10 Best Tankless Water Heaters 2026 in the United States

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 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 Stiebel Eltron 239223 Tempra 29 Plus is an electric tankless water heater offering an efficient and reliable solution for on-demand hot water. One of its most notable strengths is its ability to provide a continuous and unlimited supply of hot water, making it ideal for households with high hot water demands. With a sleek and compact design, it saves space and does not require venting, which simplifies the installation process.

Additionally, it features two temperature memory presets for personalized adjustment and an LED display for easy monitoring. However, the installation requires a hard-wired 240 or 208-volt electric service and three separate dedicated 40 amp breakers with 8 gauge copper wiring, which could be a drawback for homes not already equipped with this setup. It has a maximum draw of 28,800 watts at 240 volts or 21,600 watts at 208 volts, emphasizing its substantial power requirement.

The maximum flow rate is 3 gallons per minute, which may be limiting if multiple hot water outlets are used simultaneously. Certified by CSA, NSF, UL, and ANSI, it ensures safety and reliability. At 24 pounds and dimensions of 16.63 inches wide by 14.5 inches high, it is relatively easy to install and manage. Given its high power capacity and specific installation requirements, this water heater is best suited for larger homes or those with significant hot water needs and an adequate electrical setup.