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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.
Customer Highlights
A summary of real customer reviews to highlight what shoppers are saying!Customer Highlights
A summary of real customer reviews to highlight what shoppers are saying!#2
Stiebel Eltron Tankless Water Heater - Tempra 29 Trend – Electric, On Demand Hot Water, Eco, White
The Stiebel Eltron Tempra 29 Trend is a strong contender in the tankless hot water heater market, particularly suitable for those seeking an efficient and space-saving solution for whole-home hot water needs. Its continuous flow feature ensures that you won’t run out of hot water during showers or while using multiple taps, which is a significant advantage for larger households. The energy efficiency of this model is commendable, with auto-modulation that helps save power when hot water is not in demand, making it an eco-friendly option.
Customer Highlights
A summary of real customer reviews to highlight what shoppers are saying!Customer Highlights
A summary of real customer reviews to highlight what shoppers are saying!#3
Rheem RTGH-95DVELN-3 Super High Efficiency Condensing Indoor Tankless Natural Gas Water Heater, 9.5 GPM with WiFi
The Rheem RTGH-95DVELN-3 Super High Efficiency Condensing Indoor Tankless Natural Gas Water Heater is designed for those who need a reliable and efficient hot water solution for their entire home. With a flow rate of 9.5 gallons per minute, it can handle multiple applications simultaneously, making it ideal for larger households or busy families. Its energy efficiency is impressive, as it only operates when hot water is needed, leading to potential savings on energy bills.
Customer Highlights
A summary of real customer reviews to highlight what shoppers are saying!Customer Highlights
A summary of real customer reviews to highlight what shoppers are saying!Top 10 Best Tankless Hot Water Heaters 2025 in the United States
#1
Winner
9.9 score
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 1399 this week
Stiebel Eltron Tankless Water Heater - Tempra 29 Trend – Electric, On Demand Hot Water, Eco, White
Stiebel Eltron Tankless Water Heater - Tempra 29 Trend – Electric, On Demand Hot Water, Eco, White
Energy Efficiency: auto-modulation
Size and Installation: 16.63"W x 14.5"H, compact, easy installation
Warranty and Support: 7-year leakage, 3-year parts
Rheem RTGH-95DVELN-3 Super High Efficiency Condensing Indoor Tankless Natural Gas Water Heater, 9.5 GPM with WiFi
Rheem RTGH-95DVELN-3 Super High Efficiency Condensing Indoor Tankless Natural Gas Water Heater, 9.5 GPM with WiFi
Flow Rate (GPM): 9.5
Energy Efficiency: Super High Efficiency
Fuel Type: Natural Gas
Temperature Rise: 140°F
Size and Installation: 17.7"W x 23.7"H, Indoor
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
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
Related Products
Rheem 18kW 240V Tankless Electric Water Heater, Gray
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
Ranein Propane Gas Tankless Water Heater, Indoor Max 3.6 GPM, 80,000 BTU Instant Hot Water Heater
Ranein Propane Gas Tankless Water Heater, Indoor Max 3.6 GPM, 80,000 BTU Instant Hot Water Heater
Flow Rate (GPM): 3.6
Energy Efficiency: Improved energy efficiency, reduced heat loss
Fuel Type: Propane
Size and Installation: 19.09"W x 7.67"H, Wall-mount
Rheem RRTGH84DVLN3701171 Rheem RTGH Series 8.4 GPM 157,000 BTU 120 Volt Residential Indoor Natural Gas Tankless Water Heater Stainless Steel
Rheem RRTGH84DVLN3701171 Rheem RTGH Series 8.4 GPM 157,000 BTU 120 Volt Residential Indoor Natural Gas Tankless Water Heater Stainless Steel
Flow Rate (GPM): 8.4
Energy Efficiency: 0.93
Fuel Type: Natural Gas
Temperature Rise: 100 to 140°F
Size and Installation: 17.7"W x 23.7"H, Wall Mount
Warranty and Support: 1 year labor, 15 years heat exchanger
Rinnai REP199iN Smart-Circ Non-Condensing Natural Gas Tankless Water Heater with Built-In Recirculation Pump, Up to 7.9 GPM, Indoor Installation, 199,000 BTU
Rinnai REP199iN Smart-Circ Non-Condensing Natural Gas Tankless Water Heater with Built-In Recirculation Pump, Up to 7.9 GPM, Indoor Installation, 199,000 BTU
Flow Rate (GPM): 7.9
Energy Efficiency: High Efficiency
Fuel Type: Natural Gas
Size and Installation: 14.05"W x 27.24"H, Wall, Indoor
Warranty and Support: 15 years heat exchanger, 5 years labor
#10
8.3 score
Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater, 8.4 GPM
Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater, 8.4 GPM
Flow Rate (GPM): 8.4
Energy Efficiency: GAMA certified
Fuel Type: Natural Gas
Size and Installation: 13.5"W x 20.75"H, 39.2 lbs, Wall, Outdoor
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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.