If you’re searching for an electric tankless heater, you’re likely looking for a compact, energy-efficient way to heat water on demand. The best overall pick is the Rheem RTEX-24, thanks to its reliable performance and versatile flow rate. For those on a tighter budget, the Westinghouse 11kW offers solid value with WiFi features, while the Rheem 18kW provides higher capacity for larger households. The key tradeoffs in this category often involve balancing flow rate, energy consumption, and cost. Continue reading for a detailed breakdown of these top options—helping you find the perfect fit for your needs.
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Key Takeaways
- Higher wattage models generally offer increased flow rates but come with a higher upfront cost and energy use.
- WiFi-enabled heaters are increasingly common and can add convenience but may introduce additional complexity or points of failure.
- Flow rate capacity varies significantly; choosing a model that matches your household’s hot water demand avoids underperformance.
- Build quality and certification (like ETL) impact durability and safety, especially for continuous use.
- Budget options can work well for small applications, but larger or multi-point setups often require premium models for consistent performance.
| electric tankless heater | Voltage | Power | Flow Rate | Temperature Range |
|---|---|---|---|---|
| 18kW Electric Tankless Water H | 240V | 18kW | — | — |
| 14kW Tankless Electric Water H | 240V | 14kW | 3.38 GPM | 86°F – 140°F |
| 14kW Tankless Electric Water H | 240V | 14kW | — | 86°F to 131°F |
| Rheem 18kW 240V Tankless Elect | 240V | 18kW | up to 4.4 GPM | — |
| 27kW Tankless Electric Water H | 240 volts | — | 6.5 GPM | — |
| Westinghouse 11kW Tankless Wat | 240V | 11kW | 2.6 GPM at 105°F | — |
| Westinghouse 14kW Tankless Ele | 240V | 14 kW | 3.4 GPM | — |
| Rheem RTEX-24 24kW 240V Electr | 240V | 24 kW | 5.9 GPM | 80°F – 140°F |
| Rheem 8kW Multi Fixture Tankle | 240V | 8 kW | up to 1.95 GPM | 80°F – 140°F |
| 18kW Tankless Water Heater Ele | 240V | 18 kW | 4.9 GPM | 77°F to 140°F |
| Rheem 11kW Multi Fixture Tankl | 240V | 11kW | up to 2.68 GPM | 80°F – 140°F |
More Details on Our Top Picks
18kW Electric Tankless Water Heater 240V ETL Certified WiFi
This 18kW model stands out for its robust performance and smart features, making it ideal for small households seeking reliable hot water without the bulk of traditional tanks. Its high efficiency, with up to 99% savings, means lower energy bills, and the WiFi control adds convenience for remote adjustments. Compared with the 14kW units, it offers higher flow capacity, but that comes with a more demanding electrical setup—requiring two 40 Amp breakers and specialized wiring. This makes installation more complex, especially for DIYers. While its maximum flow rate of 4.3 GPM suits small to medium households, larger families might find it limiting during peak demand. It’s compact, space-efficient, and safe, thanks to ETL certification and safety protections. Overall, this unit offers a balance of power, efficiency, and smart control for those upgrading from traditional tanks or smaller tankless options.
Pros:- Provides continuous hot water without preheating delays
- High energy efficiency with up to 99% savings
- Space-saving wall-mounted design
- WiFi control for remote temperature adjustment
Cons:- Requires professional installation and specific electrical setup
- Maximum flow rate may be insufficient for large households
Best for: Small households or singles who want continuous hot water and smart remote control.
Not ideal for: Large families with high simultaneous hot water needs, due to its limited flow rate.
- Power:18kW
- Voltage:240V
- Maximum Hot Water Output:4.3 gallons per minute
- Dimensions:11.1” x 19.2” x 4”
- Water Connection:3/4″ NPT
- Amperage:75A
Our verdict“This unit is perfect for small households seeking energy-efficient, remotely controllable hot water without the complexity of larger systems.”
14kW Tankless Electric Water Heater, On Demand, 240V, 3.38 GPM
Compared with the 18kW models, this 14kW heater offers a more affordable price point and easier electrical requirements, making it appealing for smaller households or those with limited electrical capacity. Its flow rate of 3.38 GPM is suitable for 2-3 points of use, like a bathroom and kitchen sink, and it provides reliable, instant hot water with high thermal efficiency. However, it’s less capable of handling multiple simultaneous outlets, especially in larger households, which makes it a better fit for couples or singles with moderate hot water demands. Its advanced safety features, including leakage and over-temperature protections, add peace of mind. Installation might require a dedicated 240V/60AMP circuit, which can be a barrier for DIY installation. Overall, it balances performance and cost-effectiveness, ideal for small to medium use cases where space and electrical load are considerations.
Pros:- Provides instant, endless hot water for multiple points of use
- High efficiency with up to 60% energy savings
- Compact, space-saving design
- Advanced safety features including leakage and over-temperature protection
Cons:- Requires dedicated 240V/60AMP circuit breaker
- Flow rate may be insufficient for larger households
Best for: Couples or small families needing reliable hot water at a lower price point with moderate flow demands.
Not ideal for: Large households or homes with multiple simultaneous hot water points, due to its limited flow rate.
- 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 is a smart choice for small households seeking reliable, efficient hot water without overloading their electrical system.”
14kW Tankless Electric Water Heater 240V for Sink & Shower, Gray
This 14kW model excels in tight spaces, perfect for under-sink or wall-mounting setups, providing hot water for 1-2 points like a sink or shower. Its energy efficiency (up to 50%) and smart temperature control with LED display make it a practical choice for single or dual-use scenarios. Compared with larger units like the 18kW models, it’s easier to install and requires less electrical load, but that also means it can’t support multiple simultaneous outlets comfortably. The need for a 60-amp circuit breaker might require electrical upgrades, adding complexity. Its compact size and high thermal efficiency make it suitable for small apartments, offices, or renovation projects where space is at a premium. Overall, it delivers reliable hot water for specific points without the bulk of bigger systems.
Pros:- Energy-efficient with up to 50% cost savings
- Compact size suitable for under-sink installation
- Smart temperature control with LED display
- High thermal efficiency
Cons:- Requires a 60-amp electrical circuit, possibly needing upgrades
- Limited to 1-2 points of use at a time
Best for: Apartment dwellers or small space renovations needing hot water at one or two points with minimal electrical upgrades.
Not ideal for: Homes with multiple hot water points or high simultaneous demand, due to its limited capacity.
- 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
- Efficiency:99.8%
Our verdict“This pick suits small spaces needing reliable hot water at one or two points without the complexity of larger units.”
Rheem 18kW 240V Tankless Electric Water Heater, Gray
The Rheem 18kW model offers dependable performance with a focus on durability and precise temperature control, thanks to its digital thermostat and self-modulating technology. Its flow rate of up to 4.4 GPM makes it suitable for medium households, especially when compared to the 14kW units, which may struggle with higher demand. The copper immersion heating elements are built for longevity and ease of field service. However, the limited flow rate might restrict use during peak times for larger families, and professional installation is recommended due to electrical requirements. This unit shines in environments where consistent hot water and straightforward operation are highest priorities, and it offers a more durable, dependable alternative to less established brands.
Pros:- Digital thermostat with LED display for precise control
- Self-modulating technology for efficient power usage
- Durable copper heating elements, field serviceable
- Easy to install with threaded water connections
Cons:- Limited flow rate of 4.4 GPM for large households
- Requires professional installation due to electrical demands
Best for: Households needing dependable performance with moderate hot water demand and a focus on durability.
Not ideal for: Large households or high-demand settings where flow rate is critical, as 4.4 GPM may be restrictive.
- Power:18kW
- Voltage:240V
- Flow Rate:up to 4.4 GPM
- Color:Gray
- Connection Type:bottom 3/4 inch NPT
Our verdict“This heater offers reliable, durable performance ideal for medium-sized homes prioritizing longevity and consistent hot water.”
27kW Tankless Electric Water Heater with WiFi, ETL Certified
This 27kW model is designed for larger households or those with high hot water needs, offering a flow rate of 6.5 GPM and smart WiFi features for remote control. Its self-modulating technology adapts power to demand, increasing energy efficiency despite its high wattage. It surpasses smaller units like the 14kW models in capacity, but that means it requires a significant electrical setup—specifically, a 200 Amp service with three 40 Amp double-pole breakers. The high power consumption could elevate energy bills, especially if usage is frequent or high-volume. The real benefit lies in its ability to deliver hot water reliably across multiple points simultaneously, making it suitable for large families or homes with multiple bathrooms. Yet, the electrical demands make installation more complex and costly.
Pros:- Remote WiFi control and real-time monitoring
- Space-saving wall-mounted design
- Energy-efficient self-modulating technology
- Supports multiple hot water points simultaneously
Cons:- Requires professional installation and a 200 Amp service
- High power consumption could increase operating costs
Best for: Large households or homes with multiple bathrooms seeking reliable, simultaneous hot water with remote management.
Not ideal for: Small households or apartments with limited electrical capacity, due to high power requirements.
- Power Source:Electric/AC
- Wattage:27,000 watts
- Voltage:240 volts
- Flow Rate:6.5 GPM
- Maximum Temperature:140°F
- Installation Requirements:200 Amp service, 3 × 40 Amp breakers
Our verdict“This heater fits large households needing reliable, high-volume hot water with smart control, accepting the electrical complexity involved.”
Westinghouse 11kW Tankless Water Heater Electric 240V, WiFi, ETL, Gray
This Westinghouse 11kW model stands out for its ability to deliver hot water within just 3 seconds, thanks to its instant-on feature. Its integration of WiFi and voice control offers a level of convenience that larger or more complex systems like the Rheem RTEX-24 cannot match. However, its flow rate of 2.6 GPM limits its suitability for larger households or multiple fixtures simultaneously, making it best for single-point applications. The compact, wall-mountable design simplifies installation in tight spaces, and its durable construction with anti-scale technology ensures longevity. Yet, it requires a dedicated 60A double-pole breaker and 8 AWG wiring, which could be a hurdle for DIY installation or retrofit projects. Overall, this heater is ideal for individuals needing quick hot water at a single fixture with smart features.Pros:- Instant hot water delivery in just 3 seconds
- Smart WiFi and voice control compatibility
- Space-saving, wall-mountable design
- Durable with anti-scale technology
Cons:- Flow rate may be insufficient for multiple fixtures
- Requires a dedicated 60A breaker and specific wiring
Best for: Homeowners with a small sink or one bathroom, seeking quick hot water and smart connectivity.
Not ideal for: Large households or multiple fixtures running simultaneously, due to flow rate limitations and power requirements.
- Power:11kW
- Voltage:240V
- Flow Rate:2.6 GPM at 105°F
- Connections:1/2″ NPT
- Certifications:ETL
- Protection Features:Leakage, overheat, dry-fire, over-voltage
Our verdict“Best suited for small-scale applications where quick, smart-controlled hot water is a priority.”
Westinghouse 14kW Tankless Electric Water Heater, 240V, WiFi, Gray
Compared with the 11kW model, the 14kW Westinghouse offers a higher flow rate of 3.4 GPM, making it more suitable for small to medium households. Its smart WiFi control and safety features mirror those of the smaller unit, but it can support multiple fixtures more comfortably. Still, it shares the same power requirement—dedicated 60A double-pole breaker—and its size remains compact for easy wall mounting. Maintenance concerns, such as inlet filter cleaning, are common to all models in this range, but the higher capacity makes it a better fit for families with moderate hot water demands. It’s not ideal for very large households or simultaneous multi-room use, where higher flow rates are needed. This model makes the most sense for users needing more hot water without sacrificing smart features.Pros:- Higher flow rate of 3.4 GPM for multiple fixtures
- Smart WiFi with voice control
- Compact, wall-mountable design
- ETL safety certification
Cons:- Requires a dedicated 60A breaker and specific wiring
- Limited to residential applications
Best for: Small to medium households needing reliable hot water with smart control features.
Not ideal for: Large households or those with high simultaneous hot water needs, due to flow rate limitations.
- Power:14 kW
- Voltage:240V
- Flow Rate:3.4 GPM
- Maximum Temperature:140°F
- Dimensions:9.56″ W x 12.59″ H x 3.28″ D
- Color:Gray
Our verdict“Ideal for small to medium households seeking reliable, connected hot water with moderate flow capacity.”
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater
The Rheem RTEX-24 provides up to 5.9 GPM, making it well-suited for larger households or multiple fixtures. Its digital thermostatic controls enable precise temperature adjustments, which is a step above simpler models like the Rheem 8kW or smaller Westinghouse units. While its higher power draw and specific electrical requirements—professionally installed—may pose a challenge, it compensates with a 5-year leak warranty and a 1-year parts warranty for peace of mind. Compared to the smaller, WiFi-enabled units, the RTEX-24 prioritizes capacity and control, but at the cost of more complex installation. For users with high hot water demand, this model balances energy efficiency with performance, though it’s overkill for single fixture use.Pros:- High flow rate of 5.9 GPM for multiple fixtures
- Digital thermostatic controls for precise temperature setting
- Energy-efficient operation with on-demand heating
- Long warranty coverage
Cons:- Requires specific electrical wiring and breakers
- More complex installation process
Best for: Larger households or homes with multiple bathrooms requiring simultaneous hot water for several fixtures.
Not ideal for: Small households or apartments with low hot water demand, due to its high power consumption and installation complexity.
- Power:24 kW
- Voltage:240V
- Flow Rate:5.9 GPM
- Temperature Range:80°F – 140°F
- Warranty:5-year leak, 1-year parts
Our verdict“Best suited for larger households needing high-capacity hot water with precise temperature control.”
Rheem 8kW Multi Fixture Tankless Electric Water Heater – 240V
This Rheem 8kW model offers a modest flow rate of up to 1.95 GPM, making it suitable for small households or as a supplementary heater. Its compact size and digital temperature controls provide a straightforward solution for single or dual fixture needs. While less powerful than the 14kW units, it excels in energy efficiency and space-saving design, ideal for retrofit projects or secondary applications. Its limited flow rate restricts its use for simultaneous high-demand scenarios, and professional installation is recommended due to specific electrical requirements. Compared to larger models like the Rheem RTEX-24, this heater emphasizes simplicity and compactness over capacity, fitting well in small spaces but not in high-demand homes.Pros:- Space-efficient, compact design
- Digital temperature controls
- Energy-efficient operation
- Suitable for multiple fixture applications when demand is low
Cons:- Limited flow rate of 1.95 GPM
- Requires professional electrical setup
Best for: Small households or as a point-of-use heater for one or two fixtures.
Not ideal for: Homes needing hot water for multiple fixtures at once or larger households with high flow demands.
- Power:8 kW
- Voltage:240V
- Flow Rate:up to 1.95 GPM
- Temperature Range:80°F – 140°F
- Warranty:5-year leak, 1-year parts
Our verdict“A practical choice for small-scale or supplementary hot water needs where space is limited.”
18kW Tankless Water Heater Electric, NOVIEEX 240V 3s Instant Hot Water Heater
The NOVIEEX 18kW heater balances high power output with a compact form, providing up to 4.9 GPM of instant hot water. Its high efficiency and precise digital temperature controls make it a versatile choice for small to medium households with 2-3 fixtures running simultaneously. Unlike the smaller Rheem or Westinghouse models, it requires a substantial 75A circuit, demanding professional installation. This makes it less suitable for DIYers or retrofit projects where electrical capacity is limited. Its flow rate, while sufficient for most residential needs, might fall short for larger families or high-demand scenarios, but it delivers reliable, immediate hot water in a space-efficient package. It is best for users who need a robust, indoor heater without the size of larger systems.Pros:- High power output enables instant hot water
- Compact, space-saving wall-mount design
- Precise digital temperature control
- High efficiency reduces energy costs
Cons:- Requires a 75A circuit and professional installation
- Limited to indoor use
Best for: Small to medium households needing reliable, instant hot water with high power capacity.
Not ideal for: Large households or homes with electrical system limitations, due to high power requirements.
- Power:18 kW
- Voltage:240V
- Flow Rate:4.9 GPM
- Temperature Range:77°F to 140°F
- Efficiency:99.8%
Our verdict“Ideal for medium households seeking high-capacity, instant hot water in a compact form.”
Rheem 11kW Multi Fixture Tankless Electric Water Heater – 240V
This Rheem model distinguishes itself with its slim, space-saving design, making it ideal for installations where space is limited, such as small apartments or RVs. Compared to larger units like the 18kW Rheem, it offers a more energy-efficient operation by heating water only when needed, but its lower flow rate of 2.68 GPM limits its capacity for multiple fixtures simultaneously. While it provides precise temperature control within a moderate range, the need for professional wiring and electrical setup can complicate installation. Unlike some WiFi-enabled models, this unit focuses on core functionality, which keeps costs down but sacrifices smart home features.
This pick makes the most sense for singles or couples with minimal simultaneous hot water needs and restricted space, but it may fall short for larger households or those expecting higher flow rates.
Pros:- Space-efficient, fits into tight areas easily
- Energy-efficient, heats water only on demand
- Offers precise temperature control
Cons:- Requires professional installation due to wiring needs
- Limited flow rate, not suitable for multiple fixtures at once
- Electrical setup might be complex for some installations
Best for: Small households or apartments where space and energy efficiency are priorities
Not ideal for: Large families or homes with multiple bathrooms needing simultaneous hot water supply
- Power:11kW
- Voltage:240V
- Flow Rate:up to 2.68 GPM
- Temperature Range:80°F – 140°F
- Warranty:5-year leak, 1-year parts
- Size:Compact design
Our verdict“This model works best for small households with limited hot water demands and space constraints, but it’s not designed for busy homes with multiple simultaneous users.”
How We Picked
The selection process focused on evaluating performance, usability, build quality, and value. We prioritized models with sufficient flow rates for typical household use, reliable temperature control, and safety certifications. Ease of installation and maintenance were also considered, along with user-friendly features like WiFi connectivity. To ensure meaningful comparisons, products were ranked based on how well they balanced these factors relative to their price and intended use, aiming to highlight options suited for a range of household sizes and budgets.Factors to Consider When Choosing Electric Tankless Heater
Choosing the right electric tankless heater involves weighing several key factors that influence performance, longevity, and overall value. Understanding these considerations can help prevent common pitfalls, like overestimating your hot water needs or selecting a model with incompatible electrical requirements. The following sections outline the most important aspects to keep in mind when selecting a unit, so you can make an informed decision that aligns with your household’s demands.Flow Rate and Capacity
Flow rate determines how much hot water your heater can produce simultaneously, making it a critical factor for larger households or multiple fixtures. An undersized unit might struggle to meet demand during peak times, leading to cold surprises. Conversely, oversizing can waste energy and increase upfront costs. Carefully estimate your household’s maximum simultaneous hot water needs to choose a model with an appropriate flow rate—typically expressed in gallons per minute (GPM).
Wattage and Electrical Requirements
The wattage rating directly affects the heater’s capacity and efficiency. Higher wattage units, such as 18kW or 27kW models, can deliver more hot water but require a robust electrical system—often a 240V circuit with sufficient amperage. If your home’s electrical setup isn’t rated for these demands, upgrading may be necessary. Smaller units, like 8kW or 11kW, are easier to install but may be limited in hot water output, suitable for small applications or single fixtures.
Energy Efficiency and Operating Costs
Electric tankless heaters are generally more energy-efficient than traditional tank models, but efficiency varies based on design and usage. Features like adjustable temperature controls help prevent overheating, reducing energy waste. Consider models with certifications or features that optimize energy use, especially if you plan to operate the heater continuously or for extended periods. Remember, higher wattage units may consume more electricity, impacting your utility bills.
Installation and Space Considerations
These units are compact but still require proper electrical wiring and venting if needed. Ensure your space can accommodate the unit and that installation aligns with local electrical codes. Some models are designed for easy DIY installation, while others might necessitate professional help. Additionally, think about accessibility for maintenance—units placed in tight or hard-to-reach spots can complicate routine checks or repairs.
Price and Long-Term Value
While cheaper models may seem appealing initially, they often compromise on durability, capacity, or features needed for your household. Investing in a higher-quality unit might cost more upfront but can offer better performance and longevity. Consider the total cost of ownership, including potential electrical upgrades, maintenance, and energy savings, to determine the best value over time.
Frequently Asked Questions
Can I install an electric tankless heater myself?
Installation complexity varies depending on the model and your home’s electrical system. Some units are designed for DIY installation, featuring straightforward mounting and wiring instructions. However, many require a dedicated 240V circuit and possibly electrical upgrades, which often necessitate professional installation to ensure safety and compliance with local codes. If you’re not experienced with electrical work, hiring a licensed electrician is strongly recommended to avoid safety hazards and ensure proper operation.
How do I know what flow rate I need?
To determine your required flow rate, list all fixtures that might run simultaneously—such as showers, sinks, and dishwashers—and check their individual GPM ratings. Add these figures together for a maximum estimate. For example, if two showers (about 2.5 GPM each) and a kitchen sink (1.5 GPM) run at once, you’ll need a heater capable of delivering at least 6.5 GPM. Choosing a slightly higher capacity ensures reliable performance during peak demand.
Are WiFi features worth the extra cost?
WiFi-enabled models can offer convenient remote control, temperature adjustments, and usage monitoring, which might save energy and improve comfort. However, they also add complexity and potential points of failure. If you prefer straightforward operation or have limited tech familiarity, a non-WiFi model might be better. For tech enthusiasts or those managing multiple units, the added convenience can justify the extra investment.
What safety features should I look for?
Safety features such as thermal overload protection, leak detection, and certified safety standards (like ETL or CSA) are essential. These features prevent overheating, electrical faults, and potential damage, especially for continuous use. A unit with reliable safety mechanisms provides peace of mind and reduces the risk of accidents or costly repairs, making it a worthwhile consideration even if it costs a bit more upfront.
How often do I need to perform maintenance?
Electric tankless heaters require minimal maintenance compared to traditional tank models. Regularly flushing the unit to remove mineral buildup, especially if you have hard water, prolongs lifespan and maintains efficiency. Checking and cleaning the filter (if present) annually is usually sufficient. Routine inspections of electrical connections and ensuring the unit is free of dust or debris can prevent unexpected failures and keep the heater running smoothly.
Conclusion
For households seeking a reliable all-around performer, the Rheem RTEX-24 offers excellent balance of capacity, features, and durability—making it the best overall choice. Budget-conscious buyers or small households will find the Westinghouse 11kW a smart pick, especially with WiFi. Those with larger demands or looking for premium features should consider the 27kW Tankless Electric Water Heater for higher flow rates and advanced connectivity. Beginners or DIY enthusiasts will appreciate models that are easier to install and maintain, while multi-point setups require units with higher wattage and capacity. Your ideal pick hinges on your household size, budget, and comfort with electrical work—use this guide to match your specific needs with the best available options.
