10 Best Tankless Water Heaters 2026 in the United States

The FOGATTI InstaShower 9 Pro is a high-output propane tankless water heater designed especially for RVs, providing a strong 3.6 gallons per minute flow rate. This allows it to supply hot water simultaneously to both bathroom and kitchen without waiting, which is ideal for families or frequent users. It features precise temperature control within ±1°F and a built-in mixing tank that helps keep water temperature stable, enhancing comfort during showers. With a 66,000 BTU power rating, it is suitable for colder climates or higher altitudes, supported by a robust fan system that operates effectively even in windy conditions and up to 9,800 feet elevation.

Installation is fairly straightforward for RV owners replacing a tank water heater, as it fits common opening sizes and includes a 15x15 inch door and trim, plus a wired remote control for convenient temperature adjustments from inside the RV. Safety features like automatic gas shut-off, anti-freeze protection, and a pressure relief valve are built in, reducing additional costs and concerns. However, it runs on liquid propane, requiring a compatible fuel source and proper venting, which may be a consideration for those who prefer electric models.

The unit weighs around 31 pounds and is compact in size (15 inches square), but it is not smart home compatible, so remote control is limited to the included wired controller. Maintenance is simplified thanks to a dust and sand filter screen, though periodic checks and cleaning are necessary to ensure safe operation. This heater suits RVers who need reliable, instant hot water with strong flow and precise temperature control, especially when traveling in varying weather and altitude conditions.

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.