Finding the best electric tankless water heater for whole house use involves balancing power, efficiency, and installation complexity. The Westinghouse 18kW Electric Tankless Water Heater stands out as the overall best due to its reliable performance and WiFi features. For those seeking a high-capacity option, the NOVIEEX 27kW Heater offers impressive flow rates, ideal for larger households. Meanwhile, the Rheem RTEX-24 provides a solid middle ground with a reputable brand name and a good combination of power and value. Every choice involves tradeoffs, such as higher upfront costs versus long-term savings or compact size versus flow capacity. Continue reading for a detailed comparison to find the best fit for your home.
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Key Takeaways
- High wattage models like the NOVIEEX 27kW handle larger households with multiple outlets simultaneously.
- WiFi-enabled options such as Westinghouse and WINTEMP add convenience but often come at a higher price point.
- Flow rate is a critical factor; most units tested are suitable for moderate to large homes with multiple bathrooms.
- Installation complexity varies; models with self-modulating features tend to be easier for DIY setups.
- Tradeoffs between power, efficiency, and cost are evident, so matching your household size and hot water demand is key.
| electric tankless water heater for whole house use | Voltage | Power | Flow Rate | Dimensions |
|---|---|---|---|---|
| 18kW Tankless Water Heater Ele | 240V | 18kW | up to 4.3 GPM | — |
| ORBEK 18kW Tankless Water Heat | 240V | 18kW | 4.17 GPM | 17"H x 13"L x 3.9"W |
| Electric Tankless Water Heater | 240V | 27kW | up to 6.3 GPM | 11.1" W x 19.2" H x 4" D |
| 27kW Electric Tankless Water H | 240 volts | — | 7.4 GPM | — |
| Westinghouse 18kW Electric Tan | 240V | 18kW | 4.2 GPM | 18.7 x 3.94 x 14.17 inches |
| Rheem RTEX-24 24kW 240V Electr | 240V | 24kW | — | — |
More Details on Our Top Picks
18kW Tankless Water Heater Electric 240V, Self-Modulating, Compact, Whole-House Supply, Easy Install
This model stands out for its small footprint and straightforward installation, making it ideal for homes where space is at a premium. Unlike the larger NOVIEEX 27kW unit, it offers a lower flow rate of 4.3 GPM, which may limit its suitability for larger households. Its self-modulating technology ensures energy efficiency, but the limited flow might require careful planning for simultaneous multiple fixtures. Installation is simplified thanks to standard fittings, though a dedicated 240V circuit is a must. Compared with bulkier options, this unit is less capable of supporting high-demand scenarios but excels in compactness and ease of use.
Pros:- Compact size ideal for tight spaces
- Easy to install with standard fittings
- Multiple safety protections included
- Energy-efficient self-modulating technology
Cons:- Requires a dedicated 240V, 40A circuit
- Limited flow rate for high-demand households
- Installation may require professional electrical work
Best for: Apartment dwellers or small households needing reliable hot water without occupying much space
Not ideal for: Large families or homes with high simultaneous hot water needs due to limited flow rate
- Power:18kW
- Voltage:240V
- Flow Rate:up to 4.3 GPM
- Protection Features:Leakage, dry heating, high temp, auto stop
- Installation Type:Point of use
- Fittings:3/4″ NPT
- Circuit Breaker:40A double pole
Our verdict“This unit is perfect for small households or apartments prioritizing space-saving and ease of installation over high flow capacity.”
ORBEK 18kW Tankless Water Heater Electric 240V – On Demand Hot Water Heater, Max 4.17 GPM, Whole House, ETL Certified
Compared to the WINTEMP 27kW, the ORBEK offers a slightly lower flow rate of 4.17 GPM, making it suitable for smaller to medium-sized homes. Its ETL certification and advanced safety features provide peace of mind, but the need for two 240V/40A breakers means installation can be complex for DIYers. It delivers stable temperature control and efficient operation, though it may struggle to support multiple large fixtures at once. The design emphasizes reliability and safety, but households with higher demand should consider higher-capacity models.
Pros:- ETL safety certification
- Stable temperature control
- Suitable for medium-sized homes
- Reliable instant hot water
Cons:- Requires two 240V/40A breakers
- Complex installation for non-professionals
- Flow rate may be insufficient for multiple large fixtures
Best for: Homeowners wanting a certified, reliable whole-house heater with straightforward safety features
Not ideal for: Large households with simultaneous high-flow demands or those seeking easy DIY installation
- Power:18kW
- Voltage:240V
- Flow Rate:4.17 GPM
- Dimensions:17″H x 13″L x 3.9″W
- Water Connections:3/4″ NPT
- Safety Certifications:ETL
Our verdict“This heater suits those prioritizing safety certification and reliable performance for medium household hot water needs.”
Electric Tankless Water Heater WINTEMP 27kW 240V, Whole House On-Demand Instant Hot Water with LED Display and WiFi Control
This unit’s key advantage lies in its WiFi control and LED display, offering remote management and precise temperature adjustments, making it ideal for tech-savvy users. Its 6.3 GPM flow rate surpasses many competitors like the NOVIEEX 27kW, but the increased power requirement (113A) means professional installation is a must. It’s energy-efficient, with up to 99% savings, and supports multiple fixtures, yet its size and electrical demands may limit installation options in some homes. The remote control feature adds convenience, but the high amperage and electrical complexity make it less suitable for DIY installation.
Pros:- WiFi and app control
- High flow rate supporting multiple fixtures
- Energy efficiency up to 99%
- Space-saving wall-mounted design
Cons:- Requires professional electrical setup
- High power demand (113A)
- Size may need adequate wall space
Best for: Tech-oriented homeowners seeking remote control features and energy efficiency for moderate household hot water needs
Not ideal for: Homes with limited electrical capacity or those preferring straightforward DIY installation
- Power:27kW
- Voltage:240V
- Flow Rate:up to 6.3 GPM
- Dimensions:11.1″ W x 19.2″ H x 4″ D
- Water Connection:3/4″ NPT
- Safety Certifications:ETL
Our verdict“Ideal for households wanting remote control capabilities and high flow, provided they can handle its electrical requirements.”
27kW Electric Tankless Water Heater, NOVIEEX 240V, 7.4 GPM, Indoor, Whole House Use
The NOVIEEX 27kW model offers a significantly higher flow rate of 7.4 GPM, making it suitable for large households with multiple simultaneous hot water demands. Its precise temperature control and high energy efficiency (99.8%) help manage high usage without excessive costs. Compared to the Westinghouse 18kW, it provides nearly double the flow capacity, but that comes with a heavier, more complex installation process requiring professional help. The safety protections and compact design make it a strong choice for demanding households, though its size and high power draw may be a barrier for some.
Pros:- High flow rate supports multiple fixtures
- Very precise temperature control with LED display
- High energy efficiency
- Safety protections included
Cons:- Requires professional installation due to high power demand
- Heavy and potentially complex to install
- Size may need significant wall space
Best for: Large families or homes with multiple bathrooms needing high flow and reliable hot water simultaneously
Not ideal for: Small households or apartments where space and electrical capacity are limited
- Power Source:Electric
- Wattage:27 KW
- Voltage:240 volts
- Flow Rate:7.4 GPM
- Maximum Temperature:140 °F
- Mount Type:Wall
- Item Dimensions:14.13″ W x 15.86″ H
Our verdict“This heater is best suited for large households demanding high flow and reliability, with installation handled by professionals.”
Westinghouse 18kW Electric Tankless Whole House Water Heater, 4.2 GPM, 240V, WiFi & Self Modulating
This model combines WiFi control, energy savings, and a decent flow rate of 4.2 GPM, making it suitable for tech-savvy households with moderate hot water needs. Its self-modulating technology helps reduce energy costs, similar to the 18kW Tankless Water Heater B0BBT4ZR9R, but with added smart features. The copper heating elements promote faster heating, and WiFi compatibility allows for voice commands via Alexa or Google Assistant. However, the 4.2 GPM flow limit may restrict simultaneous use of multiple large fixtures, especially in larger homes, and its installation might require a professional due to high amperage (75A).
Pros:- WiFi and voice control compatibility
- Energy-efficient self-modulating technology
- Copper heating elements for faster heat
- Supports multiple fixtures with moderate flow
Cons:- Requires professional installation
- Limited flow rate for large households
- Size may require wall space considerations
Best for: Homeowners seeking smart control and moderate flow for small to medium households
Not ideal for: Large households with high simultaneous demand or homes lacking electrical capacity for WiFi-enabled units
- Power:18kW
- Voltage:240V
- Flow Rate:4.2 GPM
- Temperature Range:86-140℉
- Dimensions:18.7 x 3.94 x 14.17 inches
- Maximum Pressure:120 psi
- Connections:3/4″ NPT
Our verdict“This heater suits users wanting smart features and reliable moderate capacity, best installed by professionals.”
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater
The Rheem RTEX-24 stands out as the best choice for households with high hot water demands thanks to its powerful 24kW output, ensuring continuous hot water supply even during peak usage. Compared with smaller models like the 18kW units, it handles multiple bathrooms simultaneously without noticeable pressure drops, making it ideal for larger families. Its adjustable temperature control from 80-140°F offers precise tuning, but this comes with the tradeoff of requiring a robust electrical system — typically a 200 AMP service — and proper wiring, which increases installation complexity. While the unit’s energy efficiency and space-saving design are appealing, performance is somewhat dependent on groundwater temperature, meaning colder water may reduce output unless more power is supplied. This model makes the most sense for larger households or those with high simultaneous hot water needs who can manage the electrical requirements.
Pros:- Provides continuous hot water for the entire home
- Precise temperature control in 1-degree increments
- Energy-efficient and space-saving design
Cons:- Requires substantial electrical capacity and professional wiring
- Performance varies with groundwater temperature, potentially reducing efficiency in colder climates
Best for: Large families or homes with multiple bathrooms needing constant hot water without sacrificing space
Not ideal for: Small households or apartments with limited electrical capacity, as installing this unit may require significant electrical upgrades
- Model:RTEX-24
- Power:24kW
- Voltage:240V
- Amperage:100A
- Required Breakers:3 x 40 AMP Double Pole
- Household Service:200 AMP recommended
- Temperature Range:80-140°F
Our verdict“This heater is best suited for larger homes where high demand and electrical capacity are manageable, offering reliable, continuous hot water.”
How We Picked
Products were evaluated based on their power output, flow rate, ease of installation, build quality, and smart features. Performance in typical household scenarios, such as simultaneous multiple outlets, was a key criterion. We also considered user reviews and certification standards like ETL to ensure safety and reliability. Devices were ranked to offer a range of options from budget-friendly to premium, addressing different household sizes and preferences. The goal was to identify units that deliver consistent hot water while balancing cost and usability.Factors to Consider When Choosing Best Electric Tankless Water Heater For Whole House Use
Choosing the best electric tankless water heater for your whole house involves understanding several key factors. Not all units are created equal, and what works for one household may not suit another. By considering capacity, installation, efficiency, and additional features, you can select a heater that provides reliable hot water without unnecessary costs or complications. Here are the main factors to evaluate before making your decision.Flow Rate and Power Output
Flow rate determines how much hot water your system can supply at once, expressed in gallons per minute (GPM). For most households, a unit capable of delivering at least 4 GPM is necessary to meet simultaneous demands like showers, sinks, and appliances. Higher wattage models, such as 24kW or 27kW units, generally provide greater flow capacity, making them better suited for larger homes. However, higher power units may require more robust electrical wiring and a dedicated circuit, adding to installation complexity and costs.
Installation Requirements and Space
Electric tankless water heaters vary in size and complexity of installation. Compact models are easier to fit in tight spaces and often appeal to DIY installers. Still, they may lack the capacity needed for larger households. Conversely, higher wattage units like 27kW models demand substantial electrical upgrades, which should be considered during planning. Proper placement near the main water line minimizes heat loss and maximizes efficiency, so evaluate your home’s existing electrical infrastructure and available space before purchasing.
Efficiency and Operating Costs
Tankless heaters are generally more energy-efficient than traditional tanks, but efficiency varies among models. Features like self-modulating technology adjust power consumption based on demand, reducing energy waste. Smart features, such as WiFi control, can help monitor and optimize usage, saving money over time. Be mindful that higher upfront costs for advanced features may be offset by savings on energy bills, especially in larger households with consistent hot water needs.
Durability and Maintenance
Look for units with high-quality build materials and certifications like ETL or UL, which indicate safety and durability. Regular maintenance, such as flushing out mineral deposits, extends the lifespan of your heater—particularly important in areas with hard water. Models with accessible components and clear user instructions simplify upkeep. Choosing a reputable brand can also provide peace of mind regarding long-term reliability and customer support.
Smart Features and User Interface
Smart features like WiFi control and LED displays can enhance convenience, allowing remote temperature adjustments and system monitoring. These features are especially helpful for households with variable hot water demands or those seeking advanced control. However, they often add to the initial cost and may require ongoing software updates or internet connectivity. Consider whether these extras align with your comfort level and budget, or if a straightforward, manual unit suffices.
Frequently Asked Questions
Can I install an electric tankless water heater myself?
Installation depends on your electrical skills and your home’s existing wiring. Many smaller units with lower wattage are suitable for DIY installation if you have experience working with electrical systems. Larger units, especially those over 18kW, often require a dedicated circuit and professional wiring to meet safety standards. Consulting a licensed electrician is recommended to ensure proper setup and compliance with local codes, particularly for high-capacity models.
How do I know if a unit can handle my household’s hot water demand?
Calculate your household’s peak hot water use by adding the flow rates of all fixtures that may operate simultaneously, such as showers, dishwashers, and washing machines. Most units list their maximum GPM, which should meet or exceed this combined demand. Keep in mind that higher wattage units typically support higher flow rates, making them more suitable for larger families. It’s better to select a slightly higher capacity than your current needs to accommodate future demands or unexpected usage spikes.
Are WiFi features worth paying extra for?
WiFi-enabled models offer the convenience of remote temperature adjustments and usage monitoring, which can be beneficial for households with fluctuating hot water needs or those wanting to optimize efficiency. However, these features often come with a higher initial cost and may require ongoing software updates. If you prefer a simple, reliable system without smart controls, a basic model might save money and still meet your household’s needs effectively.
What maintenance does a tankless water heater need?
Regular maintenance primarily involves flushing the unit to prevent mineral buildup, especially in areas with hard water. This process typically takes only a few minutes and can be done annually or more frequently based on water quality. Checking for leaks, inspecting electrical connections, and replacing any worn parts are also recommended to ensure continued performance. Choosing a unit with accessible components can simplify this upkeep and extend its lifespan.
How long does a typical electric tankless water heater last?
With proper maintenance, most electric tankless water heaters last around 20 years. Durability depends on water quality, usage patterns, and installation quality. Investing in a reputable brand with good customer reviews can enhance reliability and lifespan. While initial costs may be higher for premium units, their longer service life and reduced maintenance can provide better value over time.
Conclusion
For households seeking the best overall balance of power, reliability, and features, the Westinghouse 18kW Electric Tankless Water Heater makes a strong choice. If your household demands higher flow rates and larger capacity, the NOVIEEX 27kW suits larger families well. Budget-conscious buyers should consider models like the ORBEK 18kW for solid performance at a lower cost. Tech-savvy households or those wanting remote control will find the WINTEMP 27kW and Westinghouse options appealing. For premium, long-lasting solutions, the Rheem RTEX-24 offers a reputable brand name with good power-to-cost ratio. Ultimately, your choice depends on household size, installation capacity, and desired features.
