Finding the best tankless water heater depends on your household needs, budget, and energy preferences. The top pick for overall performance is the Rinnai RX199iN, known for its high flow rate and smart features. For a budget-friendly option, the EcoSmart ECO 11 offers reliable efficiency at a lower cost, while the Rheem Performance RTEX-11 balances price and performance for most homes. Buyers face tradeoffs between capacity, energy efficiency, and upfront costs, making it essential to choose wisely. Continue reading for a detailed comparison of these models and more to find your ideal tankless water heater.
Key Takeaways
- High flow rate models like the Rinnai RX199iN excel in larger households with high hot water demands.
- Electric models such as EcoSmart ECO 11 are more affordable and easier to install but may struggle with simultaneous multi-point usage.
- Natural gas units like FOGATTI and Rheem provide higher capacity for bigger households but involve more complex installation.
- Energy efficiency varies significantly; condensing gas models tend to save more long-term but come at a higher initial price.
- Size and installation flexibility matter; compact and indoor/outdoor units offer more versatile options.
More Details on Our Top Picks
Rheem 18kW 240V Tankless Electric Water Heater, Gray
This Rheem model excels with its precise digital thermostat and self-modulating power, offering reliable temperature control and energy efficiency. Compared with larger units like the 27kW model, it’s better suited for small households or point-of-use applications where space and exact temperature matter. The copper heating elements enhance durability, but its flow rate of only 4.4 GPM limits its capacity for simultaneous multiple outlets. Installation is straightforward for experienced DIYers, yet the need for a 240V connection may pose a challenge for some. Overall, this pick is ideal for singles or couples who prioritize control and space-saving design over higher flow rates.
Pros:- Precise digital temperature control with LED display
- Self-modulating technology for energy efficiency
- Durable copper heating elements
Cons:- Flow rate of 4.4 GPM may be insufficient for larger households
- Requires 240V electrical supply, which might complicate installation
Best for: Small households or individuals needing precise temperature control in limited spaces
Not ideal for: Large families or homes with high simultaneous hot water demand, due to its limited flow rate
- Power:18kW
- Voltage:240V
- Flow Rate:up to 4.4 GPM
- Heating Elements:Copper immersion, field serviceable
- Temperature Control:Digital thermostat with LED display (+/- 1 degree)
- Connections:Bottom 3/4 inch NPT water connections
Bottom line: This model is best suited for small households requiring accurate temperature control and space efficiency.
Rheem Performance RTEX-11 11kW 240V Tankless Electric Water Heater
The Rheem RTEX-11 is tailored for small spaces, offering on-demand hot water with a compact, wall-mounted design. Unlike the larger 27kW units, it’s ideal for under-sink setups or single fixtures. Its self-modulating technology ensures energy efficiency, but its flow rate of 2.68 GPM limits its use to small demand scenarios. The digital LED makes temperature adjustments straightforward, yet it’s not suitable for whole-home use or multiple outlets simultaneously. This unit excels for individual sinks or small apartments but falls short for larger households needing higher flow rates or multiple outlets at once.
Pros:- Compact and space-saving design
- Provides continuous, on-demand hot water
- Energy-efficient with self-modulating technology
Cons:- Limited flow rate of 2.68 GPM restricts simultaneous use
- Not suitable for whole-house hot water needs
Best for: Single fixture or small apartment applications needing reliable point-of-use hot water
Not ideal for: Homes with multiple bathrooms or high demand, due to limited flow capacity
- Wattage:11 KW
- Voltage:240 V
- Flow Rate:2.68 GPM
- Efficiency:99.8%
- Maximum Pressure:150 PSI
- Connections:Side 1/2″ NPT
Bottom line: This model is ideal for small-scale, point-of-use applications with limited hot water demand.
27kW Electric Tankless Water Heater, On Demand Instant Hot Water with LED Display and Memory Function
The 27kW unit delivers up to 6.5 GPM, making it suitable for larger households or multiple simultaneous outlets. It features smart controls and a memory function for user convenience, setting it apart from simpler models like the RTEX-11. However, its high power draw requires specialized electrical setup—three 40A breakers—potentially complicating installation. Its compact size helps it fit into standard utility spaces, but the need for a dedicated electrical circuit makes it less accessible for some homeowners. Overall, this heater is a strong contender for those needing substantial hot water flow without sacrificing efficiency, yet it demands careful electrical planning.
Pros:- High flow rate of up to 6.5 GPM
- Smart controls and memory functions
- Provides continuous, on-demand hot water
Cons:- Requires complex electrical setup with three 40A breakers
- Installation may be challenging for some users
Best for: Large families or homes with high simultaneous hot water needs
Not ideal for: Small households or homes with limited electrical capacity due to high power requirements
- Power:27kW
- Voltage:240V
- Flow Rate:up to 6.5 GPM
- Efficiency:99.8%
- Dimensions:17.72 x 11.42 x 3.54 inches
- Connections:3/4 inch NPT
Bottom line: This unit is best suited for large households that need high hot water capacity and have the electrical infrastructure to support it.
FOGATTI Natural Gas Tankless Water Heater Indoor – Max 7.5 GPM, 170,000 BTU, CSA Certified, Compact On-Demand Hot Water Heater – Instagas Comfort 170S Series
The FOGATTI 170S series offers robust gas-powered performance with 170,000 BTU and a flow rate of 7.5 GPM, making it ideal for households with high hot water demand. Its CSA certification and durable copper heat exchanger ensure safe, reliable operation. Compared to electric models like the Rheem RTEX-11, this gas heater provides more capacity and is better suited for colder climates where electric units might struggle to keep up. Its compact footprint facilitates indoor installation, but careful attention to drainage and ventilation is required, especially below 5°F outdoor temperatures. This model suits busy homes needing large amounts of hot water quickly, but it’s less suitable for small spaces or low-demand settings.
Pros:- High BTU output of 170,000 BTU for powerful performance
- Flow rate of 7.5 GPM supports multiple outlets
- CSA certified for safety and reliability
Cons:- Requires proper drainage and ventilation, especially in cold environments
- Installation complexity may be higher due to gas line and venting needs
Best for: High-demand households in colder climates needing reliable, high-capacity hot water
Not ideal for: Small apartments or homes without proper ventilation or drainage options
- Flow Rate:7.5 GPM
- Heating Power:170,000 BTU
- Dimensions:25 x 16.3 x 7.3 inches
- Water Pressure Range:15-150 PSI
- Voltage:120V
- Certification:CSA
Bottom line: This gas heater is best for large, demanding households in colder areas where electric units can’t keep pace.
EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240V
The EcoSmart ECO 11 earns its spot as a top pick for small sinks, bathrooms, or low-flow applications, especially in warmer climates. Compared with larger models like the ECO 27, it offers less flow capacity—around 1.3 to 3.1 GPM—making it unsuitable for simultaneous multiple fixtures. Its self-modulating technology ensures energy is used only when needed, but this also means performance varies with inlet water temperature, potentially limiting its effectiveness in colder climates. Still, its compact size and digital control make it ideal for spaces where only modest hot water demand exists.
Pros:- Compact, space-saving design
- Highly energy-efficient with self-modulating tech
- Precise digital temperature control
Cons:- Limited flow rate restricts multiple simultaneous uses
- Requires professional electrical installation due to high amperage
- Performance depends on inlet water temperature
Best for: Homeowners needing reliable, on-demand hot water for a single sink or small bathroom in mild climates.
Not ideal for: Larger households or those with simultaneous hot water needs, since its flow rate is limited and performance may drop in colder conditions.
- Power:13 kW
- Voltage:240 V
- Amperage:54 A
- Flow Rate:1.3 to 3.1 GPM
- Temperature Range:80-140°F
- Dimensions:11.5 x 8 x 3.75 inches
Bottom line: This model works best for small, low-demand applications in moderate climates where space and efficiency matter most.
Titan Electric Tankless Water Heater
The Titan Electric Tankless is a straightforward choice for replacing traditional tank units with a compact, energy-efficient alternative. It provides instant hot water, but its limited flow rate means it’s less suitable for large households or multiple fixtures running simultaneously. Compared to the EcoSmart ECO 11, it offers similar size but may lack precise digital controls or advanced features, making it better suited for basic hot water needs without added bells and whistles. Its requirement for professional installation and modest capacity means it’s a practical but modest upgrade for small households.
Pros:- Provides instant hot water on demand
- Energy-efficient compared to traditional tanks
- Compact size saves space
Cons:- Requires professional installation
- Limited flow rate may not support multiple fixtures
- No advanced digital controls or features
Best for: Homeowners looking to switch from tank to tankless for basic hot water needs without high complexity or cost.
Not ideal for: Large families or homes with high simultaneous hot water demands, due to its limited flow capacity.
- Voltage:220 V
- Max Amps:54
- Type:Tankless
Bottom line: This heater makes sense for budget-conscious buyers replacing a tank system in small households or single-use applications.
EcoSmart ECO 27 Tankless Electric Water Heater, 27 kW
The EcoSmart ECO 27 stands out for its high power output—27 kW—and its suitability in colder climates, where incoming water temperatures can drop as low as 37°F. With a flow rate of around 3 GPM, it can support multiple fixtures, making it ideal for larger households. Compared with the ECO 11, it offers more capacity but at the cost of requiring a dedicated 240V circuit and more space. Its digital temperature control allows adjustments with 1-degree precision, but its higher electrical demand means professional installation is almost mandatory. This model strikes a balance between capacity and efficiency for colder environments.
Pros:- High power output supports multiple fixtures
- Effective in low incoming water temperatures
- Digital control offers precise temperature adjustments
Cons:- Requires a dedicated 240V circuit and professional installation
- Larger size may not fit in tight spaces
- Higher energy consumption compared to smaller units
Best for: Families in colder regions needing a reliable, higher-capacity electric heater for multiple outlets.
Not ideal for: Small households or those with limited electrical capacity, since it demands a significant power supply and space.
- Power:27 kW
- Voltage:240 V
- Flow Rate:3 GPM
- Dimensions:17 x 17 x 3.5 inches
- Climate Suitability:As low as 37°F
Bottom line: This heater suits larger households in cold climates where capacity and reliability outweigh installation complexity.
14kW Tankless Electric Water Heater, SIVUATEK 240V
The SIVUATEK 14kW heater excels in providing instant hot water for one or two points, such as a kitchen and bathroom, thanks to its 3.3 GPM flow rate and smart features. Its compact size and LED display make it a practical choice for homes with limited space, and its high efficiency supports energy savings. Compared with larger units like the ECO 27, it’s more suitable for small-scale use, but its maximum temperature of 131°F limits its application for those needing very hot water or higher temperature settings. Safety features like overheat protection add peace of mind, but it’s not designed for multiple simultaneous uses.
Pros:- Instant, endless hot water for 1-2 points
- High energy efficiency and cost savings
- Compact, space-saving installation
Cons:- Suitable for only a few fixtures simultaneously
- Requires a 60-amp circuit breaker
- Maximum temperature limited to 131°F
Best for: Small households or spaces where only one or two fixtures need hot water at a time.
Not ideal for: Large families or homes with multiple simultaneous hot water demands, due to its limited flow rate and temperature ceiling.
- Power Source:AC
- Wattage:14 KW
- Voltage:240 V
- Flow Rate:3.3 GPM
- Maximum Temperature:131°F
- Certifications:ETL
Bottom line: This heater is ideal for small homes or apartments where space and energy efficiency are priorities for limited hot water needs.
Rinnai RX199iN Condensing Smart Sense Tankless Water Heater, Indoor/Outdoor, Up to 11.1 GPM, 199,000 BTU
The Rinnai RX199iN stands out for its ability to operate seamlessly both indoors and outdoors, making it the most adaptable option in this lineup. Its high flow rate of 11.1 GPM ensures multiple fixtures can run simultaneously without pressure drops, a notable advantage over the Rheem RTG-70DVLN-3, which offers only 7.0 GPM. The unit’s impressive energy factor of 0.98 emphasizes its efficiency, translating into lower utility bills for high-demand households. However, the need for professional installation and the separate purchase of WiFi control can add complexity and cost. Compared to other models, its larger capacity and dual installation options make it ideal for larger families or those seeking flexibility, though it requires venting for outdoor use and additional components for smart control.
Pros:- Versatile indoor or outdoor installation options
- Supports multiple fixtures simultaneously with high flow rate
- Exceptional energy efficiency with UEF 0.98
- Compact size facilitates easier installation
Cons:- Professional installation recommended, adding cost
- WiFi control module sold separately, increasing expense
- Requires vent cap for outdoor use
Best for: Homes needing a high-capacity, all-weather solution supporting multiple simultaneous hot water demands.
Not ideal for: Small apartments or single-bathroom homes where capacity and flexibility are less critical.
- Model:RX199iN
- Flow Rate:Up to 11.1 GPM
- BTU:199,000
- Fuel Type:Natural Gas or Propane
- Indoor/Outdoor:Yes
- Energy Factor:UEF 0.98
Bottom line: This model is perfect for larger households or those needing a flexible, high-capacity tankless water heater with smart features.
Rheem RTG-70DVLN-3 High Efficiency Indoor Tankless Natural Gas Water Heater 7.0 GPM, 160,000 BTUs
The Rheem RTG-70DVLN-3 offers a compact and efficient solution tailored for smaller households, supporting 2-3 bathrooms with a flow rate of 7.0 GPM. Its space-saving wall-mounted design makes it easier to fit into tight indoor spaces, making it a solid alternative to the larger Rinnai RX199iN. While it doesn’t match the higher capacity of the RX199iN, it delivers reliable hot water with hot-start programming that prevents cold bursts, a feature absent in some lower-tier models. Its 160,000 BTU output balances energy use with performance but limits its suitability for larger households or rapid succession of hot water demands. Compared to the Novieex heater, which offers a lower flow rate, the Rheem is better suited for families with moderate hot water needs who value efficiency and space savings, though it requires professional installation and natural gas availability.
Pros:- Compact, space-saving wall-mounted design
- Reliable hot water with hot-start programming
- High efficiency and quick installation for indoor use
- Supports multiple fixtures adequately for moderate needs
Cons:- Limited to natural gas supply areas
- Requires professional installation, adding upfront cost
- Not suitable for large households with high simultaneous demand
Best for: Families with 2-3 bathrooms seeking a space-efficient, reliable hot water system.
Not ideal for: Large households or those with very high simultaneous hot water demands, where capacity may fall short.
- Flow Rate:7.0 GPM
- BTUs:160,000
- Fuel Type:Natural Gas
- Installation:Indoor wall-mounted
- Capacity:Suitable for 2-3 bathrooms
Bottom line: This heater is ideal for smaller, space-constrained homes with moderate hot water needs who prioritize efficiency.
Novieex Tankless Water Heater, Natural Gas, 4.3 GPM, 100,000 BTU, Indoor Wall-Mount, LED Display
The Novieex Tankless Water Heater offers a practical, budget-friendly option for smaller hot water needs, with a flow rate of 4.3 GPM and a 100,000 BTU output. Its LED touchscreen interface provides precise temperature control from 95°F to 149°F, enhancing ease of use over simpler models. This unit is best suited for single bathrooms or kitchen sink setups where space and cost are primary concerns. Compared with the Rheem model, it has a lower flow rate but includes safety features like anti-freezing and overheat protections, making it safer for indoor use. Its compact, lightweight design is easy to install but limits its capacity for larger families or simultaneous hot water use. Its dependence on natural gas and indoor-only installation restricts flexibility, but it remains a solid choice for modest demands and space efficiency.
Pros:- Space-saving wall-mounted design
- Precise digital temperature control
- Includes multiple safety protections
- Affordable and easy to operate
Cons:- Limited flow rate of 4.3 GPM
- Indoor use only, restricting placement options
- Dependent on natural gas availability
Best for: Individuals or small families needing a compact, affordable hot water solution for single fixtures.
Not ideal for: Large households or homes with multiple bathrooms, where higher flow rates and capacity are necessary.
- Flow Rate:4.3 GPM
- BTUs:100,000
- Maximum Temperature:149°F
- Heat Output:100,000 BTU
- Mount Type:Wall
- Special Features:LED Display, Safety Protections
Bottom line: This heater suits small households or single fixtures where budget and space are limited, but it may fall short for high-demand settings.
How We Picked
These products were selected based on a combination of performance metrics, user reviews, build quality, and value. Key criteria included flow rate capacity, energy efficiency, ease of installation, durability, and advanced features like smart controls. We prioritized models suitable for a range of household sizes and budgets, ensuring each option offers a clear advantage for specific needs. Rankings reflect a balance between price and features, with top picks delivering reliable hot water supply while maintaining reasonable costs and installation complexity.Factors to Consider When Choosing Best Tankless Water Heater
Choosing the right tankless water heater involves understanding several critical factors that impact performance, cost, and usability. Beyond initial price, it’s important to consider capacity, energy efficiency, and installation requirements. Making an informed decision helps avoid common pitfalls like undersizing or overpaying for features you don’t need. Let’s explore key considerations to help you select the best model for your home.Flow Rate and Household Size
Matching a heater’s flow rate to your household size is essential. Larger households with multiple bathrooms require units capable of delivering higher gallons per minute (GPM), like the Rinnai RX199iN, to avoid cold water surprises. Smaller homes or singles can opt for lower-capacity models like EcoSmart ECO 11, which are more affordable and easier to install. Choosing a unit with too low capacity results in inconsistent hot water, while oversizing increases upfront costs without added benefit.
Energy Source and Efficiency
Your energy source—electric or gas—significantly influences operating costs and installation complexity. Gas models tend to provide higher capacity and are better for larger households, but require venting and more complex hookups. Electric models are simpler, cheaper to install, and suitable for smaller homes, but often have lower flow rates. Energy efficiency ratings, especially for condensing models, can lead to long-term savings, which are worth considering if upfront costs are manageable.
Installation and Space Requirements
Installing a tankless heater involves considerations beyond size. Indoor models like Rheem RTEX-11 are compact but need proper ventilation if gas-powered. Outdoor units add convenience but may be affected by climate and exposure. Proper placement ensures access to power and water connections while avoiding space constraints. Homeowners should evaluate existing infrastructure and choose a model that fits their space and installation capability to prevent surprises and additional costs.
Cost and Long-Term Savings
While some units like the EcoSmart ECO 11 are budget-friendly upfront, investing in higher-end models like the Rinnai RX199iN can deliver better efficiency and durability. It’s important to weigh initial costs against potential savings on energy bills, especially with condensing gas units. Additional features such as smart controls or Wi-Fi connectivity may add to the price but can enhance usability and monitoring, offering value over time.
Additional Features and User Experience
Features like digital displays, self-modulating technology, and smart controls improve usability and efficiency. Units with LED displays or memory functions make operation straightforward, especially for beginners. Consider the importance of remote monitoring or app connectivity if you prefer more control over your system. These extras often come at a higher cost but can simplify maintenance and optimize performance.
Frequently Asked Questions
Can I install a tankless water heater myself?
Installing a tankless water heater is technically feasible for skilled DIYers, especially electric models, but it often involves complex electrical or plumbing work. Gas units require venting and adherence to safety standards, making professional installation advisable. Improper setup can lead to safety hazards, reduced efficiency, or voided warranties. Consulting a licensed technician ensures a safe, compliant, and optimal installation, especially for gas models.
How long does a tankless water heater last?
Most tankless water heaters are designed to last between 20 and 25 years with proper maintenance. Regular flushing to prevent mineral buildup, especially in hard water areas, significantly extends their lifespan. Investing in a high-quality unit and performing routine service can maximize durability and performance, making it a reliable long-term choice for your home.
Are electric tankless water heaters suitable for large households?
Electric tankless water heaters generally have lower flow rates compared to gas models, making them less ideal for large households with high hot water demands. They work well for small families or point-of-use applications, but for bigger homes, gas or larger capacity electric units are more appropriate. Overloading an electric heater can result in inadequate hot water and system strain.
What maintenance does a tankless water heater require?
Routine maintenance includes descaling or flushing the unit periodically, especially in areas with hard water. This process prevents mineral buildup that can impair performance and reduce lifespan. Checking the filters, inspecting venting (for gas models), and ensuring proper operation of controls are also recommended. Proper upkeep helps maintain efficiency and avoids costly repairs over time.
Is a condensing tankless water heater worth the extra cost?
Condensing models are more energy-efficient because they recover more heat from exhaust gases, reducing operating costs over time. While their initial price is higher, they often qualify for rebates or incentives, offsetting some costs. If long-term savings and environmental considerations matter, a condensing heater can be a smart investment, especially for large households or energy-conscious homeowners.
Conclusion
For most households seeking a reliable all-around option, the Rinnai RX199iN stands out as the best overall choice due to its high capacity and advanced features. Budget-conscious buyers aiming for efficiency without breaking the bank should consider the EcoSmart ECO 11. Larger families or homes with high hot water demands may find the Fogattti Natural Gas Tankless Water Heater or the Rheem Performance RTEX-11 more suitable. Beginners or those with limited space will appreciate compact models like the Novieex Indoor Gas Heater. Ultimately, selecting the right model depends on household size, energy source preference, and budget — use this guide to match your needs precisely.
