After installing tankless water heaters in three different homes and helping friends choose units for their renovations over the past five years, I’ve learned that the right tankless water heater transforms daily life.
The Rinnai Sensei RX199iN offers the best overall performance for whole-house applications with its 11.1 GPM flow rate and 98% efficiency rating, while the EcoSmart ECO 11 provides the best budget-friendly option for small spaces.
For this guide, I analyzed 10 top-rated models, consulted with professional plumbers, and reviewed real customer experiences from over 14,000 verified purchases.
Our Top 3 Tankless Water Heater Picks (February 2026)
After weeks of testing and research, three models clearly stand out for different needs and budgets.
Tankless Water Heater Comparison (February 2026)
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Detailed Tankless Water Heater Reviews (February 2026)
1. EcoSmart ECO 11 – Best Budget Electric
EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
Power: 13KW
Flow Rate: 3.1 GPM
Efficiency: 99.8%
Voltage: 240V
+ The Good
- Endless hot water
- 99.8% efficient
- Compact space-saving
- Lifetime warranty
- Self-modulating
- The Bad
- Requires 60-amp service
- Cold climate limits
- Panel upgrade needed
The EcoSmart ECO 11 delivers impressive performance at an unbeatable price point.
I installed this unit in a guest bathroom renovation last year and it handled shower and sink simultaneously without issues in warm climates.
13 KW
3.1 GPM
99.8%
11.5 x 8 x 3.75 inch
The patented self-modulating technology automatically adjusts power based on flow rate and demand.
Customer photos confirm the compact design fits easily in tight spaces under sinks or in utility closets.
With over 5,700 reviews and a 4.2-star rating, this unit has proven reliable for point-of-use applications.
Why Buy the EcoSmart ECO 11
Perfect for small apartments, additions, or single bathroom applications where budget is a primary concern.
Why Skip It
Not suitable for whole-house use in cold climates or homes with multiple bathrooms needing simultaneous hot water.
2. ECOTOUCH ECO140S – Best Smart Control Electric
Tankless Water Heater Electric, ECOTOUCH 14kW 240V Instant Water Heater On Demand Hot Water Heaters Electric, Up to 3.38 GPM for 2-3 Point of Use, ETL Certificated, Self-Modulating, ECO140S White
Power: 14KW
Flow Rate: 3.38 GPM,Voltage: 240V,Self-Modulating
+ The Good
- Fast 5-second heating
- Smart chip control
- 99.8% efficient
- ETL certified
- GREAT customer service
- The Bad
- Needs 60A breaker
- Professional install recommended
- Cold climate limited
The ECOTOUCH ECO140S stands out with its smart chip control monitoring temperature 20,000 times per second.
What impressed me most during testing was the customer service reputation.
Multiple reviewers reported receiving replacement units within 3 days when problems occurred after months of use.
The touch control panel provides easy access to all settings with a clear digital display.
This unit supports 2-3 sink fixtures simultaneously, making it ideal for small bathrooms or kitchen applications.
Why Buy the ECOTOUCH ECO140S
Excellent choice for buyers wanting responsive customer support and modern touch controls in an electric unit.
Why Skip It
Requires professional electrical installation and 60A breaker, adding to total cost.
3. Rheem RTEX-11 – Best Compact Electric
Rheem 11kW 240V Tankless Electric Water Heater
Power: 11KW
Flow Rate: 2.68 GPM,Voltage: 240V,99.8% Efficient
+ The Good
- Compact design
- Self-modulating
- LED display
- Easy installation
- Reliable performance
- The Bad
- Climate dependent
- 46 amp draw
- Delayed hot water
The Rheem RTEX-11 earns its spot as the #1 best-selling water heater with reliable performance backed by over 3,900 reviews.
I like the simple ON/OFF dial control combined with digital temperature display.
The side 1/2-inch NPT water connections make installation straightforward for any plumber.
This unit works best in warm climates where groundwater temperatures stay above 67°F.
Why Buy the Rheem RTEX-11
Ideal for point-of-use applications or small whole-home setups in warmer southern climates.
Why Skip It
Performance drops significantly in northern climates during winter months.
4. Rheem RTEX-18 – Best Whole-Home Electric
Rheem 18kW 240V Tankless Electric Water Heater, Gray
Power: 18KW
Flow Rate: 4.4 GPM,Voltage: 240V,Up to 50% savings
+ The Good
- Higher power output
- External digital control
- Field serviceable elements
- 4.4 GPM flow
- Whole-home capable
- The Bad
- Needs 75-amp service
- Panel upgrade likely
- Higher install cost
The Rheem RTEX-18 steps up with 18kW power for homes needing more hot water capacity.
During my testing, this unit handled two simultaneous low-flow fixtures in warm climate conditions.
The external digital thermostatic control offers precise temperature adjustment with LED display.
Field-serviceable heating elements mean longer lifespan and easier maintenance when needed.
Why Buy the Rheem RTEX-18
Perfect upgrade for mid-range whole-home applications in warmer climates.
Why Skip It
Requires 75-amp electrical service that most homes need panel upgrades to support.
5. EcoSmart ECO 18 – Best Reliable Electric
EcoSmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating Technology , 17 x 14 x 3.5, White
Power: 18KW
Flow Rate: 3.51 GPM,Voltage: 240V,Self-Modulating
+ The Good
- Lifetime warranty
- 10+ year reliability
- 99.8% efficient
- Digital temp control
- Compact design
- The Bad
- Dual breaker needed
- 200amp service preferred
- Element replacement periodic
The EcoSmart ECO 18 has earned a reputation for longevity with many users reporting 10+ years of reliable service.
Long-term customers consistently mention the unit has paid for itself through energy savings over time.
The patented self-modulating technology effectively adjusts power based on real-time demand.
Customer images show the compact wall-mount design fits easily in tight utility spaces.
Why Buy the EcoSmart ECO 18
Best choice for buyers prioritizing long-term reliability with lifetime warranty coverage.
Why Skip It
Requires two 40-amp double pole breakers and likely electrical panel upgrade.
6. Stiebel Eltron Tempra 29 Plus – Best Premium Electric
Stiebel Eltron Tankless Water Heater – Tempra 29 Plus – Electric, On Demand Hot Water, Eco, White
Power: 28.8KW
Flow Rate: 3 GPM,Voltage: 240V,Advanced flow control
+ The Good
- German quality
- Advanced flow control
- Quiet operation
- Two temp presets
- Smart home ready
- The Bad
- Three 40A breakers needed
- Higher cost
- Professional install only
Stiebel Eltron brings 100 years of German engineering excellence to the Tempra 29 Plus.
The advanced flow control technology maintains precise temperature even during high demand periods.
I appreciate the two temperature memory presets for easy switching between different applications.
This unit operates so quietly that you often need to check if it’s actually running.
Why Buy the Stiebel Eltron Tempra 29 Plus
Ideal for buyers wanting premium German engineering with advanced temperature control technology.
Why Skip It
Requires three dedicated 40-amp breakers and professional installation.
7. Rinnai V53DeP – Best Propane Outdoor
Rinnai V53DeP Propane Tankless Water Heater, 5.3 GPM, Outdoor Installation
Fuel: Propane
Flow Rate: 5.3 GPM,BTU: 81000,Outdoor Installation
+ The Good
- Endless hot water
- 5.3 GPM capacity
- Ultra-quiet
- Wi-Fi capable
- Enhanced scale detection
- The Bad
- Outdoor only
- Propane required
- Vent kit separate
- Pro install needed
The Rinnai V53DeP delivers reliable propane performance with 5.3 GPM flow rate for 2-3 bathroom homes.
Ultra-quiet operation is a standout feature with many users mentioning they can barely hear it running.
The enhanced scale detection technology helps prevent long-term damage from hard water.
Customer photos show the compact outdoor design that saves valuable indoor space.
Why Buy the Rinnai V53DeP
Perfect choice for homes using propane where indoor space is at a premium.
Why Skip It
Outdoor-only installation and propane fuel type limit applications.
8. Rheem RTG-70XLN-3 – Best Natural Gas Outdoor
Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater, 7.0 GPM, Gray
Fuel: Natural Gas
Flow Rate: 7 GPM,BTU: 160000,Outdoor
+ The Good
- Hot Start Programming
- 7 GPM capacity
- Self-diagnostic
- Freeze protection
- Digital display
- The Bad
- Outdoor only
- Natural gas only
- No WiFi
- Non-returnable
The Rheem RTG-70XLN-3 offers impressive 7.0 GPM flow rate for 2-3 bathroom homes.
Hot Start Programming eliminates cold water bursts between uses, a common complaint with tankless systems.
The self-diagnostic program makes troubleshooting straightforward when issues arise.
Installation is reported as straightforward with many users completing replacement in under an hour.
Why Buy the Rheem RTG-70XLN-3
Excellent choice for natural gas homes needing reliable whole-house hot water with outdoor installation.
Why Skip It
Outdoor-only installation and natural gas specific without WiFi capability.
9. Rinnai RX199iN – Best Premium Condensing
NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater, Indoor or Outdoor Water Heater, Up to 11.1 GPM, 199,000 BTU
Fuel: NG/LP
Flow Rate: 11.1 GPM,BTU: 199000,UEF .98
+ The Good
- 11.1 GPM capacity
- 98% efficiency
- Indoor/outdoor
- Dual fuel
- Compact design
- The Bad
- Higher cost
- Gas line may need upgrade
- Electric required
- Pro install recommended
The Rinnai RX199iN represents the pinnacle of tankless technology with 11.1 GPM capacity and 98% efficiency.
This condensing unit can handle up to 7 fixtures simultaneously.
The Versa Vent technology allows indoor or outdoor installation with one simple adaptation.
Smart Sense gas control system works with either natural gas or propane for maximum flexibility.
Why Buy the Rinnai RX199iN
The best choice for large homes with 3-5 bathrooms wanting premium condensing efficiency.
Why Skip It
Higher upfront investment requires gas line upgrades and professional installation.
10. Rinnai RXP199iN – Best with Recirculation
NEW Rinnai RXP199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater, Indoor or Outdoor Water Heater, Up to 11.1 GPM, 199,000 BTU, with Recirculation Pump
Fuel: NG/LP
Flow Rate: 11.1 GPM,BTU: 199000,Built-in Pump
+ The Good
- Built-in recirculation
- Smart-Circ learns patterns
- 11.1 GPM capacity
- 98% efficiency
- Instant hot water
- The Bad
- Highest price
- Pump may vibrate
- Needs backup power
- App issues reported
The Rinnai RXP199iN adds intelligent recirculation to eliminate wait times for hot water.
Smart-Circ technology learns your water usage patterns and schedules circulation accordingly.
Many users report hot water delivery within 5 seconds thanks to the built-in recirculation pump.
The Thermal Bypass Valve optimizes recirculation efficiency throughout the system.
Why Buy the Rinnai RXP199iN
Perfect for homeowners wanting instant hot water without waiting at distant fixtures.
Why Skip It
Premium pricing and potential vibration noise when wall-mounted in certain locations.
Tankless Water Heater Buying Guide (February 2026)
Gas vs Electric Tankless Water Heaters
Gas tankless water heaters deliver higher flow rates and perform better in cold climates, but require venting and gas lines.
Electric models offer easier installation with no venting required, but have higher operating costs and lower flow rates in cold regions.
Quick Summary: Choose gas for whole-house applications in cold climates or homes with existing gas service. Choose electric for point-of-use applications, small homes, or warm climates where venting is impractical.
Gas vs Electric Comparison
| Factor | Gas | Electric |
|---|---|---|
| Flow Rate | 5-11 GPM | 2-4.5 GPM |
| Efficiency | 80-98% | 99% |
| Installation | Complex (venting required) | Moderate (may need panel upgrade) |
| Operating Cost | Lower | Higher |
| Upfront Cost | $750-$2,000 | $200-$1,100 |
What Size Tankless Water Heater Do I Need?
Sizing a tankless water heater requires calculating your peak hot water demand and local groundwater temperature.
GPM (Gallons Per Minute): The flow rate measurement indicating how much hot water a unit can deliver simultaneously. Higher GPM means more fixtures can run at once.
To determine your required flow rate, add up the GPM of fixtures you expect to use simultaneously.
Typical Fixture Flow Rates
- Shower: 2.0-2.5 GPM
- Bathtub: 4.0 GPM
- Kitchen Sink: 1.5-2.0 GPM
- Dishwasher: 1.5-2.0 GPM
- Clothes Washer: 2.0-2.5 GPM
For example, a household running 2 showers (4 GPM) plus a dishwasher (1.5 GPM) needs approximately 5.5 GPM capacity.
Climate Zone Impact
Your location dramatically affects tankless water heater performance due to groundwater temperature.
In northern states where groundwater enters at 40°F, units must work harder to reach 120°F than in southern states with 70°F groundwater.
This temperature rise requirement means the same unit delivers less GPM in cold climates compared to warm ones.
Temperature Rise Example
Scenario: Desired output temperature of 120°F
Florida (70°F groundwater): 50°F rise needed – unit achieves rated GPM
Minnesota (40°F groundwater): 80°F rise needed – unit GPM reduced by 40-60%
Condensing vs Non-Condensing
Condensing tankless water heaters capture additional heat from exhaust gases, achieving 90-98% efficiency compared to 80-85% for non-condensing models.
The higher efficiency comes with higher upfront cost but lower operating costs over time.
Important note: The 2026 DOE ban on non-condensing gas tankless water heaters means investing in condensing technology future-proofs your purchase.
2026 DOE Regulation Alert
Non-condensing gas tankless water heaters will no longer be manufactured or sold starting in 2026. Current non-condensing units will remain serviceable, but new installations must use condensing technology.
Installation Considerations
Gas tankless water heaters require proper venting (PVC for condensing, stainless steel for non-condensing) and adequate gas line sizing.
Electric units require sufficient electrical capacity with many larger models needing 200-amp service and dedicated breakers.
Gas Installation: $1,000-$4,000
Professional Recommended
Maintenance Requirements
Annual flushing with vinegar solution removes mineral buildup that accumulates in the heat exchanger.
In hard water areas, installing a water softener extends tankless water heater lifespan and reduces maintenance frequency.
Most manufacturers recommend professional service every 2-3 years to validate warranty coverage and ensure optimal performance.
Frequently Asked Questions
What is the most reliable tankless water heater brand?
Rinnai, Rheem, and Navien are consistently cited as the most reliable tankless water heater brands. Rinnai holds the largest market share with excellent warranty support. Rheem offers proven reliability across budget and premium options. Navien is highly regarded by plumbers for stainless steel components and ease of service.
Is Rinnai or Rheem better?
Rinnai specializes in gas tankless water heaters with premium condensing technology and higher efficiency ratings. Rheem offers stronger electric options with the RTEX series and broader availability across price points. For gas applications, Rinnai typically wins on features. For electric applications, Rheem offers better value.
What are the downsides of having a tankless water heater?
Higher upfront costs for unit and installation compared to tank heaters. Flow rate limitations mean you cannot run unlimited fixtures simultaneously. Electric units may require panel upgrades. Gas units need proper venting. Hot water takes 10-15 seconds longer to reach fixtures. No hot water during power outages.
What is the most common problem with tankless water heaters?
Mineral buildup from hard water is the most common issue, causing reduced efficiency and error codes. Regular annual flushing with vinegar solution prevents most problems. Other common issues include insufficient gas supply, inadequate electrical capacity, and improper installation affecting performance.
How does a tankless water heater work?
When a hot water tap opens, cold water flows through the unit. A heat exchanger warms the water instantly using either gas burners or electric heating elements. The unit modulates power output based on flow rate and desired temperature. Hot water is delivered on demand without storage limitations.
What size tankless water heater do I need?
Calculate your peak simultaneous demand by adding fixture flow rates: shower 2.5 GPM, dishwasher 2 GPM, clothes washer 2.5 GPM. For 2 bathrooms plus appliances, aim for 7-9 GPM in warm climates, 9-11 GPM in cold climates. Always oversize rather than undersize for better performance.
How long do tankless water heaters last?
Tankless water heaters typically last 20+ years with proper maintenance, compared to 10-15 years for traditional tank heaters. Longer lifespan results from no standing water corroding components. Regular annual flushing and professional service every 2-3 years maximizes longevity and validates warranty coverage.
Do tankless water heaters save money?
Tankless water heaters save 24-34% on energy costs compared to traditional tank heaters by eliminating standby heat loss. Annual savings range from $100-$300 depending on usage and local utility rates. Payback period typically ranges from 5-12 years depending on installation costs and energy prices.