5 Best Electric Tankless Water Heater for Radiant Heat [In 2025]

In the pursuit of energy efficiency and uninterrupted hot water supply, electric tankless water heaters have emerged as a popular choice for many homeowners. These compact and on-demand systems offer a range of benefits, including space-saving design, cost-saving features, and reliable performance. In this comprehensive review, we’ll explore five top-rated electric tankless water heaters that are well-suited for radiant heat applications.

5 Best Electric Tankless Water Heater for Radiant Heat Reviews

GREATBEAR 14KW On Demand Water Heater Electric 240V

Overview

The GREATBEAR 14KW electric tankless water heater is a powerful and efficient option designed to deliver instant, continuous hot water. With its self-modulating technology and temperature range of 86°F to 131°F, this unit can provide a comfortable and consistent water temperature, even during high-demand scenarios.

Specs

• Power rating: 14kW at 240V
• Flow rate: Up to 5.8 GPM
• Temperature range: 86°F to 131°F
• Dimensions: 15.9″ (H) x 11.1″ (W) x 2.9″ (D)
• Electrical requirements: 60A Double Pole Breaker, 6AWG/2 wires with Grounding

Pros

• Instant and continuous hot water supply
• Self-modulating technology for efficient energy use
• Multiple safety features, including leakage and dry heating protection
• Compact and space-saving design
• Long lifespan of over 10 years

Cons

• Requires a 60A Double Pole Breaker and 6AWG/2 wires for installation
• Some users report issues with water temperature consistency

Customer Reviews

Customers have provided mixed feedback on the GREATBEAR 14KW electric tankless water heater. While some report consistent hot water and efficient performance, others have experienced issues with water temperature fluctuations. The majority of users, however, are satisfied with the unit’s overall functionality and value for money.

ECOTOUCH 9KW 240V On Demand, Self-Modulating Instant Hot Water Heater

Overview

The ECOTOUCH 9KW electric tankless water heater is a self-modulating unit that adjusts its power input based on flow rate and temperature setting. This feature helps ensure a comfortable and consistent water temperature, while also improving energy efficiency.

Specs

• Power rating: 9kW at 240V
• Flow rate: Up to 3.7 GPM
• Temperature range: Up to 116°F
• Dimensions: 11.2″ (W) x 16″ (H) x 3.3″ (D)
• Electrical requirements: 240V

Pros

• Self-modulating technology for efficient energy use
• Instant and endless hot water supply
• Compact and space-saving design
• Multiple safety features, including leakage and overheating protection
• Easy to use with digital display and touch controls

Cons

• Some users report issues with water temperature consistency and lifespan
• May not be suitable for high-demand applications

Customer Reviews

Customers have provided mixed feedback on the ECOTOUCH 9KW electric tankless water heater. While many appreciate its functionality, ease of use, and value for money, some have reported problems with water temperature and the unit’s lifespan. Overall, the majority of users are satisfied with the performance of this self-modulating water heater.

EcoSmart ECO 8 Tankless Water Heater

Overview

The EcoSmart ECO 8 is a compact and efficient electric tankless water heater that is well-suited for climates where the incoming water temperature is 67°F or above. This model is designed to provide hot water for up to 2 gallons per minute, making it a suitable option for low-flow applications.

Specs

• Power rating: 8kW at 240V
• Flow rate: Up to 2 GPM
• Temperature range: Adjustable in 1°F increments
• Dimensions: 12″ (H) x 8″ (W) x 4″ (D)
• Electrical requirements: 240V

Pros

• Compact and space-saving design
• Digital temperature control for precise adjustments
• Suitable for low-flow applications
• Affordable price point

Cons

• May not be suitable for whole-house or high-demand applications
• Some users report issues with water temperature consistency and leaks

Customer Reviews

Customers have provided mixed feedback on the EcoSmart ECO 8 electric tankless water heater. While some users appreciate its compact design, easy installation, and value for money, others have reported issues with water temperature and leaks. Overall, the unit seems to perform well for low-flow applications, but may not be suitable for high-demand scenarios.

MIZUDO 18kW Electric Tankless Water Heater

Overview

The MIZUDO 18kW electric tankless water heater is a powerful and efficient option designed to provide instant hot water for whole-house applications. With a high flow rate of up to 4.2 GPM and a temperature range of 86°F to 140°F, this unit can handle multiple simultaneous water points with ease.

Specs

• Power rating: 18kW at 240V
• Flow rate: Up to 4.2 GPM
• Temperature range: 86°F to 140°F
• Dimensions: 17.05″ (H) x 12.91″ (W) x 3.58″ (D)
• Electrical requirements: 2 x 40A breakers, 2 x 8 AWG wiring

Pros

• High flow rate and temperature range for whole-house applications
• Compact and space-saving design
• Intuitive LED touch display for precise temperature control
• ETL certification and multiple safety features
• Rapid heating technology for near-instant hot water

Cons

• Requires two dedicated 240V circuits and specialized electrical installation
• Limited customer feedback available at the time of writing

Customer Reviews

At the time of writing, there were limited customer reviews available for the MIZUDO 18kW electric tankless water heater. However, the product’s impressive specifications and features suggest it could be a reliable and powerful option for whole-house radiant heat applications, provided the proper electrical installation is in place.

Ranein 18kW 240V On Demand Instant Endless Water Heater

Overview

The Ranein 18kW electric tankless water heater is a high-performance unit designed to deliver instant and endless hot water for whole-house applications. With its 99% thermal efficiency and 4.3 GPM flow rate, this model can handle up to 2-3 household water points simultaneously.

Specs

• Power rating: 18kW at 240V
• Flow rate: Up to 4.3 GPM
• Temperature range: 86°F to 131°F
• Dimensions: 13.8″ (H) x 3.1″ (W) x 18.7″ (D)
• Electrical requirements: 2 x 40A breakers, 2 x 8 AWG wiring

Pros

• Powerful performance with high flow rate and thermal efficiency
• Compact and space-saving design
• Intuitive temperature control with LED display
• CSA certification and multiple safety features
• Rapid heating technology for instant hot water

Cons

• Requires specialized electrical installation with two 240V circuits
• Limited customer feedback available at the time of writing

Customer Reviews

Similar to the MIZUDO model, there were limited customer reviews available for the Ranein 18kW electric tankless water heater at the time of writing. However, the product’s impressive technical specifications and safety features suggest it could be a reliable and high-performing option for whole-house radiant heat applications, provided the proper electrical setup is in place.

Buying Guide: Choosing the Best Electric Tankless Water Heater for Radiant Heat

Factors to Consider

• Power Rating: Ensure the unit has sufficient power (kW) to meet your hot water demands, especially for whole-house applications.
• Flow Rate: Look for a unit with a high flow rate (GPM) to handle multiple simultaneous water points.
• Temperature Range: Consider the temperature range (°F) and adjustability to suit your specific needs.
• Dimensions and Installation: Evaluate the unit’s size and installation requirements to ensure it fits your available space and electrical setup.
• Safety Features: Look for units with certifications and built-in protections for peace of mind.

Pros and Cons of Electric Tankless Water Heaters for Radiant Heat

Pros:

• Instant and continuous hot water supply
• Improved energy efficiency and cost savings
• Compact and space-saving design
• Precise temperature control
• Reduced maintenance requirements

Cons:

• Potentially higher upfront cost
• Specialized electrical installation requirements
• May not be suitable for high-demand applications
• Some models may have issues with water temperature consistency

FAQs

1. What is the difference between a tankless and a traditional tank water heater?

The main difference is that tankless water heaters heat water on demand, eliminating the need for a storage tank. This results in improved energy efficiency and a continuous supply of hot water, as opposed to the limited capacity of a traditional tank heater.

2. How do I determine the right size electric tankless water heater for my home?

The size of the water heater should be based on your expected hot water demand, measured in gallons per minute (GPM). Consider factors like the number of bathrooms, appliances, and simultaneous usage to ensure the unit can meet your needs.

3. What are the electrical requirements for an electric tankless water heater?

Electric tankless water heaters typically require a dedicated 240V circuit and high-amperage breakers (e.g., 40A or higher). The specific electrical requirements will vary by model, so be sure to check the manufacturer’s specifications before purchase and installation.

4. How do I maintain an electric tankless water heater?

Maintenance for electric tankless water heaters is relatively minimal, typically involving periodic cleaning of the heating elements and flushing the system to remove mineral buildup. It’s important to follow the manufacturer’s recommended maintenance schedule to ensure optimal performance and longevity.

5. Can an electric tankless water heater be used for radiant heat systems?

Yes, electric tankless water heaters can be a suitable option for radiant heat systems, provided the unit has sufficient power and flow rate to meet the heating demands of the home. When selecting a model, be sure to consider the size of the radiant heat system and choose a unit with the appropriate specifications.

Conclusion

Electric tankless water heaters offer a range of benefits for homeowners seeking an efficient and reliable hot water solution, particularly for radiant heat applications. The five models reviewed in this article showcase the variety of options available, each with its own unique set of features and performance characteristics. By carefully considering your specific needs and the factors outlined in the buying guide, you can find the best electric tankless water heater to meet your home’s hot water demands and maximize energy savings.