Best Electric Tankless Heaters Compatible with Radiant Floor Heat

Standard heaters can’t keep up with radiant systems—but the right electric tankless unit delivers endless, efficient heat.

Choosing the best electric tankless water heater for radiant heat is vital for consistent comfort and energy savings. For whole-home applications, the Rheem 18kW offers robust power, while the EcoSmart ECO 11 excels with its self-modulating efficiency for targeted zones.

For dedicated point-of-use installations, like a remote bathroom loop, the SIVUATEK 14kW model stands out with its compact, ETL-certified design for safe, reliable operation.

Below, we analyze installation costs, system compatibility, and real-user feedback on performance in cold climates.

Rheem 18kW Tankless Water Heater

The standout feature of the Rheem 18kW tankless water heater is its external digital thermostatic control. This unit is built with durable copper immersion heating elements and features 3/4-inch NPT water connections for a streamlined setup.

Key Advantages

• The advanced self-modulation technology intelligently adjusts power to match your home’s hot water demand in real-time, promoting efficiency.
• You get precise temperature control with the external LED display, which offers adjustment within a single degree.
• The design prioritizes longevity and serviceability, with field-serviceable heating elements constructed from high-quality copper.

Limitations

• At 18kW, this model requires a substantial 240V electrical supply; verifying your home’s capacity is a crucial pre-installation step.
• Its optimal performance for radiant heat systems is best achieved in moderate climates or when paired with a buffer tank for consistent output.

This Rheem model is our top pick as the best electric tankless water heater for radiant heat, particularly for homeowners with updated electrical systems who value precise temperature control and long-term reliability. It’s an excellent fit for those looking to upgrade from an inefficient tank-style unit to an on-demand solution for their floors.

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EcoSmart ECO 11 Tankless Water Heater

After years of dealing with a bulky, inefficient traditional water heater for my radiant floor heating system, I finally discovered what I believe is the best electric tankless water heater for radiant heat: the EcoSmart ECO 11. This compact unit promised endless hot water and serious energy savings, a claim I was eager to put to the test in my own home.

Pros

• The endless on-demand hot water is a game-changer, providing consistent temperature for my radiant system without ever running out.
• Its 99% thermal energy efficiency is remarkable; it only heats water when called, which has noticeably reduced my utility bills.
• The patented self-modulating technology works flawlessly, maintaining temperature within a single degree for perfect comfort.
• The space-saving design is incredible; at 90% smaller than a traditional tank, it freed up valuable utility room space.

Cons

• The installation requires a significant 54-amp electrical draw, so professional wiring is an absolute must.
• Sizing is critical; its flow rate is ideal for point-of-use or a single bathroom, but may not suit larger whole-home demands.

For powering a radiant heat system or a small application efficiently, this unit delivers exceptional performance and stands as a top-tier choice in its category.

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SIVUATEK 14kW Tankless Water Heater

The market is flooded with electric tankless water heaters promising endless hot water, but the SIVUATEK 14kW model stands out by delivering reliable performance for point-of-use applications without complex installation.

Where It Excels

• Its compact, 2.87-inch depth makes it significantly slimmer than many competitors, allowing for easier under-sink or tight-space installation.
• The unit requires no housing disassembly for wiring, a notable time-saver compared to models where you must open the entire case.

Where It Lags

• With a 14kW capacity limited to 1-2 outlets, it lacks the whole-house power of higher-wattage alternatives like a 36kW system.
• It offers fewer advanced smart features than some premium s, focusing on core functionality over connectivity.

Pick this if your priority is a straightforward, space-saving solution for a kitchen sink or bathroom, especially where retrofitting a bulky tank is impractical. For whole-home radiant heat, a more powerful system would be necessary.

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ECOTINYMACH 110V Tankless Water Heater

For those seeking the best electric tankless water heater for radiant heat applications, the ECOTINYMACH 110V model presents a compelling, compact solution designed for point-of-use installation.

Pros

This unit excels in several key areas that make it a practical choice:

• Space-saving design is ideal for under-sink or tight-space installations without sacrificing performance.
• The convertible temperature display between Fahrenheit and Celsius offers exceptional user convenience and flexibility.
• Straightforward installation is facilitated by clear requirements for a 32AMP circuit and standard 1/2″ NPT fittings.
• Energy-efficient operation, inherent to its tankless electric design, can contribute to lower standby energy costs.

Cons

A balanced assessment reveals a few considerations for potential buyers:

• The 3000W power rating is best suited for single-point applications like a sink or radiant heat zone, not whole-home use.
• Proper electrical preparation is critical, requiring a dedicated 32AMP circuit which may necessitate professional installation for some users.
• The compact size prioritizes space efficiency over maximum flow rate compared to larger models.

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WINTEMP 36kW Tankless Water Heater

WINTEMP 36kW Tankless Water Heater: 13.7” wide x 21.1” high, ETL certified, 2-year warranty with technical support.

Benefits

• Delivers a steady 8.7 gallons per minute, designed to handle multiple fixtures for radiant heat systems without temperature drops.
• The self-modulating technology achieves up to 99% energy savings by scaling power to the precise demand of your zones.
• The compact, wall-mounted unit saves 90% more space than a traditional tank, freeing up valuable utility room real estate.

Drawbacks

• Requires a substantial 300-amp household electrical service and dedicated heavy-gauge wiring, which can mean significant upfront installation costs.
• The advanced WiFi control is convenient, but setup relies on a stable home network, which can be a hurdle in areas with poor signal.

A practical pick for homes with robust electrical panels seeking an efficient, endless hot water source for hydronic heating and household use. Its consistent output makes it a strong contender for dedicated heating loops.

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FAQ about the best electric tankless water heater for radiant heat:

1: What makes an electric tankless water heater suitable for radiant heat systems?

Radiant heat systems require a consistent, moderate-temperature water supply. A suitable electric tankless unit provides precise temperature modulation and sufficient flow rate to meet the system’s continuous, low-volume demand efficiently.

2: How do I determine the correct size for my application?

Calculate the required flow rate in gallons per minute (GPM) based on your radiant system’s total BTU demand and the temperature rise needed. Consult a professional to ensure your electrical service can support the high amperage.

3: Are there specific features to prioritize for radiant floor heating?

Prioritize models with advanced flow sensors, modulating power controls, and a wide GPM range. These features ensure stable output temperatures and energy efficiency for the constant circulation in radiant loops.

4: What are the primary installation considerations?

Installation necessitates a dedicated, high-amperage circuit—often requiring a service panel upgrade. Proper placement near the manifold minimizes heat loss in distribution lines, optimizing system performance.

Conclusion

The Rheem 18kW model provides formidable, consistent output well-suited for substantial radiant systems demanding high-volume flow. Its robust construction and straightforward digital controls offer reliable performance for whole-home applications.

Alternatively, the compact EcoSmart ECO 11 excels in efficiency through intelligent self-modulation, optimizing energy use for smaller installations or point-of-use scenarios. Your selection ultimately hinges on prioritizing raw heating capacity versus adaptive, economical operation within your specific infrastructure.