Finding the best electric tankless water heater involves balancing performance, size, and cost. The 36kW Tankless Electric Water Heater stands out as the overall top pick for its high flow rate and WiFi control, making it suitable for busy households. For those prioritizing energy efficiency, the Westinghouse Smart WiFi Model offers smart home compatibility at a competitive price. Buyers often face tradeoffs between capacity, installation complexity, and upfront cost, which can make choosing the right model challenging. Continue reading for a detailed breakdown of the top options and what makes each one unique.
Key Takeaways
- High wattage models like the 36kW heater deliver greater flow rates, ideal for larger households.
- Smart features such as WiFi and voice control are increasingly common, adding convenience but often increasing cost.
- Size and installation complexity vary greatly; compact units suit under-sink use, while larger units are better for whole-home solutions.
- Energy efficiency and certification (like ETL approval) are key factors impacting long-term savings and safety.
- Price ranges reflect differences in capacity, features, and brand reputation; higher upfront cost can mean better durability and tech features.
More Details on Our Top Picks
36kW Tankless Electric Water Heater 240V, Instant On-Demand, Up to 8.7 GPM, WiFi Control, ETL Certified
This 36kW model stands out as the best overall choice for those needing reliable, high-capacity hot water across an entire household. Compared with the Rheem 18kW unit, its significantly higher flow rate of 8.7 GPM handles multiple fixtures simultaneously, making it ideal for larger families. The WiFi control and LED display add convenience for precise temperature management, while its energy-efficient self-regulating technology reduces waste. However, this power comes with the tradeoff of requiring substantial electrical capacity—4 dedicated 40A breakers—and professional installation, which can increase upfront costs. If space and electrical setup aren’t constraints, this model ensures continuous hot water for demanding households.
Pros:- High flow rate of 8.7 GPM handles multiple fixtures simultaneously
- Energy-efficient self-regulating technology reduces operating costs
- WiFi control and LED display for easy temperature adjustments
- Space-saving wall-mounted design
Cons:- Requires significant electrical capacity (4 x 40A breakers)
- Installation complexity and higher initial cost
- Higher upfront investment compared to smaller units
Best for: Large households or homes with multiple simultaneous hot water demands needing maximum flow capacity.
Not ideal for: Small apartments or homes with limited electrical capacity, due to high power requirements and installation complexity.
- Power Source:AC
- Wattage:36 KW
- Voltage:240 Volts
- Flow Rate:8.7 Gallons Per Minute
- Maximum Temperature:140°F
- Efficiency:High Efficiency
- Maximum Pressure:150 PSI
- Special Features:LED Display, Overheat Protection
- Safety Certifications:ETL Certified
Bottom line: This model suits large households seeking maximum hot water output and smart control, provided electrical and space considerations are manageable.
Rheem 18kW 240V Tankless Electric Water Heater, Gray
The Rheem 18kW unit offers a balanced combination of efficiency and control, making it well-suited for smaller households or point-of-use applications. Its digital thermostat with LED display allows exact temperature settings, which is a step up from models without digital controls. Compared to the 36kW model, it has a more modest flow rate of 4.4 GPM, making it ideal for single fixtures or small family use. Its durable copper heating elements and self-modulation technology enhance longevity and efficiency. However, its limited flow capacity and need for a dedicated 240V circuit can be restrictive for larger households or simultaneous multiple uses. It’s a reliable choice for those prioritizing precise control in a smaller footprint.
Pros:- Digital thermostat with LED display for precise temperature control
- Durable copper heating elements
- Self-modulation technology for efficient operation
- Easy installation with threaded connections
Cons:- Limited flow rate of just 4.4 GPM
- Requires dedicated 240V outlet
- Not suitable for high-volume simultaneous use
Best for: Small households or specific point-of-use needs requiring precise temperature control.
Not ideal for: Large families or homes with multiple bathrooms, due to its limited flow rate of 4.4 GPM.
- Power:18kW
- Voltage:240V
- Flow Rate:up to 4.4 GPM
- Heating Elements:Copper immersion
- Control:Digital thermostatic with LED
- Connections:Bottom 3/4 inch NPT
Bottom line: This unit fits small households needing accurate temperature control and space-efficient installation, but isn’t designed for high-demand scenarios.
27kW Electric Tankless Water Heater, 240V On Demand Instant Hot Water with Memory & LED Display, Space-Saving Whole Home System
This 27kW model strikes a solid balance for homes that need more hot water than smaller units but don’t require the capacity of a 36kW system. Its flow rate of up to 6.5 GPM makes it suitable for multiple faucets or showers, especially when space is limited. Features like smart memory and LED display enhance usability, and its energy efficiency of 99.8% helps keep operating costs lower. Installation demands specific electrical capacity—3×40 A breakers and 6 AWG cables—which might challenge some DIYers and increase setup costs. Compared with the 36kW option, it’s a more moderate choice that still offers reliable, on-demand hot water for medium-sized households.
Pros:- Provides up to 6.5 GPM flow rate for multiple fixtures
- Smart control with memory function enhances usability
- Space-efficient design suitable for various installations
- High efficiency of 99.8% reduces operational costs
Cons:- Requires specific electrical setup (3×40 A breakers, 6 AWG cable)
- Installation complexity may deter some DIYers
- Limited temperature range for very hot water needs
Best for: Medium-sized homes or households with moderate hot water demands seeking smart features and space efficiency.
Not ideal for: Large families with high simultaneous hot water needs, due to lower flow rate capacity.
- Power:27kW
- Voltage:240V
- Flow Rate:up to 6.5 GPM
- Dimensions:17.72 x 11.42 x 3.54 inches
- Connections:3/4″ NPT
- Temperature Range:86°F – 140°F
- Efficiency:99.8%
Bottom line: This model is an excellent choice for medium households prioritizing smart controls and space savings, provided electrical requirements are met.
14kW Tankless Electric Water Heater with Digital Display, 240V, Up to 3.38 GPM, ETL Certified
This 14kW heater stands out for its space-saving design, making it an excellent choice for apartments or small homes where space is limited. Compared with larger units like the WINTEMP 27kW, it offers a lower flow rate but easier installation. Its digital display allows precise temperature control, while advanced safety features provide peace of mind. The main tradeoff is its flow rate, which may be insufficient for larger households or simultaneous multiple fixtures. It requires a dedicated 240V/60AMP circuit, which could be complex for some DIY installers. Overall, this pick makes the most sense for singles or couples with occasional need for hot water at one or two points.Pros:- Compact size fits small spaces easily
- Energy-efficient and reduces electricity bills
- Digital LED display for easy temperature control
- Advanced safety protections ensure reliability
Cons:- Flow rate may be too low for multi-showers or large households
- Installation can be complex for non-experts
Best for: Small households or apartments needing reliable hot water at one or two points of use.
Not ideal for: Larger families or homes with high simultaneous hot water demand, due to its limited flow rate.
- Power:14kW
- Voltage:240V
- Flow Rate:Up to 3.38 GPM
- Temperature Range:86°F – 140°F
- Dimensions:14.2″ H x 9.5″ L x 3.1″ W
- Certifications:ETL
Bottom line: Best suited for small households seeking space-efficient, reliable hot water with straightforward controls.
Westinghouse 14kW 240V Smart WiFi Tankless Water Heater Electric, Compatible with Alexa & Google Home, ETL Certified, IPX4, Gray – Upgrade (APOLO-2.0)
The Westinghouse APOLO-2.0 combines a compact footprint with smart home connectivity, making it ideal for tech enthusiasts who want remote control and automation. Compared to the 14kW basic model, its Wi-Fi and voice control add convenience, especially for adjusting settings without manual access. Its flow rate of up to 3.38 GPM suits small to medium households, but might fall short for high-demand scenarios. The unit’s safety features and waterproof IPX4 rating add peace of mind, although professional installation is recommended due to its 60A electrical requirements. This makes it perfect for users wanting modern, connected solutions without sacrificing reliability.Pros:- Wireless control compatible with Alexa & Google Home
- Space-efficient, suitable for tight spaces
- Multiple safety protections including leakage and overheat
Cons:- Flow rate may not support multiple fixtures simultaneously
- Requires professional installation with 60A breaker
Best for: Homeowners who prioritize smart home integration and remote hot water control.
Not ideal for: Large households with simultaneous high-flow needs or limited electrical capacity.
- Power:14kW
- Voltage:240V
- Flow Rate:Up to 3.38 GPM
- Activation Flow:0.5 GPM
- Protection Features:Leakage, overheat, dry-fire, high voltage
- Certifications:ETL
Bottom line: This model is best for users wanting integrated smart home features in a reliable, space-saving unit.
WINTEMP 27kW 240V Electric Tankless Water Heater with WiFi Control
The WINTEMP 27kW unit provides a significantly higher flow rate of up to 6.3 GPM, making it a strong choice for larger homes with multiple fixtures running simultaneously. Compared to the 14kW models, it handles higher demand but requires a much more robust electrical setup—likely a 60A breaker and substantial wiring—adding complexity and cost to installation. Its WiFi control ensures you can manage temperature remotely, which is a convenience for busy households. The main tradeoff is installation difficulty and cost, which makes it less suitable for DIYers or small homes. This unit makes the most sense for families seeking whole-home hot water without sacrificing flow rate.Pros:- High maximum flow rate supports multiple fixtures
- Remote WiFi control allows easy adjustments
- Energy-efficient with up to 99% savings
Cons:- Requires significant electrical wiring and professional installation
- Higher upfront cost due to power needs
Best for: Larger households with high hot water demand and the ability to support robust electrical wiring.
Not ideal for: Small apartments or homes with limited electrical capacity, due to high power requirements.
- Power:27kW
- Voltage:240V
- Flow Rate:Up to 6.3 GPM
- Dimensions:11.1″ W x 19.1″ H x 4″ D
- Water Connection:3/4″ NPT
- Certifications:ETL
Bottom line: Best for large homes needing high flow with smart control, provided electrical capacity is sufficient.
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater
The Rheem RTEX-24 stands out for delivering continuous hot water across larger households, making it a top choice despite its demanding electrical requirements. Compared with smaller units like the 110V under-sink model, it offers significantly higher capacity, suitable for multiple outlets simultaneously. Its adjustable temperature control and digital display make it easy to fine-tune comfort levels. However, its need for a substantial electrical setup—specifically three double-pole 40A breakers—means installation can be complex and costly, often requiring a professional. Performance depends heavily on your home’s ground temperature and electrical panel capacity, so it’s best suited for homes with ample electrical service. Overall, this pick makes the most sense for homeowners seeking reliable, whole-house hot water with the right electrical infrastructure.
Pros:- Provides continuous hot water for entire home use
- Adjustable temperature with a clear digital display
- Space-saving, energy-efficient design
Cons:- Requires significant electrical capacity and professional setup
- Performance varies with groundwater temperature and location
Best for: Families or households with high hot water demand that have a robust electrical system in place.
Not ideal for: Small apartments or rentals with limited electrical capacity, as the installation cost and complexity may outweigh benefits.
- Model:RTEX-24
- Power:24 kW
- Voltage:240V
- Amperage:100A
- Electrical Requirements:3 x 40 AMP Double Pole Breakers, 200 AMP household service recommended
- Temperature Range:80-140°F
Bottom line: Ideal for larger households with strong electrical infrastructure needing reliable, whole-home hot water.
Tankless Electric Water Heater 110V, 3000W, Digital Display, Under Sink Instant Hot Water Heater
This compact unit excels at providing instant, continuous hot water for kitchen or bathroom sinks, making it a practical choice for apartments, RVs, or small homes. Unlike the Rheem RTEX-24, it does not require a large electrical setup—just a standard 110V outlet—so installation is straightforward and affordable. The digital LED display helps monitor temperature easily, and its safety protections add peace of mind. Its flow rate, however, caps at around 0.3-0.5 GPM, which means it isn’t suitable for shower use or high-demand fixtures. Its vertical-only installation limits flexibility, but for small-scale hot water needs, it offers quick, reliable performance without the need for extensive electrical upgrades. This makes it a smart choice for those prioritizing convenience and space-saving design.
Pros:- Provides instant hot water without preheating
- Compact, space-efficient, and stylish design
- Multiple safety protections for reliable operation
- Easy to install with standard fittings
Cons:- Not suitable for shower use due to flow rate limitations
- Requires vertical installation only
- Flow rate may affect temperature consistency
Best for: Single fixtures or small-scale hot water needs in apartments or RVs, especially where electrical capacity is limited.
Not ideal for: Whole-home applications or showers, since its flow rate and capacity are too limited for high-volume use.
- Power:3000W
- Voltage:110V
- Maximum Temperature:122°F
- Flow Rate:0.3-0.5 GPM
- Material:ABS, Brass, Stainless Steel
- Waterproof Rating:IPX4
Bottom line: Best suited for small-scale, point-of-use hot water in compact spaces where electrical simplicity and instant performance matter most.
How We Picked
Our evaluation focused on performance, ease of installation, build quality, and feature set. We prioritized models with sufficient wattage to handle typical household demands, especially those with higher flow rates. Usability features such as digital displays, WiFi control, and compatibility with smart home systems were also key factors. Maintenance requirements and safety certifications helped us gauge long-term reliability. The rankings reflect a balance of value, versatility, and advanced features, ensuring options for different budgets and needs.
Factors to Consider When Choosing Best Tankless Water Heater Electric
Choosing the best electric tankless water heater requires understanding several critical factors. While price is obvious, other elements like capacity, installation complexity, and smart features significantly influence long-term satisfaction. Avoid models that are underpowered for your household’s demand, as they can lead to inconsistent hot water. Conversely, overspending on capacity you won’t use can waste money. Knowing what to prioritize ensures you select a unit that fits both your budget and household needs.
Capacity and Flow Rate
Flow rate, measured in gallons per minute (GPM), indicates how much hot water a unit can deliver at once. For larger households or simultaneous use (shower plus dishwasher), opt for higher GPM ratings—typically above 8 GPM. Smaller homes or under-sink models might do well with 3-4 GPM units. Choosing the right capacity prevents cold surprises during peak usage, making this the most critical factor in satisfying household demands.
Wattage and Power Requirements
Most electric tankless water heaters operate within 18kW to 36kW. Higher wattage units offer greater output but require more robust electrical systems, potentially increasing installation costs. Before buying, verify your home’s electrical capacity to handle the load safely. Underpowered models will struggle to provide consistent hot water, especially in colder climates or larger homes. Matching wattage with your household’s demand is vital for reliable performance.
Smart Features and Connectivity
Many modern units now include WiFi or app control, offering remote temperature adjustments and usage monitoring. These features can enhance convenience and help optimize energy use. However, they often come at a higher price and may require compatible smart home systems. Consider whether smart capabilities are worth the extra investment for your lifestyle, or if a straightforward model suffices. Overloading with features can also introduce complexity or reliability issues.
Installation and Size
Size and ease of installation vary greatly. Compact units designed for under-sink use are simple to install and require less space. Whole-home models need more extensive electrical wiring and possibly professional upgrades, increasing costs. Assess your available space and technical comfort level. Incorrect installation can impair performance or void warranties, so consider professional help if needed.
Cost and Energy Efficiency
While higher-capacity models cost more upfront, they can save money through improved efficiency and durability. Look for units with certifications like ETL, which indicate safety and efficiency standards. Long-term savings depend on proper sizing and installation, so avoid overspending on features you won’t use. Consider the balance between initial investment and ongoing energy costs to find a model that offers real value.
Frequently Asked Questions
Can a smaller electric tankless heater meet my household’s hot water needs?
Smaller units, typically under 4 GPM, are suitable for single-point applications like under-sink use or small apartments. They may struggle to supply hot water for multiple fixtures simultaneously in a larger home. To ensure adequate performance, calculate your household’s peak demand and choose a model with a higher flow rate if needed. Otherwise, you risk cold water during busy mornings or when multiple appliances run at once.
Is it worth paying more for a WiFi-enabled electric tankless water heater?
Smart features can add convenience, allowing remote control and monitoring, which is beneficial for busy households or those interested in energy management. However, these models tend to be more expensive and can be more complex to troubleshoot if issues arise. If you value automation and remote access, investing in a WiFi-enabled unit makes sense; otherwise, a basic model with manual controls may be more straightforward and cost-effective.
What are common installation challenges with electric tankless water heaters?
Most notably, high-wattage units require a dedicated electrical circuit, often demanding upgrades to your home’s wiring or electrical panel. Space constraints can also pose issues, especially for whole-home models. Professional installation ensures safety and performance but can add to the overall cost. Checking your electrical system’s capacity and available space beforehand helps prevent surprises during setup.
How does climate affect the performance of an electric tankless water heater?
Colder incoming water temperatures decrease the heater’s efficiency and flow rate, especially in colder climates. Larger or higher wattage units can compensate by providing more heating power, but they may also cost more upfront. If you live in a cold region, prioritize models with higher capacity and consider additional insulation or pre-heating solutions to maintain consistent hot water supply.
Are there safety concerns with electric tankless water heaters?
Yes, safety certifications like ETL indicate the unit has passed safety standards. Proper installation is critical to prevent electrical hazards, especially given the high power levels involved. Regular maintenance and inspections help ensure safe operation over time. Avoid DIY installation unless you have electrical expertise, as improper setup can pose risks to your home and household members.
Conclusion
For most households, the 36kW Tankless Electric Water Heater offers the best overall performance, especially if you need high flow rates and advanced features. Budget-conscious buyers or those with smaller demands might prefer the 14kW or 18kW models for their affordability and simplicity. Tech enthusiasts seeking smart home integration should consider models like the Westinghouse WiFi heater. Beginners and those upgrading from traditional systems will benefit from models with straightforward installation and easy controls. Ultimately, matching your household size, electrical capacity, and feature preferences will help you find the perfect fit.
