial control provide ease of use and precise temperature adjustments. Additionally, the self-modulating power control enhances efficiency by only using the necessary amount of power based on the water flow rate.

However, the temperature rise might be limited during peak usage in colder climates, potentially requiring additional units for larger homes. Potential buyers should consider the installation requirements and whether their household electrical setup can support the unit. Those looking for a reliable, energy-efficient, and continuous hot water supply will find the Rheem RTEX-24 a compelling option, especially in moderate climates and homes with appropriate electrical infrastructure.

The Rheem RTGH Series 8.4 GPM tankless water heater is a robust option for households seeking an efficient and high-capacity water heating solution. With a maximum flow rate of 8.4 gallons per minute, it is capable of handling the hot water needs of multiple fixtures simultaneously, making it suitable for larger families or homes with high hot water demand. Its energy efficiency rating of 0.93 ensures that it converts a significant portion of its fuel into heat, helping to reduce energy bills over time. The unit operates on natural gas and requires a 120-volt power source for its electric ignition, combining the efficiency of gas heating with the reliability of electric controls.

Measuring 17.7 inches in width and 23.7 inches in height, the unit is relatively compact, though it does require wall mounting, which might be a consideration during installation. The temperature settings can be adjusted between 100 and 140 degrees Fahrenheit, with a default setting of 120 degrees Fahrenheit, providing flexibility to meet different hot water needs. It comes with a solid warranty package, including 1 year for labor, 15 years for the heat exchanger, and 5 years for parts, which speaks to the manufacturer's confidence in the product's durability.

On the downside, at nearly 60 pounds, it is a bit heavy, which might pose a challenge during installation. Additionally, while it ranks #94 in water heaters, this model is a reliable and efficient choice for those who need a powerful and flexible water heating solution but should be prepared for the installation requirements.