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Tankless Hot Water Heaters

10 Best Tankless Hot Water Heaters 2026 in the United States

#1

Winner

10.0 score

Rheem 18kW 240V Tankless Electric Water Heater, Gray

Rheem 18kW 240V Tankless Electric Water Heater, Gray

Rheem

10.0 score

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The Rheem 18kW 240V Tankless Electric Water Heater in Gray offers several appealing features for those in need of a compact and efficient water heating solution. The primary advantages of this model include its advanced self-modulation technology, which helps adjust power based on the hot water demand, ensuring energy efficiency and cost savings. Additionally, it boasts a flow rate of up to 4.4 GPM, which is suitable for small to medium households, providing enough hot water for multiple uses simultaneously.

Rating
10.0
Chosen by1,294
Temperature Rise
Size and Installation

Most important from
3954 reviews

Temperature Rise
You may feel the need to set the temp to 145 if converting from a water heater tank, but it's not necessary unless using multiple hot water devices simultaneously.
Size and Installation
Installed in a tiny house and works wonderfully.
#2
9.7 score

Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray

Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray

Rheem

9.7 score

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The Rheem RTEX-24 Electric Tankless Water Heater is a solid choice for those seeking an efficient and high-capacity water heating solution. One of its major strengths is its impressive flow rate of up to 5.9 gallons per minute (GPM), which is suitable for serving multiple fixtures simultaneously. Additionally, its 99.8% energy efficiency rating makes it an economical option, as it minimizes energy waste and reduces utility bills.

Rating
9.7
Flow Rate (GPM)
Energy Efficiency
Temperature Rise

Most important from
3954 reviews

Flow Rate (GPM)
Consistency is key; as long as you have power, you never run out of hot water, making it perfect for households with high hot water demands.
Energy Efficiency
We are very pleased with the product's efficiency and excellent workmanship.
Temperature Rise
Installation was straightforward, and the unit worked exactly as intended, heating very quickly.
Size and Installation
The compact size is a major plus, fitting easily into small spaces while delivering a continuous hot water supply.
#3
9.4 score

Rheem RTGH-95DVLN-3 RTGH Series 9.5 GPM 199,900 BTU 120 Volt Residential Indoor Natural Gas Tankless Water Heater Stainless Steel

Rheem RTGH-95DVLN-3 RTGH Series 9.5 GPM 199,900 BTU 120 Volt Residential Indoor Natural Gas Tankless Water Heater Stainless Steel

Rheem

9.4 score

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The Rheem RTGH-95DVLN-3 is a robust tankless water heater designed for residential indoor use with natural gas. Its standout feature is the impressive flow rate, ranging from 0.4 to 9.5 gallons per minute (GPM), making it suitable for larger households with higher hot water demands. The energy efficiency is also notable at 0.93, meaning it can help reduce energy bills compared to traditional water heaters.

Rating
9.4
Temperature Rise
Size and Installation

Most important from
57 reviews

Temperature Rise
Impressive performance with no issues post-installation; the temperature adjustment was minimal.
Size and Installation
Installation is straightforward, and the unit is not as heavy as most.

Top 10 Best Tankless Hot Water Heaters 2026 in the United States

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Slide 1

Ranein

Ranein 65,000 BTU RV Tankless Water Heater, High Altitude Available, 12V, CSA Certificated, with Thermostatic Chamber and Multi-function Controller, On Demand Instant Hot Water Heater

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#1

Winner

10.0  score
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Rheem

Rheem 18kW 240V Tankless Electric Water Heater, Gray

Flow Rate (GPM): 4.4
Energy Efficiency: self-modulation technology
Fuel Type: Electric
Size and Installation: 14.5"W x 18.25"H, 3/4 inch NPT

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Chosen by 1294 this week

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Slide 1

Ranein

Ranein 65,000 BTU RV Tankless Water Heater, High Altitude Available, 12V, CSA Certificated, with Thermostatic Chamber and Multi-function Controller, On Demand Instant Hot Water Heater

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#2
9.7  score
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Rheem

Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray

Flow Rate (GPM): 5.9
Energy Efficiency: 99.8%
Fuel Type: Electric
Size and Installation: 17.63"W x 18.25"H x 3.5"D

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#3
9.4  score
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Rheem

Rheem RTGH-95DVLN-3 RTGH Series 9.5 GPM 199,900 BTU 120 Volt Residential Indoor Natural Gas Tankless Water Heater Stainless Steel

Flow Rate (GPM): 0.4 to 9.5
Energy Efficiency: 0.93
Fuel Type: Natural Gas
Temperature Rise: 100 to 140°F
Size and Installation: 17.7"W x 23.7"H, 59.9 lbs
Warranty and Support: Heat Exchanger: 15 years

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#4
9.1  score
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Rinnai

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

Flow Rate (GPM): 11.1 gallons per minute
Energy Efficiency: UEF 0.98
Fuel Type: natural gas or propane
Temperature Rise: 140°F
Size and Installation: 19"W x 31"H, 58 lbs, wall mount

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#5
9.1  score
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Rinnai

NEW Rinnai RX130iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater, Indoor or Outdoor Water Heater, Up to 7.1 GPM, 130,000 BTU

Flow Rate (GPM): 7.1 Gallons Per Minute
Energy Efficiency: UEF rating 0.97
Fuel Type: Natural Gas or Propane
Size and Installation: 19"W x 31"H, indoor/outdoor

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#6
8.8  score
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Stiebel Eltron

Stiebel Eltron Tankless Water Heater – Tempra 36 Plus – Electric, On Demand Hot Water, Eco, White

Flow Rate (GPM): 1.5 Gallons Per Minute
Energy Efficiency: High
Fuel Type: Electric
Temperature Rise: 140 Degrees Fahrenheit
Size and Installation: 16.63"W x 14.5"H, Wall Mount

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#7
8.5  score
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Rinnai

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

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#8
8.2  score
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Rinnai

Rinnai RE199iN Non-Condensing Natural Gas Tankless Water Heater, Up to 9.8 GPM, Indoor Installation, 199,000 BTU

Flow Rate (GPM): 9.8 Gallons Per Minute
Energy Efficiency: High Efficiency
Fuel Type: Natural Gas
Temperature Rise: Max Temperature 140°F
Size and Installation: 14.05"W x 27.28"H, Wall Mount
Warranty and Support: 15yr heat exchanger, 5yr labor

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#9
7.0  score
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Rinnai

Rinnai RE199eP Non-Condensing Propane Tankless Water Heater, Up to 9.8 GPM, Outdoor Installation, 199,000 BTU

Flow Rate (GPM): 9.8 Gallons Per Minute
Energy Efficiency: Meets SCAQMD 14 ng/J or 20 ppm
Fuel Type: Liquid Propane
Temperature Rise: Up to 140 Degrees Fahrenheit
Size and Installation: 14.05"W x 27.34"H, Wall Mount
Warranty and Support: Up to 15 years heat exchanger

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#10
7.0  score
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Rinnai

Rinnai RE180iP Non-Condensing Propane Tankless Water Heater, Up to 8.5 GPM, Indoor Installation, 180,000 BTU

Flow Rate (GPM): 8.5 gallons per minute
Energy Efficiency: High efficiency
Fuel Type: Propane
Temperature Rise: 160 degrees Fahrenheit
Size and Installation: 14.05"W x 27.24"H, wall mount
Warranty and Support: 15yr heat exchanger, 5yr labor, 1yr parts

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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.

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