Choosing the best electric tankless water heater involves balancing performance, installation complexity, and cost. The Westinghouse 14kW Tankless Electric Water Heater stands out as a reliable overall choice thanks to its smart WiFi features and solid build quality. For higher demand households, the Stiebel Eltron Tempra 29 Plus offers impressive power and efficiency but comes with a higher price tag. Meanwhile, budget-conscious buyers might lean toward the 14kW Tankless Electric Water Heater for Sink & Shower for small-scale use. Each option offers unique tradeoffs between capacity, ease of use, and price. Continue reading for the full breakdown of these models and what to consider before buying.
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Key Takeaways
- Power capacity directly impacts whether a heater can supply hot water for multiple fixtures simultaneously.
- WiFi features on models like Westinghouse enhance control but can add to cost and complexity.
- Higher wattage units are better suited for whole-house use, while lower wattage models are ideal for single sink or shower applications.
- Build quality and material durability vary widely, affecting long-term reliability and maintenance costs.
- Price differences often reflect capacity, features, and brand reputation, making it crucial to match a model to your specific needs.
| electric tankless water heater | Voltage | Power | Flow Rate |
|---|---|---|---|
| 14kW Tankless Electric Water H | 240V | 14kW | — |
| Westinghouse 14kW Tankless Ele | 240V | 14kW | 3.4 GPM |
| Rheem 18kW 240V Tankless Elect | 240V | 18kW | up to 4.4 GPM |
| Rheem RTEX-24 24kW 240V Electr | 240V | 24kW | up to 5.9 GPM |
| Stiebel Eltron Tempra 24 Trend | 240V | 24kW | — |
| 27kW Electric Tankless Water H | 240 volts | 27 KW | 7.4 GPM |
| ThermoMate 27kW Electric Tankl | 240V | 27kW | 6.6 GPM |
| Stiebel Eltron Tempra 29 Plus | 240 volts | — | 3 GPM |
| 18kW Electric Tankless Water H | 240 volts | — | 4.3 GPM |
More Details on Our Top Picks
14kW Tankless Electric Water Heater 240V for Sink & Shower, Gray
This 14kW model stands out for its compact size and high thermal efficiency, making it ideal for under-sink or small wall-mounted installations. Compared with larger models like the Stiebel Eltron Tempra 24 Trend, this unit offers a more space-conscious solution, though it sacrifices some flow capacity. Its energy-efficient operation can save up to 50% on energy bills, which appeals to budget-conscious users, yet it’s limited to 1-2 usage points simultaneously, potentially frustrating households with multiple fixtures. The smart LED temperature control adds convenience, but the requirement for a 60-amp circuit breaker can complicate installation for some. This pick makes the most sense for single-point applications where space and efficiency matter the most, not for whole-house use.
Pros:- Compact size suitable for under-sink or wall-mounted installation
- High thermal efficiency with 99.8% energy efficiency
- Smart LED display for precise temperature control
Cons:- Requires a 60-amp circuit breaker, which might need electrical upgrades
- Limited to 1-2 simultaneous usage points
Best for: Individuals needing a dedicated hot water source for a sink or small shower in tight spaces.
Not ideal for: Large families or households requiring simultaneous hot water at multiple points, due to 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 unit is perfect for small-scale, point-of-use applications where space and efficiency take priority over capacity.”
Westinghouse 14kW Tankless Electric Water Heater, 240V, WiFi, Gray
This Westinghouse model combines a 14kW power output with integrated WiFi and voice control, offering a modern solution for tech-savvy homeowners. Unlike the Rheem 18kW model, it emphasizes smart features and space-saving design, making it suitable for residences that want remote control and monitoring. Its quick hot water delivery—taking just 3 seconds—sets it apart, especially compared to less responsive units. However, it requires a dedicated 60A double-pole breaker, similar to the Rheem 24kW RTEX-24, which may limit its installation options. Its durable, anti-scale technology extends lifespan but necessitates inlet filter maintenance every six months. It’s ideal for those who prioritize convenience and smart home integration, but not for large households with high simultaneous demand.
Pros:- WiFi and voice control compatibility for remote management
- Fast hot water delivery in just 3 seconds
- Space-efficient wall-mount design
Cons:- Requires a dedicated 60A double-pole breaker, which may be hard to install
- Maintenance needed for inlet filters every 6 months
Best for: Homeowners wanting remote operation and smart features for small to medium water demand applications.
Not ideal for: Households with high simultaneous hot water needs or limited electrical capacity, due to breaker requirements.
- Power:14kW
- 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“This model is best for users seeking smart control and quick hot water, suitable for small-scale residential setups.”
Rheem 18kW 240V Tankless Electric Water Heater, Gray
The Rheem 18kW unit offers a higher power capacity with a digital thermostat and LED display, providing precise temperature adjustment—ideal for users who want exact control over hot water settings. Its self-modulation feature ensures efficient energy use by adjusting power based on demand, setting it apart from more basic models like the 14kW Westinghouse. Still, its 4.4 GPM flow rate may fall short for larger households, especially in colder climates that reduce hot water availability. The requirement for a 240V supply limits installation to homes with compatible wiring, which could be a challenge in older structures. This model is suited for small to medium households prioritizing control and efficiency, but not for high-demand environments.
Pros:- Digital thermostat with LED display for accurate temperature setting
- Self-modulation for energy efficiency
- Durable copper heating elements that are field-serviceable
Cons:- Limited flow rate of 4.4 GPM, not ideal for multiple simultaneous fixtures
- Requires existing 240V power supply, which may not be available everywhere
Best for: Homeowners needing precise temperature control and moderate flow capacity for small to medium households.
Not ideal for: Large families or high-demand households where flow rate is critical, due to limited GPM capacity.
- Power:18kW
- Voltage:240V
- Flow Rate:up to 4.4 GPM
- Color:Gray
- Water Connection:bottom 3/4 inch NPT
Our verdict“This unit suits users who want precise control and moderate flow for small to medium homes, with some electrical limitations to consider.”
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater
The Rheem RTEX-24 balances power and size with a 24kW output capable of delivering up to 5.9 GPM, making it a versatile choice for whole-house hot water. Its digital controls allow precise temperature setting between 80°F and 140°F, and its energy-efficient operation heats water only as needed. Compared to the smaller Rheem 18kW model, the RTEX-24 can support multiple fixtures simultaneously, though it still faces limitations in larger households or colder climates. Installation requires three 40-amp double-pole breakers and proper wiring, which might demand professional help. Its space-saving design and no-venting setup make it user-friendly, but the electrical setup requirements could be a barrier for some. This makes it ideal for medium-sized homes with standard electrical capacity, not for very high-demand households.
Pros:- Supports up to 5.9 GPM for multiple fixtures
- Digital temperature control with precise settings
- No venting needed, simplifying installation
Cons:- Requires specific electrical setup (three 40-amp double-pole breakers)
- Flow rate could be insufficient for larger households in cold climates
Best for: Average-sized households seeking a reliable, whole-house hot water solution without venting requirements.
Not ideal for: Large households with high simultaneous hot water needs or limited electrical capacity, due to wiring demands.
- Power:24kW
- Voltage:240V
- Flow Rate:up to 5.9 GPM
- Temperature Range:80°F – 140°F
- Warranty:5-Year Leak, 1-Year Parts
Our verdict“This model provides dependable whole-house hot water with straightforward installation for homes with standard electrical capacity.”
Stiebel Eltron Tempra 24 Trend Electric Tankless Water Heater, 24kW, 240V
The Stiebel Eltron Tempra 24 Trend is designed for consistent, whole-house hot water supply, thanks to its auto-modulation technology that adjusts energy use based on demand. At 24kW, it provides a flow rate sufficient for up to two showers in warm climates, but may struggle in colder conditions where demand increases. Its quiet operation and digital display make it user-friendly, and its high-efficiency auto-modulation minimizes energy waste. The requirement for a substantial 150A service makes it suitable for newer or upgraded homes, but limits its compatibility with older electrical systems. Compared to the Rheem RTEX-24, this unit emphasizes eco-friendliness and continuous flow, making it perfect for eco-conscious households with adequate electrical capacity.
Pros:- Provides continuous, on-demand hot water
- Auto-modulation for energy efficiency
- Quiet operation with digital controls
Cons:- Requires a high minimum electric service of 150A
- Suitable for only up to two showers in colder climates
Best for: Homeowners seeking reliable, on-demand hot water for multiple fixtures in well-electrified homes.
Not ideal for: Homes with limited electrical service or in colder climates with higher simultaneous demand needs.
- Power:24kW
- Voltage:240V
- Recommended Electric Service:150 A
- Temperature Range:68°F to 140°F
Our verdict“This heater excels for eco-conscious homes with ample electrical capacity needing dependable whole-house hot water.”
27kW Electric Tankless Water Heater, NOVIEEX 240V, 7.4 GPM, Indoor Whole House Use
The NOVIEEX 27kW unit stands out for its impressive flow rate of 7.4 GPM, making it well-suited for larger households that need hot water at multiple fixtures simultaneously. Unlike the smaller Stiebel Eltron Tempra 29 Plus, which is more limited in flow, this model supports demanding household needs without sacrificing performance. Its precise temperature control via LED display ensures comfort, while advanced safety features add peace of mind. The main tradeoff is the requirement for professional electrical installation, given its high power draw, and the higher upfront cost compared to traditional tank heaters. For families or homes with high hot water demand, this unit offers reliability and capacity that justify the investment.
Pros:- High flow rate supports multiple simultaneous fixtures
- Precise temperature control with LED display
- Energy-efficient with 99.8% conversion efficiency
- Advanced safety features for reliable operation
Cons:- Requires professional electrical installation due to high power demands
- Heavy and potentially complex for DIY installation
- Higher initial cost compared to traditional tank heaters
Best for: Large households or homes with multiple bathrooms needing simultaneous hot water
Not ideal for: Small apartments or DIY enthusiasts due to complex installation and high power requirements
- Power:27 KW
- Voltage:240 volts
- Flow Rate:7.4 GPM
- Maximum Temperature:140°F
- Dimensions:14.13″ W x 15.86″ H x 3.18″ D
- Water Connections:3/4″ NPT
Our verdict“This unit is best suited for large households that prioritize capacity and energy efficiency, despite the complex installation process.”
ThermoMate 27kW Electric Tankless Water Heater, 6.6 GPM, ETL Certified
The ThermoMate 27kW offers a compact, space-saving design that still delivers up to 6.6 GPM, making it a strong choice for small to medium homes or commercial spaces. Compared with the Stiebel Eltron Tempra 29 Plus, which is more suited for larger households, this model strikes a balance between capacity and installation simplicity. Its smart modulation technology enhances energy efficiency, while safety protections and ETL certification add reliability. The main limitation is its significant electrical requirement of 150 amps, necessitating substantial electrical capacity and professional installation. This pick is ideal for those who need reliable hot water in a smaller footprint but have the electrical capacity in place.
Pros:- Provides instant, continuous hot water for multiple fixtures
- Compact, space-saving design
- High energy efficiency with smart modulation
- Built-in safety protections and ETL certification
Cons:- Requires substantial electrical capacity, possibly needing upgrade
- Professional installation required due to electrical and water connections
- Limited to small to medium-sized spaces
Best for: Small homes, apartments, or commercial spaces needing space-efficient hot water solution
Not ideal for: Large households or homes without sufficient 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
- Weight:16 lbs
- Water Connection:3/4″ NPT
Our verdict“This unit excels for smaller spaces with high hot water needs, provided the electrical system can support it.”
Stiebel Eltron Tempra 29 Plus Electric Tankless Water Heater, 28.8kW, 240V
The Stiebel Eltron Tempra 29 Plus is designed to supply continuous hot water for multiple fixtures, making it ideal for larger homes in warmer regions where cold inlet water is less of an issue. Its sleek, space-saving profile and automatic temperature maintenance add to its appeal. Compared to the NOVIEEX 27kW, which supports higher flow rates, this model offers slightly less but excels in automatic temperature regulation and energy efficiency. Its main drawback is the requirement for dedicated 40 amp breakers and professional wiring, which can complicate installation. It’s a good fit for those seeking reliable, whole-home hot water in moderate climates, where capacity constraints are less critical.
Pros:- Provides continuous hot water for multiple fixtures
- Automatic temperature regulation enhances energy efficiency
- Sleek, space-efficient design requiring no venting
- Adjustable presets for personalized comfort
Cons:- Requires dedicated electrical capacity and professional wiring
- Limited capacity for very high demand or cold climates
- Installation can be complex
Best for: Homes in warm climates needing reliable, continuous hot water with easy temperature control
Not ideal for: Cold climate regions or large households with high simultaneous demand, due to limited flow rate
- Power Source:Hard Wiring
- Wattage:28,800 watts
- Voltage:240 volts
- Flow Rate:3 GPM
- Maximum Pressure:150 psi
- Material Type:Copper
Our verdict“This model suits medium to large homes in warm areas prioritizing automatic temperature control and space efficiency.”
18kW Electric Tankless Water Heater 240V WiFi Certified
The 18kW WiFi-enabled heater offers a practical solution for households needing reliable hot water with modern remote control features. Its flow rate of 4.3 GPM is suitable for typical household needs, similar to the Rheem RTEX-24, but this model adds WiFi connectivity, allowing remote temperature adjustments. Its self-modulating technology improves efficiency, and safety features like leak and overheat protections provide peace of mind. The main limitation is the need for professional installation due to electrical requirements and limited capacity, making it less suitable for larger homes or high-demand scenarios. This heater makes the most sense for tech-savvy users who want smart controls in a space-efficient unit.
Pros:- Provides continuous hot water with a decent flow rate
- Energy-efficient with self-modulating technology
- Compact, wall-mounted design saves space
- WiFi control for remote temperature adjustments
Cons:- Requires professional electrical installation
- Limited capacity for large or high-demand households
- No pricing info available
Best for: Tech-savvy homeowners or small households needing remote control and reliable hot water
Not ideal for: Large households or homes with high simultaneous hot water demands, due to limited flow rate
- Power Source:AC
- Wattage:18,000 watts
- Voltage:240 volts
- Flow Rate:4.3 GPM
- Maximum Temperature:140 °F
- Special Features:WiFi, LED Display
Our verdict“Ideal for small homes or apartments seeking smart, remote-controlled hot water solutions with space efficiency.”
How We Picked
The products in this roundup were evaluated based on their power output, efficiency, usability, build quality, and value for money. Priority was given to models with sufficient wattage to handle typical household demands, along with features like WiFi for remote control. We also considered installation complexity and customer reviews to gauge reliability and ease of use. The ranking reflects how well each unit balances these factors for different types of buyers, from small-scale users to whole-house systems.Factors to Consider When Choosing Best Electric Tankless Water Heater
Choosing the right electric tankless water heater involves understanding several key factors that influence performance, cost, and longevity. Beyond specs, it’s important to consider your household’s hot water demand, the installation environment, and your budget. Making an informed choice can prevent overspending on unnecessary capacity or ending up with insufficient hot water during peak use.Capacity and Power Output
Wattage determines how much hot water a unit can produce simultaneously. Smaller units around 14kW are suitable for single sinks or showers, while higher wattage models like 28-30kW can support whole-house demand. Overestimating capacity leads to unnecessary expense, but undersizing results in inadequate hot water during busy mornings. Match the wattage to your household size and typical hot water needs for optimal performance.
Efficiency and Energy Consumption
Look for models with high energy efficiency ratings to keep operating costs low. Some units feature advanced electronics that modulate power based on demand, reducing waste. However, more efficient models may also include smart features like WiFi, which can be a double-edged sword—adding convenience but increasing upfront cost and complexity. Balance your desire for savings with your comfort level for managing tech features.
Installation and Space Requirements
Electric tankless heaters generally require a dedicated electrical circuit and proper venting depending on size. Compact units are easier to install in tight spaces, making them ideal for small apartments or point-of-use applications. Larger, whole-house units demand more robust wiring and professional installation, which can increase initial costs. Consider your space and technical skills before choosing a model to ensure smooth setup.
Durability and Maintenance
Materials like copper and stainless steel contribute to the longevity of the unit, especially in areas with hard water. Some models include anti-scale features or self-cleaning mechanisms to reduce maintenance. Cheaper units might save money upfront but could require more frequent repairs or replacements. Long-term reliability should weigh heavily in your decision, especially for whole-house systems where downtime is inconvenient.
Price and Value
Pricing varies significantly based on capacity, features, and brand reputation. While budget models can be cost-effective for small-scale use, investing a bit more can provide better reliability, efficiency, and control features. Consider your long-term needs and whether a higher initial investment will save money on repairs and energy bills over time. Always compare the total cost of ownership beyond just the purchase price.
Frequently Asked Questions
Can a small electric tankless water heater supply hot water for multiple fixtures at once?
Generally, small units with lower wattage are designed for single fixtures or small-scale use. They lack the capacity to serve multiple outlets simultaneously, especially in larger households. If you need hot water for several fixtures at once, look for higher wattage models or dedicated whole-house units. Proper sizing is key to avoiding cold shocks during peak demand periods.
Is WiFi connectivity worth paying extra for in an electric tankless water heater?
WiFi features offer convenient remote control and monitoring, which can enhance user experience. However, they also add to the upfront cost and potential points of failure. If you value smart home integration or want to troubleshoot remotely, investing in a WiFi-enabled model makes sense. For basic needs, simpler units without connectivity might be more reliable and cost-effective.
How does water hardness affect the lifespan of an electric tankless water heater?
Hard water can cause mineral buildup inside the unit, reducing efficiency and increasing maintenance needs. Choosing a model with anti-scale features or installing a water softener can extend the lifespan and maintain performance. Otherwise, expect more frequent descaling or repairs over time, which can offset initial savings on a cheaper unit.
What is the typical lifespan of an electric tankless water heater?
Most quality units last around 20 years with proper maintenance. Regular flushing to remove mineral deposits, especially in hard water areas, is crucial for longevity. Cheaper models or those with inferior materials may fail sooner, so investing in a reputable brand with good reviews can pay off over the long run.
Should I choose a higher wattage unit for future expansion plans?
Opting for a higher wattage heater can provide extra capacity if your hot water needs increase later. However, it may also mean higher initial costs and more complex installation. If you anticipate significant household growth or additional fixtures, investing in a more powerful unit now can prevent the need for costly upgrades later. Otherwise, sizing accurately for current needs is typically more economical.
Conclusion
For most households, the Westinghouse 14kW Tankless Electric Water Heater strikes a great balance of performance and affordability, making it the best overall choice. Buyers seeking maximum capacity and efficiency should consider the Stiebel Eltron Tempra 29 Plus as a premium option. Those new to tankless systems or with small demands may prefer the 14kW Tankless Electric Water Heater for Sink & Shower for its simplicity and lower cost. Ultimately, matching your household size, water demand, and budget will guide the best selection for your needs.
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