10 Best Outdoor Tankless Electric Hot Water Heaters 2026 in the United States

The Rheem RTEX-24 is a solid option in the outdoor tankless electric hot water heater category, catering to those who need efficient and continuous hot water. With a power output of 24 kW, it boasts a flow rate of up to 5.9 gallons per minute (GPM), making it suitable for medium-sized households or light commercial use. The self-modulating power control helps maintain consistent water temperatures, which can be very beneficial for users demanding reliability.

One of the standout features is the adjustable digital temperature display, which allows you to set and monitor the water temperature easily. This gives you control and peace of mind, especially when using hot water for various tasks simultaneously. Additionally, the unit's impressive energy efficiency rating of 99.8% means lower utility bills, making it an economical choice in the long run.

If you're looking for a reliable, energy-efficient solution that provides ample hot water on demand, the Rheem RTEX-24 is a solid contender. Just be prepared for potential installation challenges.

The Rheem 18kW 240V Tankless Electric Water Heater is a solid choice for those looking for a reliable hot water solution, especially in outdoor settings. With a maximum flow rate of 4.4 gallons per minute, it’s well-suited for moderate demand, making it ideal for small to medium-sized households or outdoor applications where hot water is needed intermittently.

One of the standout features is its external digital thermostatic control with a clear LED display, allowing for precise temperature adjustments. The advanced self-modulation technology helps manage energy use effectively, which can lead to savings on electricity bills. Its impressive energy efficiency rating of 99.8% means you’re getting almost all the energy converted into hot water, which is great for eco-conscious users.

The installation process is user-friendly, thanks to the bottom 3/4 inch NPT water connections and the wall-mount design, making it a practical option for those who might consider a DIY installation. The durable copper heating elements are another plus, designed for longevity and ease of service.

The Stiebel Eltron Tempra 24 Trend is a reliable electric tankless water heater that offers continuous hot water on demand, so you won’t run out during showers. Its 24 kW power capacity and 240V requirement make it capable of providing enough hot water for whole-house use, with temperatures adjustable from 68°F up to 140°F. This model uses an advanced auto-modulation feature that helps save energy by only using the power needed at any moment. Its compact wall-mounted design frees up space and it doesn’t need venting, which simplifies installation compared to gas models. The heater operates silently, making it convenient for any home environment.

It has a clear LED temperature display and a durable internal copper heating system, which adds to its reliability. However, it does require a minimum 150 amp electrical service, so you might need an upgrade to your home’s electrical panel if it’s not already sufficient. The unit weighs about 20 pounds and measures roughly 16.6 by 14.5 inches, making it fairly easy to install on a wall. Stiebel Eltron offers a strong warranty, including 7 years against leaks and 3 years on parts, which speaks to the product’s quality.

This water heater is highly efficient and environmentally friendly, making it well suited for homeowners looking for a compact, efficient, and quiet electric tankless water heater with good temperature control and energy savings.