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

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Our Top Picks

#1

Winner

Rheem 18kW 240V Tankless Electric Water Heater, Gray

Rating
9.8
Chosen by1,180
Power (kW)
Temperature Rise

Most important from
1956 reviews

Power (kW)
Cheaper than Home Depot and pulls about 8kW upon use.
Temperature Rise
No need to set the temperature to 145 unless using multiple hot water devices simultaneously.

The Rheem 18kW 240V Tankless Electric Water Heater is an excellent choice for those seeking an efficient hot water solution for their home. One of its standout features is the flow rate of up to 4.4 gallons per minute, which is sufficient for providing hot water to multiple fixtures simultaneously in smaller households. This model is known for its impressive energy efficiency, boasting a 99.8% rating, which can lead to lower utility bills over time.

The external digital thermostatic control with an LED display allows for precise temperature adjustments, ensuring consistent hot water delivery. Its self-modulating technology is another strong point, as it automatically adjusts the power based on your hot water demand, enhancing its efficiency further. Installation is straightforward with bottom 3/4 inch NPT water connections, making it accessible for both professionals and handy homeowners. The durable copper heating elements are also field serviceable, which can save costs on repairs in the long run.

There are a few considerations to keep in mind. While the flow rate is suitable for smaller households, larger homes or families might find it lacking if they require simultaneous hot water use at multiple points. Additionally, as an electric unit, it may not be the best option for users in areas with frequent power outages, as it relies solely on electricity. The warranty and customer support from Rheem are generally strong, which can give peace of mind, but it's always wise to check the specifics based on your location.

Rating
9.8
Chosen by1,180
Power (kW)
Temperature Rise

Most important from
1956 reviews

Power (kW)
Cheaper than Home Depot and pulls about 8kW upon use.
Temperature Rise
No need to set the temperature to 145 unless using multiple hot water devices simultaneously.
#2

Rheem 24kW 240V Tankless Electric Water Heater Bundle With 3/4 IPS LF EXP E2 With PRV Tankles

Rating
9.6
Flow Rate (GPM)
Energy Efficiency
Installation Requirements

Most important from
789 reviews

Flow Rate (GPM)
Quiet in operation and abundant in hot water supply, the heater makes temperature adjustments hassle-free.
Energy Efficiency
Efficient and reliable, this water heater impressed with its ease of installation and effectiveness.
Installation Requirements
The installation was seamless, and the unit operated exactly as intended, providing quick heating in a compact form.

The Rheem 24kW 240V Tankless Electric Water Heater is a solid choice for those seeking an efficient and powerful electric water heating solution. One of its main strengths is the high flow rate of up to 5.9 gallons per minute (GPM), making it suitable for larger households or properties that require simultaneous hot water usage in multiple locations. Its self-modulating power control ensures consistent and continuous hot water, which is a significant advantage for maintaining comfort and efficiency.

The digital temperature display and ON/OFF dial control add convenience, allowing users to easily adjust water temperatures to their liking. Another benefit is its lead-free compliance, meeting all federal and state standards, which is crucial for safety in drinking water components.

However, there are certain aspects to consider before purchasing. The heater requires a 240V power supply and a significant power capacity of 24 kW, which might necessitate electrical upgrades in some homes. Moreover, while the energy efficiency is generally high with tankless systems, consumers should still evaluate their specific energy costs, as the high wattage may impact electricity bills. Installation requirements can also be a consideration, as professional installation might be needed to ensure compliance with local codes and to handle the electric and plumbing connections properly. Additionally, understanding the warranty terms is essential, as these can vary and influence long-term maintenance costs.

For those prioritizing energy efficiency, a consistent hot water supply, and a potentially lower environmental footprint, the Rheem 24kW model is worth considering, especially if your household has high hot water demands.

Rating
9.6
Flow Rate (GPM)
Energy Efficiency
Installation Requirements

Most important from
789 reviews

Flow Rate (GPM)
Quiet in operation and abundant in hot water supply, the heater makes temperature adjustments hassle-free.
Energy Efficiency
Efficient and reliable, this water heater impressed with its ease of installation and effectiveness.
Installation Requirements
The installation was seamless, and the unit operated exactly as intended, providing quick heating in a compact form.
#3

Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray

Rating
9.4
Power (kW)
Energy Efficiency
Installation Requirements

Most important from
789 reviews

Power (kW)
The unit requires significant power, needing three double throw 40 amp breakers and 8 gauge wire.
Energy Efficiency
Switching to this tankless heater resulted in noticeable savings on electricity bills.
Installation Requirements
Proper installation is crucial; ensure you have the right electrical setup to avoid issues.

The Rheem RTEX-24 is a solid choice for those in need of an electric tankless water heater. It boasts a powerful 24kW output, providing a flow rate of up to 5.9 gallons per minute, which is quite impressive for residential use. This means it can supply consistent hot water for multiple fixtures at once, making it ideal for larger households or situations where high demand is common. The self-modulating power feature helps in energy efficiency, ensuring that it uses only the necessary power to meet your hot water needs, with an impressive efficiency rating of 99.8%. This can lead to savings on energy bills over time.

The unit is designed for easy installation, being wall-mounted and suitable for indoor use. Its compact dimensions mean it can fit into smaller spaces without issue. The adjustable digital temperature display and ON/OFF dial control enhance user-friendliness, allowing for precise temperature adjustments.

There are some drawbacks to consider. The installation might require professional help for some users, especially if electrical work is needed to support the heater’s power requirements. Additionally, while the unit is efficient, it may struggle to provide high flow rates if multiple outlets are used simultaneously, depending on the inlet water temperature and desired output temperature.

Rating
9.4
Power (kW)
Energy Efficiency
Installation Requirements

Most important from
789 reviews

Power (kW)
The unit requires significant power, needing three double throw 40 amp breakers and 8 gauge wire.
Energy Efficiency
Switching to this tankless heater resulted in noticeable savings on electricity bills.
Installation Requirements
Proper installation is crucial; ensure you have the right electrical setup to avoid issues.

Buying Guide for the Best Rheem Tankless Electric Hot Water Heaters

Choosing the right tankless electric hot water heater can significantly impact your home's comfort and energy efficiency. Tankless water heaters provide hot water on demand, which means they don't store hot water but heat it as it flows through the unit. This can save energy and provide a continuous supply of hot water. When selecting a tankless electric hot water heater, it's important to consider several key specifications to ensure you get the best fit for your needs.
Flow Rate (GPM)Flow rate, measured in gallons per minute (GPM), indicates how much hot water the unit can produce at a time. This is crucial because it determines whether the heater can meet your household's hot water demands. For example, a flow rate of 2-3 GPM is suitable for a small household with one or two people, while a larger household with multiple bathrooms and appliances running simultaneously might need a flow rate of 6-8 GPM or higher. Assess your household's hot water usage to determine the appropriate flow rate.
Power (kW)The power of a tankless electric water heater is measured in kilowatts (kW) and indicates how much electricity the unit uses to heat water. Higher kW ratings mean the unit can heat water more quickly and handle higher flow rates. For small households or single-point applications, a unit with 10-15 kW might be sufficient. For larger homes or whole-house applications, you might need a unit with 20-30 kW or more. Consider your household size and hot water usage patterns to choose the right power rating.
Temperature RiseTemperature rise refers to the increase in water temperature as it passes through the heater. This is important because it affects how hot the water will be when it reaches your tap. The required temperature rise depends on your incoming water temperature and the desired output temperature. For instance, if your incoming water is 50°F and you want it to be 120°F, you need a temperature rise of 70°F. Ensure the unit you choose can provide the necessary temperature rise for your region and usage.
Energy EfficiencyEnergy efficiency is a measure of how effectively the water heater converts electricity into hot water. Higher efficiency units use less electricity to produce the same amount of hot water, which can save you money on energy bills. Look for units with high energy efficiency ratings, often indicated by a percentage. An efficiency rating of 90% or higher is considered very good. Consider your long-term energy costs and environmental impact when evaluating efficiency.
Installation RequirementsInstallation requirements include the electrical specifications and space needed for the unit. Tankless electric water heaters often require a dedicated circuit and specific voltage, typically 240V. Additionally, they need to be installed in a location with adequate ventilation and access to water lines. Ensure your home's electrical system can support the unit and that you have a suitable installation location. Consulting with a professional installer can help you understand these requirements.
WarrantyThe warranty of a tankless electric water heater covers repairs or replacements if the unit fails within a certain period. A longer warranty can provide peace of mind and protect your investment. Warranties typically range from 5 to 10 years or more. Consider the length and terms of the warranty when choosing a unit, as it can indicate the manufacturer's confidence in their product's durability and reliability.

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