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

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 Stiebel Eltron Tempra 36 Trend is a solid choice for a whole-house tankless electric water heater, designed to provide continuous hot water without interruption. Its 36 kW power rating and ability to deliver water temperatures from 68°F to 140°F mean it can handle the needs of a typical household well, offering a good flow rate for multiple faucets or showers at once. The heater’s compact size and wall-mounted design help save space, and it doesn’t require venting, which simplifies installation in many homes.

It features energy-saving auto-modulation technology to adjust power use based on demand, contributing to energy efficiency and potentially lowering electric bills. The digital LED display is easy to read and allows precise temperature control, and the heater operates quietly, which is a nice comfort feature. However, it does require a substantial electrical setup—a minimum of 300 amps service at 240 volts—which may mean additional electrical work and cost for some homes.

The unit weighs 22.5 pounds and has solid copper heating elements, which are durable and support consistent performance. Warranty coverage is reassuring, with 7 years against leaks and 3 years for parts, reflecting confidence in its reliability. This heater suits households with high hot water demand and adequate electrical capacity, while those with smaller homes or limited electrical service might find it less practical. Installation should be done by a professional to ensure it meets electrical requirements and functions safely. If continuous, on-demand hot water and energy efficiency are priorities, this model is a dependable option worth considering.

The Stiebel Eltron Tempra 20 Trend is a compact, electric tankless water heater designed to provide continuous, on-demand hot water for a whole house. It delivers a flow rate of about 2.0 gallons per minute, which is usually enough for smaller households or moderate simultaneous use but might be limited if multiple showers or appliances run together. Its temperature range spans from 68°F up to 140°F, giving you good control over water warmth. With a power rating of 19.2 kW and 240V operation, it requires a strong electrical service (at least 125 amps), so installation may need professional assessment to ensure your home’s electrical panel can support it. One standout feature is its energy-saving auto-modulation technology, which adjusts power use based on demand, helping reduce electricity bills. The unit is also praised for silent operation and a clear digital temperature display, adding convenience.

It’s wall-mounted and doesn’t need venting, making it space-friendly and simpler to install in many homes. The 7-year leakage and 3-year parts warranties offer good peace of mind about durability. The relatively modest flow rate might not meet the needs of larger families or homes with high simultaneous hot water demand. Also, the high power requirement means installation could be costly if your electrical system needs upgrading. This heater is well suited for homeowners seeking an efficient, space-saving solution with reliable hot water for everyday use, especially in smaller to medium-sized households.