Finding the best tankless electric water heater depends on your specific needs, whether it’s for a small apartment or a whole house. The Stiebel Eltron Tempra 29 Plus stands out for its high performance and reliability, making it a top overall choice. For those seeking affordability without sacrificing quality, the ThermoMate 14kW Tankless Heater offers excellent value. Meanwhile, the Westinghouse WiFi model provides convenient remote control features. These options illustrate that tradeoffs often involve balancing power, features, and cost. Continue reading for a detailed breakdown of each heater and what makes them suitable for different buyers.
Key Takeaways
- Higher wattage heaters generally support larger households but come with increased upfront costs and installation complexity.
- WiFi-enabled models add convenience but may introduce potential connectivity issues or higher price points.
- Compact units are ideal for small spaces or supplemental water heating, though they might lack the capacity for whole-house use.
- Efficiency and durability are critical, but some models sacrifice features to keep initial costs low.
- Performance consistency varies; the top-rated units deliver steady hot water even during peak demand.
| tankless electric water heater | Voltage | Dimensions | Power | Flow Rate |
|---|---|---|---|---|
| 18kW Tankless Water Heater Ele | 240V | 11.14" W x 15.86" H x 3.18" D | 18kW | 4.9 GPM |
| Stiebel Eltron Tempra 29 Plus | 240 volts | 16.63"W x 14.5"H | — | 3 gpm |
| 14kW Tankless Electric Water H | 240V | 14.2"H x 9.5"L x 3.1"W | 14kW | 3.38 GPM |
| 18kW Tankless Electric Water H | 240V | 15.87" x 11.14" x 2.87" | 18kW | — |
| 18kW Electric Tankless Water H | 240V | 11.1” W x 19.2” H x 4” D | 18kW | — |
| 14kW Tankless Electric Water H | 240V | 15.9 x 11.2 x 3 inches | 14kW | 3.4 GPM |
| Westinghouse 14kW Tankless Ele | 240V | 12.59"H x 9.56"W x 3.28"D | 14kW | up to 3.4 GPM |
More Details on Our Top Picks
18kW Tankless Water Heater Electric NOVIEEX 240V Instant Hot Water Heater, 4.9 GPM, Indoor Use
The NOVIEEX 18kW model stands out for its high flow rate of 4.9 GPM, supporting multiple fixtures simultaneously, making it ideal for small to medium households. Its precise temperature control, with a clear LED display and 1°F adjustments, offers a level of accuracy not always found in similar models like the Stiebel Eltron Tempra 29 Plus. Compared with larger-capacity units, this heater’s compact size and efficiency make it a versatile choice, though it requires a dedicated 75A circuit—something a typical homeowner might struggle to install without professional help. Its high thermal efficiency (99.8%) helps reduce energy costs, but it’s limited to indoor use and cannot handle outdoor conditions. This pick is perfect for those who need reliable, on-demand hot water in smaller living spaces and have access to proper electrical wiring.
Pros:- High flow rate of 4.9 GPM supports multiple fixtures simultaneously
- Precise temperature control with LED display and 1°F adjustment
- Compact, space-saving design ideal for indoor installation
- High thermal efficiency reduces energy costs
Cons:- Requires a dedicated 75A electrical circuit and professional installation
- Limited to small- to medium-sized household use
- No outdoor compatibility
Best for: Small to medium households with up to 3 water fixtures, seeking reliable instant hot water in indoor settings
Not ideal for: Large homes or outdoor use, due to limited capacity and indoor-only design
- Power:18kW
- Voltage:240V
- Flow Rate:4.9 GPM
- Dimensions:11.14″ W x 15.86″ H x 3.18″ D
- Water Connection:3/4″ NPT
- Temperature Range:77°F to 140°F
- Efficiency:99.8%
Our verdict“This model is best for small to medium households that want dependable, precise hot water at a reasonable capacity with space constraints.”
Stiebel Eltron Tempra 29 Plus Electric Tankless Water Heater, 28.8kW, 240V
The Stiebel Eltron Tempra 29 Plus excels with its high power output of 28.8kW, making it well-suited for larger households or scenarios where multiple fixtures demand hot water simultaneously. Its self-modulating technology optimizes energy use, providing savings over less advanced models like the 18kW NOVIEEX, which has a lower flow capacity. This unit’s compact design (16.63″W x 14.5″H) allows for flexible wall mounting, and its German engineering emphasizes durability and efficiency. However, its high wattage and specific wiring needs—40 amp breakers and professional installation—may be a barrier for some homeowners. It’s best in climates where water temperature fluctuations are common, as it maintains consistent output across a wide range of conditions. This makes it an ideal choice for those with higher hot water demands and a more robust electrical setup.
Pros:- Provides continuous hot water for multiple fixtures
- Energy-efficient with up to 34% savings from self-modulating tech
- Compact, space-saving design with German build quality
- Easy to install with no venting needed
Cons:- Requires dedicated 40 amp breakers and professional wiring
- High wattage may not suit homes with limited electrical capacity
- Performance can vary with water temperature and climate
Best for: Larger households or homes with multiple simultaneous hot water needs requiring consistent, high-capacity performance
Not ideal for: Small apartments or homes with limited electrical service, due to high power requirements
- Power Source:Hard Wiring
- Special Features:LED Display
- Wattage:28,800 watts
- Voltage:240 volts
- Flow Rate:3 gpm
- Maximum Pressure:150 psi
- Dimensions:16.63″W x 14.5″H
Our verdict“This unit is best suited for larger households or those needing reliable, high-capacity hot water with efficient energy use, assuming proper electrical infrastructure.”
14kW Tankless Electric Water Heater – On Demand Hot Water – 240V, 3.38 GPM
The 14kW model offers a practical solution for households with modest hot water needs, providing up to 3.38 GPM, making it suitable for small apartments or secondary bathrooms. Its high efficiency and compact size (14.2″H x 9.5″L x 3.1″W) make it easy to install in tight spaces, similar to the 18kW NOVIEEX, but with a slightly lower capacity. The stable temperature control and safety certifications add confidence, though its flow rate may fall short during peak demand or in larger households. Electrical requirements—240V/60AMP circuit breaker—are standard but still necessitate professional wiring. This unit excels for those with limited space who prioritize energy savings and reliable performance for light to moderate use.
Pros:- Provides reliable, instant hot water for essential fixtures
- Compact and space-efficient design
- High energy efficiency with up to 60% savings
- Built-in safety features and stable temperature control
Cons:- Flow rate may be insufficient for larger households
- Requires a dedicated 240V/60AMP circuit—professional installation needed
- Limited capacity for simultaneous use
Best for: Singles or couples with small hot water demands, living in apartments or secondary bathrooms
Not ideal for: Large families or homes with high simultaneous hot water needs, due to 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 model is ideal for small households or secondary applications where space and energy savings are priorities over high flow capacity.”
18kW Tankless Electric Water Heater 240V for Whole House, Gray
The 18kW model aims to serve entire households, providing instant hot water to multiple fixtures with energy-efficient operation. Its design (15.87″ x 11.14″ x 2.87″) is slim, fitting well into various spaces, and its smart temperature control with an LED display enhances usability. Compared to the Stiebel Tempra 29 Plus, it offers similar capacity but with less advanced self-modulation, potentially leading to higher energy consumption in fluctuating conditions. The requirement for two 40-amp circuit breakers might complicate installation for typical homeowners, and it’s suited mainly for homes with moderate water pressure. Overall, this heater balances capacity and efficiency, making it suitable for those wanting a reliable whole-house solution without overly complex features.
Pros:- Provides hot water for multiple points at once
- Energy-efficient with up to 50% cost savings
- Compact, space-saving design with smart controls
- Reliable performance with advanced safety features
Cons:- Requires two 40-amp circuit breakers and professional installation
- Limited to specific water pressure ranges
- Less advanced modulation technology than some premium models
Best for: Homeowners seeking a space-efficient, reliable hot water source for the entire house, with smart temperature control
Not ideal for: Homes with limited electrical capacity or extremely high simultaneous hot water demand
- Power:18kW
- Voltage:240V
- Dimensions:15.87″ x 11.14″ x 2.87″
- Water Connection:3/4″ NPT
- Temperature Range:86°F to 131°F
- Efficiency:99.8%
Our verdict“This unit offers a good balance of capacity and smart control for whole-house hot water needs in homes with adequate electrical infrastructure.”
18kW Electric Tankless Water Heater 240V WiFi
The WiFi-enabled 18kW model combines reliable hot water output (up to 4.3 GPM) with the convenience of remote temperature adjustments. Its compact wall-mounted design makes it ideal for moderate household demands, with self-modulating technology that optimizes energy use. Compared with the Noviex 18kW, it adds modern connectivity, appealing to tech-savvy users who want to control settings remotely. However, it demands a significant electrical upgrade—two 40 Amp double-pole breakers and 8/2 wiring—making installation more complex and requiring a qualified electrician. Its safety protections and 2-year warranty offer peace of mind, but the unit is best suited for homes in mild to moderate climates where extreme temperature fluctuations are less common. This pick is excellent for modern households prioritizing convenience and moderate hot water demands.
Pros:- Provides continuous hot water with no preheating delay
- Remote WiFi control for easy adjustments
- Energy-efficient with self-modulating technology
- Space-saving wall-mounted design
Cons:- Requires a 150 Amp household service for installation
- Installation may need a qualified electrician due to wiring complexity
- Suitable mainly for mild to moderate climate conditions
Best for: Families who want remote control features and moderate hot water needs, with a compatible electrical setup
Not ideal for: Homes with electrical limitations or high simultaneous hot water demands, due to high wiring requirements
- 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
- Certifications:ETL Certified
Our verdict“This model suits tech-savvy households seeking convenient remote control and reliable hot water for moderate use, provided electrical capacity exists.”
14kW Tankless Electric Water Heater, ThermoMate 240V Instant On-Demand Hot Water Heater with Touch Control
The ThermoMate 14kW model stands out for its compact size and energy-efficient operation, making it a top choice for small households, apartments, or cabins. Its smart self-modulating technology ensures consistent water temperature while conserving energy—a clear advantage over less advanced models. Compared with the Westinghouse unit, it offers a slightly lower flow rate but excels in space-saving design. The main tradeoff is its limited capacity—suitable for a few fixtures only—and its reliance on a dedicated 60 Amp circuit, which may require professional installation. Despite this, it provides reliable hot water for smaller setups with minimal footprint, making it ideal for users prioritizing efficiency and space. However, larger households or those with multiple simultaneous demands should consider higher-capacity options.
Pros:- Instant hot water delivery with a flow rate of 3.4 GPM
- Energy-efficient with smart self-modulating technology
- Compact, space-saving design
Cons:- Requires a dedicated 60 Amp circuit breaker and professional wiring
- Limited capacity—best suited for small households or limited fixtures
Best for: Owners of small homes, apartments, or cabins seeking reliable, space-efficient hot water solutions.
Not ideal for: Large families or homes with multiple bathrooms, as its 3.4 GPM flow rate may not meet higher demand.
- Power:14kW
- Voltage:240V
- Flow Rate:3.4 GPM
- Dimensions:15.9 x 11.2 x 3 inches
- Weight:13.2 lbs
- Maximum Temperature:131°F
Our verdict“This model makes the most sense for small households or apartments that prioritize space and energy efficiency over high flow capacity.”
Westinghouse 14kW Tankless Electric Water Heater, 240V, WiFi, ETL Certified, Gray
The Westinghouse 14kW model combines smart WiFi control and safety certifications, making it an excellent choice for homeowners who want integrated tech features and reliable performance. Its ability to deliver hot water in just 3 seconds surpasses many competitors, including the ThermoMate, which offers similar flow rates but lacks WiFi connectivity. The compact, wall-mountable design saves space and simplifies installation, although it still requires a dedicated 60A double-pole breaker and proper wiring. Its safety features, including leakage, overheat, and dry-fire protection, provide peace of mind for residential and light commercial settings. However, maintenance of inlet filters every six months could be inconvenient for some users. Overall, this pick appeals to those who value quick hot water, smart features, and safety certifications.
Pros:- Instant hot water in just 3 seconds
- Smart WiFi compatibility with voice control
- Compact and wall-mountable for space-saving installation
- ETL safety certified
Cons:- Requires a dedicated 60A double-pole breaker and specific wiring
- Maintenance needed for inlet filters every 6 months
Best for: Tech-savvy homeowners or small business operators seeking advanced control and quick hot water delivery.
Not ideal for: Homes with multiple bathrooms or higher simultaneous hot water demands, due to its limited flow rate and capacity.
- Power:14kW
- Voltage:240V
- Connections:1/2″ NPT
- Flow Rate:up to 3.4 GPM
- Dimensions:12.59″H x 9.56″W x 3.28″D
- Certifications:ETL
Our verdict“This unit is ideal for users who want quick, reliable hot water with the convenience of smart control and safety features, especially in smaller setups.”
How We Picked
I evaluated these products based on several key criteria: heating capacity, energy efficiency, build quality, ease of installation, and feature set. Performance under typical household demand was a priority, as was reliability over time. I also considered user interface and maintenance needs, ensuring that each model offers good value for different budgets and use cases. The ranking reflects a balanced assessment of these factors, emphasizing overall performance and versatility while acknowledging tradeoffs like cost and complexity.Factors to Consider When Choosing Best Tankless Electric Water Heaters
Choosing the right tankless electric water heater involves understanding your household’s hot water demands, available space, and budget. Beyond just wattage and flow rate, there are several factors that influence long-term satisfaction and utility. Being aware of these will help you avoid common pitfalls and select a unit that truly fits your needs.Flow Rate and Power
One of the most critical considerations is the heater’s flow rate, measured in gallons per minute (GPM). Larger households or higher simultaneous hot water demands require units with higher wattage and flow capacity, often 18kW or more. Choosing a model with insufficient power can lead to inconsistent water temperature or shortages during peak usage. Conversely, over-specifying can increase upfront costs and installation difficulty without clear benefit for small households or single fixtures.
Energy Efficiency and Operating Costs
Efficiency impacts not only your energy bills but also the environmental footprint of your hot water system. Look for models with good insulation and advanced control features that optimize energy use. Cheaper units may cut corners with build quality, leading to higher maintenance or shorter lifespan. Investing in a slightly more efficient, durable model can save money over years of operation, especially in colder climates where heating demands are higher.
Installation Requirements and Space
Proper installation is essential for safe and reliable operation. Some units require dedicated circuits or specific wiring, which might involve additional electrical work. Compact and wall-mounted designs are advantageous for small spaces or retrofit projects, but verify that your installation area can support the unit’s size and weight. Failing to consider these factors may lead to costly modifications or suboptimal performance.
Features and Control Options
Features like digital displays, remote control, WiFi connectivity, and user presets can enhance convenience and control. However, more advanced features often come at a higher price and may introduce complexity. Decide which features matter most—such as remote monitoring for convenience or advanced safety shut-offs—and balance those needs against your budget and technical comfort level. Overlooking this can result in paying for features you won’t use or difficulty managing the unit.
Cost and Long-Term Value
While initial purchase price is a significant factor, consider the long-term costs of operation, maintenance, and potential repairs. Cheaper models may save money upfront but could require more frequent servicing or replacements. Conversely, investing in a higher-quality, durable unit may yield better reliability and lower total ownership costs over its lifespan. Evaluate warranties and customer support quality as part of your decision-making process.
Frequently Asked Questions
Can a tankless electric water heater support multiple fixtures at once?
The ability of a tankless electric water heater to serve multiple fixtures simultaneously depends on its flow rate and power capacity. Units rated for higher GPM, typically 18kW or above, can tend to handle multiple outlets—such as a shower and sink at the same time—without temperature fluctuations. However, for larger households or simultaneous demands, it’s often better to opt for multiple units or a higher-capacity model to maintain consistent hot water supply and temperature stability.
How difficult is it to install a tankless electric water heater myself?
Installation difficulty varies based on your electrical system and the unit’s requirements. Many models need a dedicated circuit and specific wiring, which might be beyond DIY capabilities for most homeowners. Proper installation is critical for safety and performance, so consulting a licensed electrician is highly recommended. Improper setup can lead to electrical hazards, reduced efficiency, or damage to the unit over time.
Are WiFi-enabled tankless water heaters worth the extra cost?
WiFi-enabled models offer the convenience of remote control, usage monitoring, and sometimes troubleshooting, which can be valuable for tech-savvy users. However, they tend to cost more upfront and may require ongoing connectivity and software updates. If you prioritize smart home integration and remote management, these units are a good choice. For simpler needs or budget-conscious buyers, non-WiFi models still provide reliable performance at a lower price.
What maintenance do tankless electric water heaters require?
Regular maintenance mainly involves flushing the unit to remove mineral buildup, especially in hard water areas. Checking and replacing filters, inspecting electrical connections, and ensuring proper ventilation are also recommended. Many units have self-diagnostic features that alert you to issues, but routine upkeep can extend lifespan and maintain efficiency. Proper maintenance minimizes downtime and costly repairs, making it a worthwhile investment.
How do I choose the right wattage for my household?
Matching wattage to your household’s hot water demand is essential. Smaller households or single fixtures can often suffice with 14kW units, while larger families or simultaneous use require 18kW or higher models. Consider your peak usage times and the number of outlets you need to support. Consulting a professional for load calculations can ensure you select a unit that provides reliable hot water without overpaying for unnecessary capacity.
Conclusion
For most households, the Stiebel Eltron Tempra 29 Plus offers the best balance of power, efficiency, and reliability, making it the ideal choice for those seeking the overall best. Budget-conscious buyers will find excellent value in the ThermoMate 14kW for smaller setups or supplemental heating. Tech-savvy users or larger households might prefer the Westinghouse WiFi model for its remote features and capacity. Beginners or those replacing an old unit should focus on models that are straightforward to install and operate, like the NOVIEEX heater. Ultimately, your choice depends on your specific hot water needs, space constraints, and budget priorities.
