9 Best Whole House Tankless Electric Hot Water Heaters 2025 in the United States

The Stiebel Eltron Tankless Water Heater – Tempra 24 Plus is a robust option for homeowners looking for an electric solution to efficiently provide hot water on demand. With a flow rate of 4.0 GPM and the ability to maintain a temperature rise of up to 140°F, it can comfortably supply hot water for multiple outlets simultaneously, making it suitable for larger households. Its eco-friendly design incorporates advanced flow control technology, which adjusts the water flow to maintain a consistent temperature, ensuring that you won’t be left with a cold shower.

One of the standout features is its space-saving design. The unit is compact and does not require venting, which allows for flexible installation options. The digital display and preset temperature buttons make operation simple, even for those who may not be tech-savvy. Energy efficiency is a strong point, too, as the heater saves power through auto-modulation, and a savings monitor shows how much you’re saving on energy costs.

However, there are a few considerations to keep in mind. The Tempra 24 Plus requires a minimum electric service of 150 A, which may necessitate upgrades to your home's electrical system if it doesn't meet this requirement. Additionally, while the compact size is beneficial, it may not be suitable for very high-demand scenarios where multiple fixtures are used simultaneously at peak demand times. The warranty coverage is quite favorable, offering a 7-year leakage warranty and a 3-year parts warranty, which is reassuring for potential buyers. The Stiebel Eltron Tempra 24 Plus is a solid choice for those seeking an efficient and reliable tankless hot water heater that can provide endless hot water without the bulk of traditional systems.

The Rheem RTEX-24 is a solid choice for those looking to upgrade to a tankless electric hot water heater for their home. With a flow rate of up to 5.9 gallons per minute (GPM), it can efficiently provide hot water for multiple outlets simultaneously, making it great for medium-sized households. Its self-modulating power control ensures that you get just the right amount of energy needed for heating water, which contributes to its impressive energy efficiency rating of 99.8%. This means you can enjoy consistent, on-demand hot water without worrying too much about energy consumption.

One notable feature is its ON/OFF dial control paired with an adjustable digital temperature display, making it user-friendly. Installation is straightforward, as it is designed for wall mounting and comes with necessary fittings, although professional help might still be recommended for optimal setup. The compact size of the unit (17.63” W x 18.25” H) allows it to fit conveniently in smaller spaces.

While the flow rate is decent, it may struggle to meet the hot water demands of larger households with simultaneous usage in multiple bathrooms or kitchens. The 24 kW power requirement also means that proper electrical infrastructure is necessary; homes must have the right voltage and amperage to support this unit. Additionally, while the warranty coverage is decent, some users may prefer a longer guarantee for peace of mind.

The WINTEMP Electric Tankless Water Heater WN36 is a robust choice for providing endless on-demand hot water for an entire house. With a high power rating of 36 kW, this unit can deliver a substantial flow rate of 3.6 to 8.7 gallons per minute, which is sufficient for simultaneous use across multiple points in a home. It ensures a stable water temperature ranging from 86°F to 140°F, thanks to its self-regulating technology that adjusts energy consumption based on real-time water flow and incoming temperature. This feature not only provides a consistent and comfortable hot water experience but also contributes to its impressive energy efficiency, achieving up to 99% energy savings by reducing power usage when the water flow decreases or when the unit is not in use.

This makes it well-suited for households looking to save on energy costs without compromising on performance. The installation requirements are quite specific and may necessitate professional installation, as it requires 4 x 40 Amp DP breakers, 4 x 8/2 AWG wiring with ground, and a recommended household power supply of 300A. This could be a drawback for some users due to the complexity and potential cost of installation. However, once installed, its compact and wall-mounted design occupies significantly less space compared to traditional tank water heaters, making it ideal for homes with limited space. Safety features such as leakage protection, overheat protection, and dry-fire protection add peace of mind, ensuring safe operation.

Additionally, the inclusion of a digital LED display and Wi-Fi remote control allows for easy temperature adjustments and monitoring. With a high customer rating of 4.6 out of 5 stars, this water heater has proven to be reliable and satisfactory for many users. While it may require a significant initial investment and installation effort, its long-term energy savings, space efficiency, and consistent hot water supply make it a valuable addition to any household.