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10 Best Tankless Hot Water Heaters 2025 in the United States
#1
Winner
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 Rinnai RX199iN is a powerful tankless water heater that stands out for its impressive flow rate of up to 11.1 gallons per minute, making it suitable for homes with multiple fixtures needing hot water simultaneously. It's designed to operate on either natural gas or propane, giving you flexibility depending on your fuel source. The energy efficiency is top-notch, boasting a UEF rating of .98, which means it uses energy very effectively, potentially saving you on utility bills.
Rating
9.7
Chosen by1,407
Flow Rate (GPM)
Fuel Type
Size and Installation
Most important from
223 reviews
#2
Ranein Natural Gas Tankless Water Heater, Indoor Max 3.6 GPM, 80,000 BTU Instant Hot Water Heater
The Ranein Natural Gas Tankless Water Heater delivers a flow rate of 3.6 gallons per minute, sufficient to supply hot water simultaneously to about two or three spots like a bathroom and kitchen. Thanks to its 80,000 BTU heating power, it provides instant hot water without the long wait common with traditional tanks. It’s designed for indoor use and includes useful safety features such as dry combustion and flame failure protection.
Rating
9.4
Flow Rate (GPM)
Energy Efficiency
Fuel Type
Most important from
329 reviews
#3
Rinnai V75IN Tankless Hot Water Heater, 7.5 GPM, Natural Gas, Indoor Installation
The Rinnai V75IN is a natural gas tankless water heater designed for indoor use, delivering a flow rate of up to 7.5 gallons per minute (GPM). This means it can efficiently provide hot water to around five appliances at the same time, making it suitable for medium-sized homes or households with moderate hot water demand. Its compact size (30" wide by 13" high) helps save space compared to traditional tank heaters.
Rating
9.2
Flow Rate (GPM)
Energy Efficiency
Fuel Type
Most important from
2754 reviews
Top 10 Best Tankless Hot Water Heaters 2025 in the United States
#1
Winner
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
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
Flow Rate (GPM): 11.1
Energy Efficiency: UEF .98
Fuel Type: Natural gas or propane
Size and Installation: 18.5"W x 30.11"H, Wall mount
Chosen by 1407 this week
Ranein Natural Gas Tankless Water Heater, Indoor Max 3.6 GPM, 80,000 BTU Instant Hot Water Heater
Ranein Natural Gas Tankless Water Heater, Indoor Max 3.6 GPM, 80,000 BTU Instant Hot Water Heater
Flow Rate (GPM): 3.6 Gallons Per Minute
Fuel Type: Natural Gas
Size and Installation: 19.09"W x 7.67"H, Wall mount
Rinnai V75IN Tankless Hot Water Heater, 7.5 GPM, Natural Gas, Indoor Installation
Rinnai V75IN Tankless Hot Water Heater, 7.5 GPM, Natural Gas, Indoor Installation
Flow Rate (GPM): 7.5 Gallons Per Minute
Energy Efficiency: Energy Factor 0.82
Fuel Type: Natural Gas
Temperature Rise: 98ºF to 140ºF
Size and Installation: 30"W x 13"H, Indoor, Pro install
Warranty and Support: 10yr heat exchanger, 5yr labor, 1yr parts
EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
Flow Rate (GPM): 3.1 Gallons Per Minute
Energy Efficiency: 99.8%
Fuel Type: Electric
Temperature Rise: Maintains water temperature within 1 degree
Size and Installation: 8"W x 11.5"H, Wall-mounted
Warranty and Support: Lifetime warranty on electronics and parts
Rinnai RE140iN Non-Condensing Natural Gas Tankless Water Heater, Up to 5.3 GPM, Indoor Installation, 140,000 BTU
Rinnai RE140iN Non-Condensing Natural Gas Tankless Water Heater, Up to 5.3 GPM, Indoor Installation, 140,000 BTU
Flow Rate (GPM): 5.3
Energy Efficiency: High
Fuel Type: Natural Gas
Size and Installation: 14.05"W x 27.28"H, Wall-mount
Warranty and Support: Up to 15 years
Related Products
Rinnai RL75IN Tankless Hot Water Heater, 7.5 GPM, Natural Gas, Indoor Installation
Rinnai RL75IN Tankless Hot Water Heater, 7.5 GPM, Natural Gas, Indoor Installation
Flow Rate (GPM): 7.5
Fuel Type: Natural Gas
Size and Installation: 17.5"W x 31"H, Indoor
Warranty and Support: Up to 12 years heat exchanger
Rinnai RE140eP Non-Condensing Propane Tankless Water Heater, Up to 5.3 GPM, Outdoor Installation, 140,000 BTU
Rinnai RE140eP Non-Condensing Propane Tankless Water Heater, Up to 5.3 GPM, Outdoor Installation, 140,000 BTU
Flow Rate (GPM): 5.3 Gallons Per Minute
Energy Efficiency: High Efficiency
Fuel Type: Propane
Size and Installation: 14.05"W x 24.64"H, Outdoor
Warranty and Support: 15yr heat exchanger, 5yr labor, 1yr parts
Rinnai RUCS75iN Tankless Hot Water Heater, 7.5 GPM, Natural Gas, Indoor Installation
Rinnai RUCS75iN Tankless Hot Water Heater, 7.5 GPM, Natural Gas, Indoor Installation
Flow Rate (GPM): 7.5 Gallons Per Minute
Energy Efficiency: High
Fuel Type: Natural Gas
Size and Installation: 34"W x 14.5"H, Wall Mount
Warranty and Support: 12yr heat exchanger, 5yr parts
#10
Rinnai REP160eN Smart-Circ Non-Condensing Natural Gas Tankless Water Heater with Built-In Recirculation Pump, Up to 6.6 GPM, Outdoor Installation, 160,000 BTU
Rinnai REP160eN Smart-Circ Non-Condensing Natural Gas Tankless Water Heater with Built-In Recirculation Pump, Up to 6.6 GPM, Outdoor Installation, 160,000 BTU
Flow Rate (GPM): 6.6 gallons per minute
Energy Efficiency: Non-condensing model
Fuel Type: Natural gas
Size and Installation: 14.05"W x 27.24"H, outdoor install
Warranty and Support: 15 years heat exchanger warranty
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Buying Guide for the Best Tankless Hot Water Heaters
Choosing the right tankless hot water heater can significantly improve your home's energy efficiency and ensure you have a reliable supply of hot water. Unlike traditional water heaters that store hot water in a tank, tankless models heat water on demand, which can save space and reduce energy costs. To find the best fit for your needs, it's important to understand the key specifications and how they relate to your household's requirements.Flow Rate (GPM)Flow rate, measured in gallons per minute (GPM), indicates how much hot water the unit can produce at a given time. This is crucial because it determines whether the heater can meet your household's hot water demands. For example, a flow rate of 3-4 GPM is suitable for small households with one or two fixtures running simultaneously, while larger households with multiple fixtures may require a flow rate of 7-10 GPM. To choose the right flow rate, consider the number of people in your home and the number of hot water fixtures you expect to use at the same time.
Energy EfficiencyEnergy efficiency is measured by the unit's Energy Factor (EF) or Uniform Energy Factor (UEF). This spec indicates how efficiently the heater converts energy into hot water. Higher EF or UEF values mean better efficiency and lower energy costs. For example, a unit with an EF of 0.8 is less efficient than one with an EF of 0.95. To pick the right one, look for models with higher efficiency ratings, especially if you are concerned about reducing your energy bills and environmental impact.
Fuel TypeTankless water heaters can be powered by electricity, natural gas, or propane. The fuel type affects installation costs, operating costs, and performance. Electric models are typically easier to install and maintain but may have higher operating costs. Gas models, on the other hand, often provide higher flow rates and are more cost-effective in the long run but require proper ventilation and may have higher upfront installation costs. Choose the fuel type based on your existing infrastructure, availability of fuel sources, and long-term cost considerations.
Temperature RiseTemperature rise refers to the difference between the incoming water temperature and the desired output temperature. This spec is important because it affects the heater's ability to provide hot water in colder climates. For instance, if the incoming water temperature is 50°F and you want it heated to 120°F, the unit needs to handle a 70°F temperature rise. To choose the right model, consider the average temperature of your incoming water and ensure the heater can achieve the desired output temperature, especially during colder months.
Size and InstallationThe physical size of the tankless water heater and its installation requirements are important factors to consider. Tankless units are generally more compact than traditional tanks, but you still need to ensure you have enough space for installation. Additionally, some models may require specific venting or electrical upgrades. To pick the right size, measure the available space and check the installation requirements of the unit. If you have limited space or specific installation constraints, look for models designed for easy installation in tight spaces.
Warranty and SupportThe warranty and support offered by the manufacturer can provide peace of mind and protect your investment. Warranties typically cover parts and labor for a certain period, and longer warranties often indicate higher quality and reliability. To choose the right model, compare the warranty terms and consider the availability of customer support and service centers. Opt for a unit with a comprehensive warranty and good customer support to ensure you can get help if any issues arise.