Looking for an electric tankless heater? The best models deliver instant hot water while saving space and energy, but they vary widely in power, features, and price. The Rheem RTEX-24 stands out as the overall top pick for its balance of performance and value, while the Westinghouse WiFi model offers smart controls for convenience. Larger homes need higher wattage units, but they often come with higher costs and complexity. Smaller households or point-of-use applications benefit from compact, affordable options. Continue reading for a detailed breakdown of each model’s strengths and tradeoffs.
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Key Takeaways
- Higher wattage units provide greater flow rates suitable for larger households or multiple fixtures.
- WiFi-enabled models add convenience but tend to come at a premium price.
- Compact designs excel for point-of-use applications like sinks or small bathrooms.
- Self-modulating technology helps maintain consistent temperature and improves energy efficiency.
- Budget options often sacrifice flow rate and durability for initial savings.
| electric tankless heater | Voltage | Power | Flow Rate | Dimensions |
|---|---|---|---|---|
| 18kW Electric Tankless Water H | 240V | 18KW | — | 11.1" W x 19.2" H x 4" D |
| ThermoMate 27kW Tankless Elect | 240V | 27kW | 6.6 GPM | 17.09 x 13.15 x 3.15 inches |
| ThermoMate 18kW Electric Tankl | 240V | 18kW | up to 4.4 GPM | 17.12" x 13.12" x 3.12" |
| 14kW Tankless Electric Water H | 240V | 14kW | 3.38 GPM | 14.2"H x 9.5"L x 3.1"W |
| Rheem 11kW Multi Fixture Tankl | 240V | 11kW | up to 2.68 GPM | — |
| Rheem RTEX-06T 6.5kW Point of | 240V | 6.5 kW | — | — |
| Rheem RTEX-24 24kW 240V Electr | 240V | 24kW | 5.9 GPM | — |
| Rheem 18kW 240V Tankless Elect | 240V | 18kW | up to 4.4 GPM | — |
| Westinghouse 14kW Tankless Ele | 240V | 14 kW | 3.4 GPM | — |
| 14kW Tankless Electric Water H | 240V | 14kW | — | 15.87" x 11.14" x 2.87" |
| 27kW Tankless Electric Water H | 240 volts | — | 6.5 GPM | 13" W x 15.9" H |
| 18kW Tankless Water Heater Ele | 240V | 18kW | 4.9 GPM | 11.14" W × 15.86" H × 3.18" D |
More Details on Our Top Picks
18kW Electric Tankless Water Heater 240V WiFi
This 18kW unit stands out for its combination of space-saving design, WiFi control, and reliable safety features, making it ideal for small to medium homes in mild climates. Compared with the 27kW ThermoMate, it offers less power and flow rate but requires a simpler electrical setup, reducing installation complexity. Its ability to deliver continuous hot water without delay is a key advantage, though its maximum flow rate may limit larger households. The WiFi feature adds convenience for remote adjustments, but it demands a stable internet connection. This model balances capacity and ease of use for those upgrading from simpler units, with tradeoffs in maximum flow and electrical requirements for larger homes.
Pros:- Provides continuous hot water without preheating delays
- Energy-efficient with up to 99% savings
- Space-saving wall-mounted design
- Remote WiFi control for easy temperature adjustments
Cons:- Requires professional installation and specific electrical setup
- Maximum flow rate may be insufficient for larger households
Best for: Families in moderate climates needing reliable, remotely controllable hot water for 2-3 bathrooms
Not ideal for: Large households or homes with high simultaneous hot water demand, due to flow rate limitations
- Power:18KW
- Voltage:240V
- Maximum Hot Water Output:4.3 gallons per minute
- Dimensions:11.1″ W x 19.2″ H x 4″ D
- Water Connection:3/4″ NPT
- Amperage:75A
- Wiring Requirements:2 x 40 Amp DP breakers, 2 x 8/2 AWG wiring
- Safety Certifications:ETL
Our verdict“This heater suits small to medium homes in need of reliable, remotely controlled hot water with minimal space requirements.”
ThermoMate 27kW Tankless Electric Water Heater, 6.6 GPM, ETL Certified
The ThermoMate 27kW heater excels by delivering a high flow rate of 6.6 GPM, making it well-suited for homes with multiple bathrooms or simultaneous fixtures, unlike the smaller 14kW model. Its compact size and smart modulation technology ensure consistent temperature and high energy efficiency, but it demands a significant electrical capacity—requiring 150 amps and complex wiring, which might challenge some installations. Compared to the 18kW unit, it offers higher output but at the cost of more demanding electrical infrastructure. This model makes the most sense for larger households where flow rate is a priority, accepting the tradeoff of more intensive electrical work.
Pros:- Provides instant, endless hot water for multiple fixtures
- Space-efficient and wall-mounted
- High thermal efficiency with smart modulation
- Advanced safety features and UL/CSA certification
Cons:- Requires substantial electrical capacity, complicating installation
- Electrical setup may be costly and complex
Best for: Large households or small commercial settings needing high flow rates and reliable performance
Not ideal for: Small apartments or homes with limited electrical capacity, due to high power requirements
- Power:27kW
- Flow Rate:6.6 GPM
- Voltage:240V
- Dimensions:17.09 x 13.15 x 3.15 inches
- Water Connection:3/4″ NPT
- Electrical Requirements:3 x 40 Amp double-pole breakers, 8 AWG copper wires
Our verdict“This heater is best suited for larger homes with high hot water demand, where electrical upgrades are feasible.”
ThermoMate 18kW Electric Tankless Water Heater, On Demand Instant Hot Water, Self-Modulating, Indoor Use
This 18kW unit offers reliable on-demand hot water with a compact, indoor-friendly design that emphasizes energy efficiency through self-modulation technology. It provides up to 4.4 GPM, slightly less than the 27kW model but sufficient for small households or single bathroom use. Its digital temperature control and space-saving profile make it ideal for indoor installation, contrasting with the larger 27kW heater that demands more electrical capacity and space. The tradeoff involves a slightly lower flow rate and the need for a dedicated 80Amp breaker, which might challenge DIY installation. This model makes the most sense for those prioritizing indoor use and space efficiency over maximum flow rate.
Pros:- Provides instant hot water with no wait time
- Energy-efficient self-modulating technology
- Compact wall-mounted design
- Digital temperature display for precision
Cons:- Requires a dedicated 80Amp breaker setup
- Installation may be complex for DIY users
Best for: Small households or apartment dwellers needing reliable indoor hot water with space constraints
Not ideal for: Homes with high simultaneous hot water needs or where electrical capacity is limited
- Power:18kW
- Voltage:240V
- Flow Rate:up to 4.4 GPM
- Maximum Current:76 Amp
- Dimensions:17.12″ x 13.12″ x 3.12″
- Water Connection:3/4″ NPT
Our verdict“This heater is ideal for indoor spaces where space and energy efficiency are key, but flow rate is moderate.”
14kW Tankless Electric Water Heater, On Demand, 240V, 3.38 GPM
The 14kW heater offers a practical solution for small households or point-of-use settings, delivering a steady 3.38 GPM. Its compact size and high efficiency make it suitable for bathrooms or kitchens where demand is moderate. Compared with the 18kW and 27kW units, it has lower power and flow capacity, but its straightforward installation and safety features make it accessible for many homeowners. The flow rate may be limiting for larger households or simultaneous fixtures, but for single or dual points, it provides reliable hot water without excessive electrical demands. It strikes a balance between affordability, size, and performance, with the tradeoff being lower capacity.
Pros:- Provides instant, reliable hot water
- High efficiency with energy savings
- Compact, space-saving design
- Built-in safety features
Cons:- Flow rate may be insufficient for larger households
- Requires a dedicated 240V/60AMP circuit breaker
Best for: Small households or single fixture applications needing affordable, space-saving hot water
Not ideal for: Large households or simultaneous multi-fixture use requiring higher flow rates
- Power:14kW
- Voltage:240V
- Flow Rate:3.38 GPM
- Temperature Range:86°F – 140°F
- Dimensions:14.2″H x 9.5″L x 3.1″W
- Water Connections:1/2″ NPT
Our verdict“This heater suits small-scale applications where space and budget are primary concerns, but it can’t support high simultaneous demand.”
Rheem 11kW Multi Fixture Tankless Electric Water Heater – 240V
This Rheem model provides on-demand hot water for up to two fixtures, making it suitable for small households or point-of-use applications. Its compact design and digital temperature controls make it easy to install and operate, similar to the 14kW heater but with slightly higher power and flow capacity. Compared to the higher-capacity units, it offers a lower flow rate of up to 2.68 GPM, which limits its use in larger households or multiple simultaneous fixtures. While it does not require venting, the electrical setup may require upgrades, much like other models in this roundup. This heater makes sense for those with modest hot water demands who prioritize simplicity and space savings.
Pros:- Space-saving compact design
- Energy-efficient, heats water only as needed
- Digital thermostatic controls
Cons:- Limited flow rate for larger households
- Requires professional electrical setup
Best for: Small households or apartments needing hot water at one or two fixtures
Not ideal for: Homes with higher hot water needs or multiple bathrooms running simultaneously
- Power:11kW
- Voltage:240V
- Flow Rate:up to 2.68 GPM
- Temperature Range:80°F – 140°F
- Warranty:5-year leak, 1-year parts
Our verdict“Ideal for small-scale applications where space and simplicity outweigh high flow demands, but not suited for large households.”
Rheem RTEX-06T 6.5kW Point of Use Electric Tankless Water Heater
This model stands out for its small footprint and energy-efficient operation, making it ideal for single sinks or small appliances. Compared with larger units like the Rheem RTEX-24, it provides limited flow and hot water volume but excels in tight spaces where a full-scale heater isn’t feasible. Its 6.5 kW power rating ensures quick, on-demand hot water but restricts its use to small-scale points like a bathroom sink or RV. The compact size—roughly 90% smaller than traditional heaters—makes installation flexible, yet it requires a 240V circuit, which might not be available everywhere. The tradeoff is that it’s not suitable for whole-house heating or multiple outlets simultaneously. If you need a dedicated, space-saving hot water source for a single fixture, this makes the most sense.
Pros:- Provides endless on-demand hot water for small applications
- Space-saving design, significantly smaller than traditional units
- Highly energy-efficient, heats water only as needed
Cons:- Requires a 240V power supply, which may limit placement
- Limited to small-scale or point-of-use applications
Best for: Homeowners needing a dedicated, space-efficient heater for a single sink or small appliance.
Not ideal for: Large households or multiple outlets where higher flow rates and volume are necessary.
- Power:6.5 kW
- Voltage:240V
- Type:Tankless Electric Water Heater
- Application:Point of Use
Our verdict“This is a solid choice for those needing a compact, energy-efficient heater for a single fixture or small space.”
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater
The Rheem RTEX-24 makes a compelling case for small to medium households, offering up to 5.9 GPM of hot water. Unlike the smaller RTEX-06T, it supports multiple outlets simultaneously, thanks to its higher 24 kW power rating. Its digital thermostatic controls allow precise temperature adjustments, which can prevent scalding and improve comfort. This model is easier to integrate into larger households but comes with a higher upfront cost and requires specific electrical wiring, including a dedicated breaker. Compared to the Westinghouse 14kW model, it offers a higher flow rate but demands a more substantial electrical setup—making it less suitable for renters or those with limited electrical capacity. This makes it ideal for families or homes where multiple fixtures need hot water at once.
Pros:- Supports multiple outlets simultaneously with high flow rate
- Digital controls for accurate temperature setting
- No venting needed, simple installation
Cons:- Requires specific electrical wiring and breaker setup
- Higher initial cost compared to smaller units
Best for: Families or small households needing reliable, multiple outlet hot water without a bulky tank.
Not ideal for: Homes with inadequate electrical capacity or renters who cannot upgrade wiring easily.
- Power:24kW
- Voltage:240V
- Flow Rate:5.9 GPM
- Temperature Range:80°F – 140°F
- Warranty:5-Year Leak, 1-Year Parts
Our verdict“This model suits medium-sized households seeking efficient, multi-point hot water with straightforward installation.”
Rheem 18kW 240V Tankless Electric Water Heater, Gray
Compared with the Rheem RTEX-24, the 18kW model offers a balance between capacity and ease of installation, supporting up to 4.4 GPM of hot water. Its digital thermostat with LED display provides precise control, and the self-modulation feature adjusts power to meet demand efficiently. The copper immersion heating elements promise durability, yet the flow rate might fall short for larger households or multiple simultaneous outlets. It’s a suitable upgrade for those who want more capacity than a point-of-use heater but aren’t ready for the high electrical demand of the larger unit. However, it still requires professional wiring, which could add to installation costs. This model is best for small to medium households where limited hot water needs are expected.
Pros:- Digital thermostat with LED display for precise control
- Self-modulation for energy efficiency
- Durable copper heating elements
Cons:- Limited flow rate of 4.4 GPM may not serve larger households
- Requires professional wiring and breaker setup
Best for: Small to medium households looking for a reliable, easy-to-install heater with moderate flow capacity.
Not ideal for: Large families or homes with multiple simultaneous hot water demands, where higher flow rates are needed.
- Power:18kW
- Voltage:240V
- Flow Rate:up to 4.4 GPM
- Water Connection:bottom 3/4 inch NPT
Our verdict“This model fits small to medium households seeking a dependable, easy-to-install tankless heater with moderate capacity.”
Westinghouse 14kW Tankless Electric Water Heater, 240V, WiFi, Gray
The Westinghouse 14kW unit brings smart technology into tankless water heating, supporting WiFi control compatible with Alexa and Google Home. Its quick 3-second response time makes it ideal for instant hot water needs at a single fixture or small multiple points. Compared to the Rheem 18kW, its flow rate of 3.4 GPM is more limited, but the added smart features elevate convenience and remote control. Its compact wall-mount design saves space and fits well in modern homes seeking automation. The need for a dedicated 60A double-pole breaker may limit installation options for some, and maintenance of inlet filters every six months is necessary for optimal performance. If you prioritize smart home integration and instant response, this model is a compelling choice.
Pros:- Instant hot water in just 3 seconds
- Smart WiFi controls with voice assistant compatibility
- Space-saving wall-mountable design
Cons:- Requires a dedicated 60A double-pole breaker
- Limited flow rate of 3.4 GPM restricts use for multiple outlets
Best for: Tech-savvy homeowners wanting instant, remotely controllable hot water for small households or specific fixtures.
Not ideal for: Large households or those without the electrical capacity for its 60A breaker requirement.
- Power:14 kW
- Voltage:240V
- Flow Rate:3.4 GPM
- Maximum Temperature:140°F
- Certification:ETL
Our verdict“Perfect for small households seeking instant, remotely controlled hot water with smart features.”
14kW Tankless Electric Water Heater 240V for Sink & Shower, Gray
Designed for small-scale hot water needs, this 14kW heater offers a quick response and smart temperature control. Its compact dimensions make installation straightforward, especially for sink or shower applications, similar to the smaller Rheem point-of-use models but with a higher 14kW power rating. Compared to larger units like the Rheem RTEX-24, it is less suited for multiple outlets or high-demand scenarios. The inclusion of safety features such as leakage and overheating protection adds reliability, but the limited temperature range (86°F to 131°F) may not suffice for all users. Its energy-efficient operation makes it appealing for those looking to avoid standby power loss, yet it demands a 60A circuit, which could mean electrical upgrades. It’s an excellent choice for a single fixture or a small point but not for whole-house applications.
Pros:- Energy-efficient operation with no standby power loss
- Instant hot water with high thermal efficiency
- Smart temperature control with LED display
Cons:- Requires a 60A circuit breaker, possibly needing electrical upgrades
- Limited to 1-2 usage points
Best for: Individuals or small households needing instant hot water at one fixture with energy-efficient operation.
Not ideal for: Large households or multiple outlets where higher flow capacity and broader temperature range are needed.
- Power:14kW
- Voltage:240V
- Dimensions:15.87″ x 11.14″ x 2.87″
- Water Connection:1/2″ NPT
- Temperature Range:86°F to 131°F
Our verdict“Ideal for single fixtures seeking quick, energy-efficient hot water with straightforward installation.”
27kW Tankless Electric Water Heater WiFi 240V ETL Certified
This 27kW model stands out for its impressive flow rate of 6.5 GPM, making it suitable for larger households with multiple fixtures running simultaneously. Its integration of smart WiFi control adds a layer of convenience not offered by the 18kW NOVIEEX, allowing for remote temperature adjustments and real-time monitoring. Compared to the NOVIEEX, this heater’s higher wattage supports greater demand, but it comes with the tradeoff of much higher energy consumption and more complex installation requirements. The self-modulating technology enhances energy efficiency, but the need for professional, dedicated electrical wiring can be a barrier for some users. Overall, this heater fits well for those needing robust capacity and smart features, willing to handle the installation complexity and energy costs.
Pros:- High flow rate supports multiple simultaneous water outlets
- Smart WiFi control for remote temperature management
- Space-saving wall-mounted design
- Energy-efficient self-modulating technology
Cons:- Requires professional installation and specific electrical wiring
- High power consumption may increase energy bills
- Installation complexity due to electrical and water connections
Best for: Large families or households with multiple water fixtures that value remote control and high flow capacity
Not ideal for: Small apartments or single-fixture setups where the high power and capacity are unnecessary and may lead to wasted energy
- Power Source:Electric/AC
- Wattage:27,000 watts
- Voltage:240 volts
- Flow Rate:6.5 GPM
- Maximum Temperature:140°F
- Heat Output:27 KW
- Maximum Pressure:150 psi
- Dimensions:13″ W x 15.9″ H
- Weight:21.5 pounds
Our verdict“This model is best suited for larger households that need high capacity and smart features, despite the higher installation and operational costs.”
18kW Tankless Water Heater Electric, NOVIEEX 240V 3s Instant Hot Water Heater, Flow Rate Max 4.9 GPM
The NOVIEEX 18kW heater is a versatile choice for apartments, small homes, or spaces with limited capacity needs. Its flow rate of 4.9 GPM makes it suitable for 2-3 fixtures running at once, which is less than the 27kW model but adequate for many small households. Its compact size and space-efficient wall-mount design make it more accessible for DIY installation compared to larger units like the 27kW heater. While it offers precise temperature control via an LED display, its performance is limited by its lower wattage, making it less suitable for larger households or simultaneous multiple fixtures. The high efficiency of 99.8% can help offset operational costs, but the need for professional electrical setup remains a barrier for some users. This pick makes sense for users who prioritize space, instant hot water, and moderate capacity over maximum flow.
Pros:- High power output enables instant hot water delivery
- Compact, space-saving wall-mount design
- Precise temperature control with LED display
- High efficiency reduces ongoing energy costs
Cons:- Requires professional electrical installation
- Limited to small to medium household use
- Potentially higher initial setup cost for electrical wiring
Best for: Small families, apartment dwellers, or small commercial spaces needing reliable hot water for a few fixtures
Not ideal for: Large households or homes with high simultaneous water demand, where the flow rate and capacity are insufficient
- Power:18kW
- Voltage:240V
- Flow Rate:4.9 GPM
- Dimensions:11.14″ W × 15.86″ H × 3.18″ D
- Water Connection:3/4″ NPT
- Temperature Range:77°F to 140°F
- Efficiency:99.8%
Our verdict“This heater is ideal for those with modest hot water needs who prioritize space efficiency and quick performance, accepting its limited flow rate for smaller households.”
How We Picked
To determine the best electric tankless heaters, I evaluated each product based on performance, build quality, ease of installation, and value. I prioritized models with sufficient wattage to meet typical household needs, especially for simultaneous hot water demands. Usability features like WiFi control, self-modulation, and compact design also played key roles. I compared customer reviews and expert insights to ensure reliability and longevity, ranking units that strike the best balance between cost and capability. The top picks are those that deliver consistent hot water while minimizing energy waste and installation hassle.Factors to Consider When Choosing Electric Tankless Heater
Choosing the right electric tankless heater involves several considerations beyond basic specs. Understanding your household water demand, space constraints, and budget helps narrow down options. The following factors will guide you through the key aspects to consider for a smart purchase.Flow Rate and Power
Flow rate, measured in gallons per minute (GPM), determines how many fixtures can run simultaneously. Larger households or homes with multiple bathrooms need higher wattage units—typically 18kW or more—to ensure sufficient hot water. Conversely, smaller homes or point-of-use applications can opt for units with lower wattage, saving space and money. Always match your water usage patterns with the unit’s capacity to avoid shortages or cold surprises.
Installation and Space
Space considerations are critical—compact models are easier to install in tight spaces like closets or utility rooms. However, higher wattage units may require special electrical wiring and circuit upgrades, increasing installation complexity. Evaluate your home’s electrical capacity beforehand and consider professional help if needed. Proper ventilation and accessibility also influence the best placement for your heater.
Energy Efficiency and Control
Features like self-modulating technology help optimize energy use by adjusting power based on demand, reducing your electricity bill. WiFi-enabled models provide remote control and monitoring, adding convenience but at a higher cost. Think about whether smart features align with your lifestyle and whether they justify the price premium. An efficient unit pays for itself over time through lower operating costs.
Durability and Maintenance
Investing in a durable model with quality components ensures longevity and reduces maintenance costs. Look for units with reputable certifications like ETL, and check reviews for common issues. Regular flushing and inspection extend lifespan, especially if you live in areas with hard water. Balancing initial cost with build quality helps avoid frequent repairs or early replacements.
Price and Value
While budget models may seem attractive initially, they often fall short in performance or longevity. Premium units tend to offer better features, higher durability, and more consistent performance. Consider your long-term needs—spending more upfront can pay off with reliable hot water and lower operating costs. Aim for a model that provides the best value for your specific household size and usage.
Frequently Asked Questions
Can I install an electric tankless heater myself?
Installation complexity varies depending on the unit’s wattage and your home’s electrical system. Smaller, point-of-use models may be suitable for DIY installation if you have basic electrical skills, but higher wattage units often require a dedicated circuit and professional wiring. Consulting a licensed electrician ensures safety and compliance with local codes, especially for units over 18kW. Proper installation not only guarantees performance but also extends the lifespan of your heater.
Will a higher wattage heater save me more energy?
Higher wattage units can heat water faster and handle larger simultaneous demands, but they don’t necessarily consume more energy overall. Self-modulating technology adjusts power use to meet demand, improving efficiency. Oversized units for your household can lead to unnecessary energy use, so sizing correctly is key. Matching the heater’s capacity to your actual needs results in better efficiency and lower utility bills.
Are WiFi-enabled electric tankless heaters worth the extra cost?
Smart models provide remote control, temperature adjustments, and usage monitoring, which add convenience—especially for busy households or those managing multiple fixtures. However, they come at a higher initial price and may require a stable WiFi connection. If you value remote access and data tracking, these features justify the cost; otherwise, simpler models perform reliably without added tech overhead.
What should I consider if I have hard water?
Hard water can cause mineral buildup inside the heater, reducing efficiency and lifespan. Look for models with corrosion-resistant components or consider installing a water softener. Regular maintenance like flushing the unit helps prevent scaling issues. Investing in a durable, high-quality unit is especially wise if your water supply is hard, saving you money on repairs and early replacement.
How do I know if a unit is powerful enough for my household?
Estimate your household’s concurrent hot water usage—think about how many fixtures will run simultaneously. For example, a home with two bathrooms might require a 24kW unit, while a single-point application may only need 10-14kW. Check the flow rate specifications and wattage to ensure the heater can meet your peak demand without running cold. When in doubt, opting for a slightly higher capacity can prevent shortages during busy times.
Conclusion
For larger households or those wanting seamless, simultaneous hot water, the Rheem RTEX-24 offers a reliable balance of power and efficiency. If you seek affordability and simplicity, compact models like the Rheem RTEX-06T or Westinghouse WiFi are excellent choices. Budget-conscious buyers or those installing for a single fixture will find value in smaller units, but should be mindful of flow limitations. Tech-savvy homeowners aiming for convenience might prefer WiFi-enabled models, while professionals or those with specific performance needs should consider higher wattage, durable units. Ultimately, your choice hinges on household size, installation constraints, and budget—match these factors carefully for the best results.
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