Best 40 AMP Tankless Water Heater in 2025
Updated on July 2025
#1
Recommended
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- Continuous supply of hot water on demand
- Space-saving design eliminates the need for venting; features two temperature memory presets for easy adjustments
- Requires hard-wiring to 240 or 208-volt electric service, with maximum draw of 28,800 watts at 240 volts or 21,600 watts at 208 volts
- Needs three dedicated 40 amp breakers with 8 gauge copper wiring and a minimum of 200 amp total service for installation.
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- Continuous supply of hot water on demand
- Space-saving design eliminates the need for venting; features two temperature memory presets for easy adjustments
- Requires hard-wiring to 240 or 208-volt electric service, with maximum draw of 28,800 watts at 240 volts or 21,600 watts at 208 volts
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#2
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- External thermostatic control with LED display offers +/- 1 degree accuracy
- Self-modulation technology adjusts power according to hot water demand
- Durable copper immersion heating elements with serviceable design; flow rate up to 4.4 GPM
- Bottom 3/4 inch NPT water connections facilitate straightforward installation
- Threaded design allows for easy replacement and includes digital temperature display
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- External thermostatic control with LED display offers +/- 1 degree accuracy
- Self-modulation technology adjusts power according to hot water demand
- Durable copper immersion heating elements with serviceable design; flow rate up to 4.4 GPM
- Bottom 3/4 inch NPT water connections facilitate straightforward installation
- Threaded design allows for easy replacement and includes digital temperature display
#3
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- ON/OFF dial control with a digital temperature display
- Self-modulating power control for efficiency
- 11kW model provides a flow rate of up to 2.68 GPM
- Features side 1/2" NPT water connections
- Delivers consistent and continuous hot water on demand
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- ON/OFF dial control with a digital temperature display
- Self-modulating power control for efficiency
- 11kW model provides a flow rate of up to 2.68 GPM
- Features side 1/2" NPT water connections
- Delivers consistent and continuous hot water on demand
#4
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- ON/OFF dial control with a digital temperature display
- Self-modulating power for efficient energy use
- Delivers flow rates up to 1.95 GPM at 8 kW
- 1/2" NPT water connections on the side
- Provides continuous hot water on demand
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- ON/OFF dial control with a digital temperature display
- Self-modulating power for efficient energy use
- Delivers flow rates up to 1.95 GPM at 8 kW
- 1/2" NPT water connections on the side
- Provides continuous hot water on demand
#5
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- Provides instant hot water on demand with a powerful 8kW heating system, suitable for up to 2 faucets and a flow rate of 1.56GPM at a 35°F temperature rise.
- Features a leak-proof design thanks to a cast aluminum heating chamber and a separated heating element, reducing the risk of water leaks and ensuring durability.
- Utilizes self-modulating technology to optimize energy consumption, achieving 99% heating efficiency and potentially saving up to 60% on water heating costs compared to traditional water heaters; compact design saves space by eliminating the need for a large water tank.
- ETL certified for safety with features like overheating protection and automatic shutoff when no water is detected; includes standard 1/2 NPT side water connections for easy integration.
- Requires a 40AMP double pole breaker and 8AWG wiring for straightforward installation.
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- Provides instant hot water on demand with a powerful 8kW heating system, suitable for up to 2 faucets and a flow rate of 1.56GPM at a 35°F temperature rise.
- Features a leak-proof design thanks to a cast aluminum heating chamber and a separated heating element, reducing the risk of water leaks and ensuring durability.
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#6
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- Tankless design for continuous hot water
- Operates at 220 volts for efficient performance
- Handles a maximum load of 54 amps
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- Tankless design for continuous hot water
- Operates at 220 volts for efficient performance
- Handles a maximum load of 54 amps
#7
19% Off
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- Energy-efficient electric water heater providing instant hot water without preheating.
- High-performance cast aluminum heater ensures safety by effectively separating water and electricity while resisting scale and corrosion.
- User-friendly LED display and IMD touch screen for precise temperature control.
- Features over-temperature protection and a thermostat for safe operation, ideal for families or commercial use.
- Compact wall-mount design optimizes space; installation requires specific circuit breakers and power cables, professional assistance recommended.
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- Energy-efficient electric water heater providing instant hot water without preheating.
- High-performance cast aluminum heater ensures safety by effectively separating water and electricity while resisting scale and corrosion.
- User-friendly LED display and IMD touch screen for precise temperature control.
- Features over-temperature protection and a thermostat for safe operation, ideal for families or commercial use.
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#8
31% Off
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- Provides unlimited hot water on demand; temperature is continuously monitored for consistent performance within 1 degree of the set temperature
- Compact design; 90% smaller than traditional tank heaters and can be installed on walls or at points of use
- Highly energy-efficient; operates at 99% thermal energy efficiency by heating water only when needed
- Suitable for small applications; ideal for bathrooms, sinks, or offices with a flow rate of 1.3 to 3.1 gallons per minute based on inlet water temperature
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- Provides unlimited hot water on demand; temperature is continuously monitored for consistent performance within 1 degree of the set temperature
- Compact design; 90% smaller than traditional tank heaters and can be installed on walls or at points of use
- Highly energy-efficient; operates at 99% thermal energy efficiency by heating water only when needed
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#9
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- Provides up to 4.8 GPM of hot water on demand, suitable for 2-3 simultaneous points of use.
- Features 98% energy efficiency, reducing electricity costs by up to 60%, and delivers hot water in just 3 seconds.
- Includes multiple safety features such as leakage, over-temperature, and high voltage protection; ETL certified for safety.
- Equipped with an LED display for real-time temperature updates, accurate to within 1℉, with a temperature range of 86-140℉.
- Designed for easy installation with standard connections, requires 2 x 240V/40A breakers, and has a compact size for space-saving.
- Comes with 2 years of return and exchange support and offers long-term professional technical consulting.
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- Provides up to 4.8 GPM of hot water on demand, suitable for 2-3 simultaneous points of use.
- Features 98% energy efficiency, reducing electricity costs by up to 60%, and delivers hot water in just 3 seconds.
- Includes multiple safety features such as leakage, over-temperature, and high voltage protection; ETL certified for safety.
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#10
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- Provides instant hot water in just 3 seconds, ensuring a continuous supply without wait time.
- Utilizes self-modulating technology for efficient heating, saving up to 60% on energy costs compared to traditional heaters.
- Maintains stable water temperature with auto-adjusting energy consumption based on incoming water flow and temperature.
- Features an easy installation process with overheating protection and auto shut-off for safety and maintenance.
- Compact wall-mounted design saves floor space and fits well in limited areas while supporting high power requirements.
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- Provides instant hot water in just 3 seconds, ensuring a continuous supply without wait time.
- Utilizes self-modulating technology for efficient heating, saving up to 60% on energy costs compared to traditional heaters.
- Maintains stable water temperature with auto-adjusting energy consumption based on incoming water flow and temperature.
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