10 Best Electric On Demand Water Heater 2025 in the United States

The Stiebel Eltron Tempra 20 Plus Tankless Water Heater offers some impressive features that address key needs for an electric-on-demand-water-heater. It has a flow rate of up to 3.79 liters per minute, which should be sufficient for most households. The power rating of 19.2 kW ensures that it can deliver a significant temperature rise, keeping your showers hot even if demand fluctuates. The advanced flow control technology helps maintain a consistent water temperature, providing comfort and preventing interruptions during hot showers.

Energy efficiency is a strong point as well; the unit has auto-modulation and electronic flow control, and a savings monitor helps track energy costs, making it eco-friendly and potentially cost-effective in the long run. It's compact and wall-mountable, saving space without the need for venting, which can be a big advantage for smaller homes or apartments. The installation requires a minimum 125 A electric service, which might necessitate an upgrade for some homes. The digital temperature display and preset buttons make operation straightforward, and the unit runs quietly.

The warranty is robust, offering 7 years against leakage and 3 years for parts, which provides some peace of mind. However, the maximum flow rate of 3.79 liters per minute may not suffice for larger households with multiple simultaneous hot water demands. Additionally, while it is energy-efficient, the initial cost and potential need for electrical upgrades might be a consideration for some users. This unit is best suited for average-sized homes that require a reliable and efficient solution for on-demand hot water.

The Rheem 18kW 240V Tankless Electric Water Heater is a solid option for those looking to efficiently supply hot water on demand. With a flow rate of up to 4.4 gallons per minute (GPM), it can cater to smaller households or applications requiring moderate hot water supply, making it ideal for apartments or homes with limited space.

One of its strengths is the 99.8% energy efficiency, which means it consumes less energy compared to traditional water heaters. This can help save on electricity bills over time. The unit features an external digital thermostatic control with an LED display, allowing users to set temperatures with +/- 1 degree accuracy, which is a handy feature for precise control and comfort. The self-modulating technology adjusts the power based on the demand for hot water, ensuring consistent performance. Additionally, the durable copper immersion heating elements are field-serviceable, which can simplify maintenance and repair.

However, there are some limitations to consider. The maximum flow rate of 4.4 GPM may not be sufficient for larger households or simultaneous high-demand situations, such as running multiple showers at once. Also, while the installation is straightforward with bottom water connections, it may still require professional assistance for optimal setup, especially for those unfamiliar with plumbing. It’s also worth noting that while the product dimensions are compact (14.5 inches wide and 18.25 inches high), its wall-mounted design might not suit every installation preference.

The EcoSmart ECO 11 Electric Tankless Water Heater is a compact and efficient solution for providing on-demand hot water for smaller applications such as a bathroom, small sink, or office breakroom. It boasts a maximum flow rate of 3.1 gallons per minute (GPM) and a power rating of 13 kW, ensuring it can deliver consistent hot water without running out. The patented self-modulating technology helps maintain the water temperature within 1 degree of the selected setting, enhancing efficiency and performance.

One of the standout features is its energy efficiency, with a reported 99% thermal efficiency, meaning it only heats water when needed, which can save on energy bills over time. Additionally, its small size (11.5 x 8 x 3.75 inches) makes it easy to install on a wall or at the point of use, saving valuable space compared to traditional tank heaters. The LED display adds convenience by providing clear temperature readings. However, it’s important to note that its effectiveness varies with the inlet water temperature and is best suited for low-flow applications. It may not be ideal for larger households or demanding hot water needs.

The product comes with a lifetime warranty on electronics, exchanger, and element, although it doesn’t cover labor costs or incidental damages. The EcoSmart ECO 11 is a reliable, energy-efficient option for users needing an on-demand water heater for smaller settings.