10 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 Ranein Electric Tankless Water Heater is designed to provide instant and endless hot water for a whole house, making it suitable for residential use. With a power rating of 18 kW and a flow rate of up to 4.3 gallons per minute (GPM), it can effectively supply hot water to 2-3 usage points simultaneously. The unit offers a high energy efficiency of 99%, which helps in reducing heating costs by up to 60% compared to traditional tank-type water heaters.

Additionally, its compact size (13.8" x 18.7") and wall-mounting capability make it space-saving and convenient to install in various locations within the home. The LED temperature display and knob controls allow for easy temperature adjustments in 1°F increments, ranging from 86°F to 131°F, ensuring a stable and precise hot water output. Safety features such as leakage protection, overheating protection, and damp proofing add to the unit's reliability.

However, the installation requires a 240V power supply and two bipolar 40-amp circuit breakers, which might necessitate professional installation. Furthermore, the maximum temperature output of 131°F may not be sufficient for users who prefer extremely hot water. The product is relatively new to the market, first available in September 2023, and is manufactured in China. The package includes a user manual, parts kit, water heater, and installation template. The Ranein Electric Tankless Water Heater is a strong contender for households looking for an energy-efficient and compact water heating solution, provided the installation requirements are met.