Best High Capacity Tankless Water Heaters Updated May 2025
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Best High Capacity Tankless Water Heaters
2025 Buyer's GuideUpdated May 2025
Advertiser disclosure About our rankings
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Best Overall

9.8

1

9.8

Ranein Electric Tankless Water Heater, 18kW 240V on Demand Instant Endless Water Heater with LED Temperature Display for Reside...
Water temperature
Functionality
Ease of installation
Quality
Space saving
Value for money
Save 11%
Save 11%
Best Overall

9.8

1
Ranein Electric Tankless Water Heater, 18kW 240V on Demand Instant Endless Water Heater with LED Temperature Display for Reside...
Water temperature
Functionality
Ease of installation
Quality
Space saving
Value for money
Save 11%

9.7

2

9.7

Ranein 65,000 BTU RV Tankless Water Heater, High Altitude Available, 12V, CSA Certificated, with Thermostatic Chamber, External...
Ease of installation
Functionality
Water supply
Value for money
Water heater
Fit

9.7

2
Ranein 65,000 BTU RV Tankless Water Heater, High Altitude Available, 12V, CSA Certificated, with Thermostatic Chamber, External...
Ease of installation
Functionality
Water supply
Value for money
Water heater
Fit
Premium Pick

9.5

3

9.5

NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater, Indoor or Outdoor Water Heater, Up to 1...
Ease of installation
Heat capacity
Water temperature
Design
Works great
Energy efficiency
Premium Pick

9.5

3
NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater, Indoor or Outdoor Water Heater, Up to 1...
Ease of installation
Heat capacity
Water temperature
Design
Works great
Energy efficiency

9.3

4

9.3

ThermoMate 102,000 BTU 4.7 GPM Natural Gas Tankless Water Heater, High Efficiency Instant On-Demand Hot Water for Whole House U...

9.3

4
ThermoMate 102,000 BTU 4.7 GPM Natural Gas Tankless Water Heater, High Efficiency Instant On-Demand Hot Water for Whole House U...

9.2

5

9.2

Rheem RTG-84DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water Heater, 8.4 GPM
Functionality
Water heating capacity
Ease of installation
Value for money
Save 10%
Save 10%

9.2

5
Rheem RTG-84DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water Heater, 8.4 GPM
Functionality
Water heating capacity
Ease of installation
Value for money
Save 10%
Best Value

9.1

6

9.1

Tankless Water Heater Electric 3000W Instant Water Heater Under Sink 110V, Portable, On Demand Hot, Small, with Digital Display...
Heat transfer
Ease of installation
Save 11%
Save 11%
Best Value

9.1

6
Tankless Water Heater Electric 3000W Instant Water Heater Under Sink 110V, Portable, On Demand Hot, Small, with Digital Display...
Heat transfer
Ease of installation
Save 11%

8.9

7

8.9

Rheem RTG-95DVLP-3 High Efficiency Non-Condensing Indoor Tankless Liquid Propane Water Heater, 9.5 GPM
Ease of installation
Functionality
Water capacity

8.9

7
Rheem RTG-95DVLP-3 High Efficiency Non-Condensing Indoor Tankless Liquid Propane Water Heater, 9.5 GPM
Ease of installation
Functionality
Water capacity

8.8

8

8.8

Rheem 18kW 240V Tankless Electric Water Heater, Gray
Ease of installation
Value for money
Space saving
Build quality

8.8

8
Rheem 18kW 240V Tankless Electric Water Heater, Gray
Ease of installation
Value for money
Space saving
Build quality

8.7

9

8.7

Rheem 11kW 240V Tankless Electric Water Heater
Heat level
Functionality
Ease of installation
Size
Longevity
Energy efficiency
Save 9%
Save 9%

8.7

9
Rheem 11kW 240V Tankless Electric Water Heater
Heat level
Functionality
Ease of installation
Size
Longevity
Energy efficiency
Save 9%
Popular

8.6

10

8.6

Ranein 65,000 BTU RV Tankless Water Heater, High Altitude Available, 12V, CSA Certificated, with Thermostatic Chamber and Multi...
Ease of installation
Functionality
Water supply
Value for money
Water heater
Fit
Popular

8.6

10
Ranein 65,000 BTU RV Tankless Water Heater, High Altitude Available, 12V, CSA Certificated, with Thermostatic Chamber and Multi...
Ease of installation
Functionality
Water supply
Value for money
Water heater
Fit

Our Top Choice

Best Overall

9.8

1

9.8

Ranein Electric Tankless Water Heater, 18kW 240V on Demand Instant Endless Water Heater with LED Temperature Display for Reside...
Water temperature
Functionality
Ease of installation
Quality
Space saving
Value for money
Save 11%
Save 11%
Best Overall

9.8

1
Ranein Electric Tankless Water Heater, 18kW 240V on Demand Instant Endless Water Heater with LED Temperature Display for Reside...
Water temperature
Functionality
Ease of installation
Quality
Space saving
Value for money
Save 11%
Related Categories
High Efficiency Water HeaterRheem Tankless Water HeaterTankless Water Heater (All)Tankless Hot Water HeaterElectric Tankless Water HeaterRheem Water Heater
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Related Categories
High Efficiency Water HeaterRheem Tankless Water HeaterTankless Water Heater (All)Tankless Hot Water HeaterElectric Tankless Water HeaterRheem Water Heater
Related Categories
High Efficiency Water HeaterRheem Tankless Water HeaterTankless Water Heater (All)Tankless Hot Water HeaterElectric Tankless Water HeaterRheem Water Heater