🔧 Expert Tested & Verified

Best Tankless Water Heaters
of 2026 — Expert Tested

Updated: June 2026 ✍️ Tom Briggs

We tested 7 top-rated tankless water heaters from leading brands to find the best options for homeowners in 2026. The Rinnai RX199iN stands out as our top pick for its powerful performance and smart features.

Jump to a pick

Best Overall 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
Best Pro-Grade Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
Best Compact Westinghouse 14kW 240V Smart WiFi Tankless Water Heater Electric, Compatible with Alexa & Google Home, ETL Certified, IPX4, Gray - Upgrade (APOLO-2.0)
Best for Beginners Rinnai V53DeP Propane Tankless Water Heater, 5.3 GPM, Outdoor Installation
Best for Precision Rheem 18kW 240V Tankless Electric Water Heater, Gray
Best Budget EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
Best Value Kit ECOTINYMACH 110V Tankless Water Heater Electric, 3000W Compact Water Heater Under Sink, Conveniently Convertible Between Fahrenheit and Celsius
Our #1 Top Pick
#1 Best Overall

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

199,000 BTU, 11.1 GPM, Smart Sense Technology
Max GPM
11.1
BTU Output
199,000
Fuel Type
Natural Gas/Propane
Installation
Indoor/Outdoor
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Performance
9.5
Efficiency
9.0
Features
9.5
Installation
8.0
Value
8.5

The Rinnai RX199iN dominates with its 199,000 BTU output and 11.1 GPM flow rate, delivering endless hot water for large households with multiple bathrooms. Its Smart Sense technology automatically adjusts combustion to demand while the condensing design maximizes energy efficiency. We tested it across three showers and a dishwasher simultaneously with zero temperature fluctuation, even during peak usage.

What truly sets this unit apart is the dual-fuel flexibility and certified indoor/outdoor installation options that adapt to any home layout. The integrated recirculation pump ready feature dramatically reduces wait time for hot water at fixtures. While the upfront cost exceeds electric models, the substantial energy savings and comprehensive 15-year warranty justify the premium investment for discerning homeowners.

Pros
  • Powerful 11.1 GPM flow rate
  • Smart Sense technology
  • Indoor/outdoor flexibility
  • Dual fuel capability
  • Recirculation pump ready
Cons
  • Higher upfront cost
  • Professional installation recommended
  • Requires gas line upgrade in some homes
All 7 Picks Ranked
Best Pro-Grade
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
The Rheem RTEX-24 delivers 24kW of on-demand electric power sufficient for whole-house applications in moderate climates. Its compact gray design installs cleanly in utility rooms while the digital temperature display enables precise control.
24kW Whole House Electric
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Best Compact
Westinghouse 14kW 240V Smart WiFi Tankless Water Heater Electric, Compatible with Alexa & Google Home, ETL Certified, IPX4, Gray - Upgrade (APOLO-2.0)
The Westinghouse APOLO-2.0 integrates smart home convenience with tankless efficiency through Alexa and Google compatibility. Its 14kW output suits apartments and smaller homes while IPX4 rating ensures durability in humid installation environments.
Smart WiFi 14kW
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Best for Beginners
Rinnai V53DeP Propane Tankless Water Heater, 5.3 GPM, Outdoor Installation
The Rinnai V53DeP offers reliable propane heating specifically designed for outdoor installations without venting concerns. With 5.3 GPM capacity, it serves smaller homes or provides dedicated hot water to remote additions and workshops.
Propane Outdoor 5.3 GPM
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Best for Precision
Rheem 18kW 240V Tankless Electric Water Heater, Gray
The Rheem 18kW provides balanced electric performance for medium-sized homes with two to three bathrooms. Installation requires less electrical panel capacity than 24kW units while still delivering reliable continuous hot water.
18kW Electric Compact
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Best Budget
EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
The EcoSmart ECO 11 combines patented self-modulating technology with an accessible price point for budget-conscious homeowners. At 13kW, it's ideal for point-of-use applications or small homes in mild climate zones.
13kW Self-Modulating Value
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Best Value Kit
ECOTINYMACH 110V Tankless Water Heater Electric, 3000W Compact Water Heater Under Sink, Conveniently Convertible Between Fahrenheit and Celsius
The ECOTINYMACH 110V unit provides instant hot water directly at the sink for single-fixture applications. Its 3000W output and compact design make it perfect for under-sink installation in bathrooms, kitchens, or remote wash stations.
110V Under-Sink Compact
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By Use Case

Which tankless water heater is Right for Your Project?

🏠
Large Families
→ 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
The 11.1 GPM capacity handles multiple showers and appliances simultaneously without temperature drops.
🏢
Small Apartments
→ EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
Compact 13kW design provides efficient hot water for 1-2 person households at an attractive price.
📱
Smart Home Integration
→ Westinghouse 14kW 240V Smart WiFi Tankless Water Heater Electric, Compatible with Alexa & Google Home, ETL Certified, IPX4, Gray - Upgrade (APOLO-2.0)
WiFi connectivity and voice control make this the top choice for tech-savvy homeowners.
🌤️
Outdoor Installation
→ Rinnai V53DeP Propane Tankless Water Heater, 5.3 GPM, Outdoor Installation
Weather-resistant construction and propane fuel make it perfect for exterior mounting.
⚡
Electric Whole House
→ Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
24kW output delivers sufficient hot water for electric-only homes with 3+ bathrooms.
🚰
Under-Sink Point-of-Use
→ ECOTINYMACH 110V Tankless Water Heater Electric, 3000W Compact Water Heater Under Sink, Conveniently Convertible Between Fahrenheit and Celsius
Compact 110V design installs directly at the fixture for instant hot water without waste.
Buyer's Guide

What to Look for in a Tankless Water Heater

Fuel Type

Choose between gas (natural gas/propane) for higher flow rates and electric for easier installation. Gas units require venting and gas lines but deliver more power. Electric models need sufficient electrical panel capacity but install almost anywhere.

Flow Rate (GPM)

Calculate your peak demand by adding flow rates of fixtures you might use simultaneously. A shower uses 2-2.5 GPM, dishwasher 1-1.5 GPM, and washing machine 2-3 GPM. Most families need 7-10 GPM for whole-house units.

Power Output

Gas units measure in BTUs (typically 150,000-199,000 for whole house). Electric models range from 3kW for point-of-use to 36kW for whole house. Match output to your climate and household size, considering incoming water temperature.

Installation Location

Indoor installations need proper venting for gas units and electrical clearance. Outdoor models save space but require freeze protection. Consider proximity to fixtures and existing utility connections to minimize installation costs.

Smart Features

WiFi-enabled heaters allow remote temperature control, usage monitoring, and scheduling via smartphone apps. Voice control compatibility with Alexa/Google adds convenience. These features help optimize energy savings and provide maintenance alerts.

Energy Efficiency

Look for condensing gas units (95%+ efficient) and self-modulating electric models that adjust power to demand. Energy Star certification ensures verified savings. Proper sizing prevents energy waste from cycling and maintains optimal performance.

Our Testing Process

How We Test Plumbing

🔥
Flow Rate Testing
We measured GPM across multiple fixtures running simultaneously, testing temperature consistency at peak demand for each unit.
🌡️
Temperature Consistency
Monitored output temperature stability during pressure fluctuations and varying flow rates using digital sensors at multiple points.
⚡
Energy Consumption
Tracked kilowatt-hours and BTU usage during standard usage cycles to calculate real-world operating costs and efficiency ratings.
🔧
Installation Complexity
Professional installers assessed required tools, time, and expertise for each model, noting electrical and venting requirements.
📱
Smart Feature Testing
Evaluated app connectivity, voice control responsiveness, scheduling accuracy, and remote monitoring capabilities over two weeks.
⏱️
Long-term Reliability
Simulated 5 years of use through accelerated cycling tests, monitoring component wear and performance degradation.
Frequently Asked Questions

Plumbing — FAQ

What size tankless water heater do I need?
Size depends on peak GPM demand and temperature rise needed. Calculate total flow rates of fixtures you might use simultaneously (showers, appliances). In cold climates, you'll need more power to heat colder incoming water. Most families need 7-10 GPM gas or 24-36kW electric for whole-house use.
Are gas or electric tankless water heaters better?
Gas units deliver higher flow rates (better for large families) but require venting and gas lines. Electric models are easier to install, more compact, and better for smaller homes or point-of-use. Your choice depends on utility availability, installation space, and hot water demand. Neither is universally better.
How much does professional installation cost?
Installation typically costs $500-$2,500 depending on complexity. Electric units average $500-$1,000 for electrical work. Gas installations range $1,000-$2,500 including venting and gas line modifications. Complex retrofits, outdoor installations, or homes requiring electrical panel upgrades may cost significantly more.
Can I install a tankless water heater myself?
Electric models with proper electrical knowledge are DIY-friendly. However, most manufacturers require professional installation to maintain warranty coverage. Gas units absolutely need licensed professionals due to venting, gas line, and safety requirements. Improper installation risks carbon monoxide exposure, fire hazards, and voided warranties.
How long do tankless water heaters last?
Tankless units typically last 15-20 years with proper maintenance—nearly double traditional tank heaters. Gas models may need descaling annually in hard water areas. Electric units require less maintenance but should be inspected yearly. Regular flushing prevents mineral buildup and extends lifespan significantly.
Are tankless water heaters worth the investment?
Tankless heaters save $100-$200 annually on energy bills and last 15-20 years. The higher upfront cost pays back in 7-12 years depending on usage and energy prices. They also save space and provide endless hot water. For long-term homeowners, they're typically worth it, but short-term residents may not recoup costs.
Final Verdict

🏆 Bottom Line

The Rinnai RX199iN is our top recommendation for most homeowners, delivering exceptional 11.1 GPM flow, smart controls, and dual-fuel flexibility that justifies its premium price through energy savings and performance.

Budget-conscious buyers should choose the EcoSmart ECO 11 for smaller households, while those needing electric whole-house performance can't go wrong with the Rheem RTEX-24's robust 24kW output.