Tankless water heaters save space, cut energy bills, and keep hot water flowing on demand. Compact electric units like Rheem’s 18kW or the EcoSmart ECO 11 mount neatly on a wall and deliver precise temperature control.
Powerful gas models such as the Rinnai RX199iN handle multiple showers and appliances without a bulky tank. With smart safety features and the right mix of power and flow, your home stays cozy even through winter.
| Rheem 18kW 240V Tankless Electric Water Heater Gray |
| Best Whole-Home Electric | Power (Wattage or BTU): 18,000 watts (18 kW) | Voltage: 240 Volts | Flow Rate (Gallons Per Minute, GPM): Up to 4.4 GPM | VIEW LATEST PRICE | Read Our Analysis |
| EcoSmart ECO 11 Electric Tankless Water Heater |
| Best Point-of-Use Efficiency | Power (Wattage or BTU): 13,000 watts (13 kW) | Voltage: 220-240 Volts | Flow Rate (Gallons Per Minute, GPM): Up to 3.1 GPM | VIEW LATEST PRICE | Read Our Analysis |
| Rinnai RX199iN Tankless Natural Gas Water Heater |
| Top Gas-Powered Option | Power (Wattage or BTU): 199,000 BTU (natural gas) | Voltage: 120 Volts (electrical power consumption for controls) | Flow Rate (Gallons Per Minute, GPM): Up to 11.1 GPM | VIEW LATEST PRICE | Read Our Analysis |
| Rheem RTEX-24 24kW 240V Electric Tankless Water Heater Gray |
| High Capacity Electric | Power (Wattage or BTU): 24,000 watts (24 kW) | Voltage: 240 Volts | Flow Rate (Gallons Per Minute, GPM): Not explicitly specified (whole home use, varies) | VIEW LATEST PRICE | Read Our Analysis |
| Tankless Electric Water Heater 110V 3000W Digital |
| Compact Under-Sink Heater | Power (Wattage or BTU): 3,000 watts | Voltage: 110 Volts | Flow Rate (Gallons Per Minute, GPM): 0.3 to 0.5 GPM (not suitable for showers) | VIEW LATEST PRICE | Read Our Analysis |
| ORBEK 14kW Electric Tankless Water Heater |
| Energy-Saving Mid-Range | Power (Wattage or BTU): 14,000 watts (14 kW) | Voltage: 240 Volts | Flow Rate (Gallons Per Minute, GPM): Up to 3.38 GPM | VIEW LATEST PRICE | Read Our Analysis |
| Rinnai RXP199iN Tankless Water Heater with Pump |
| Smart Gas Recirculation | Power (Wattage or BTU): 199,000 BTU (natural gas) | Voltage: 120 Volts (electrical power consumption for controls) | Flow Rate (Gallons Per Minute, GPM): Up to 11.1 GPM | VIEW LATEST PRICE | Read Our Analysis |
| Rheem 11kW 240V Tankless Electric Water Heater |
| Budget Electric Pick | Power (Wattage or BTU): 11,000 watts (11 kW) | Voltage: 240 Volts | Flow Rate (Gallons Per Minute, GPM): Up to 2.68 GPM | VIEW LATEST PRICE | Read Our Analysis |
| 110V Tankless Electric Water Heater 3000W Compact |
| Compact & Convertible | Power (Wattage or BTU): 3,000 watts | Voltage: 110 Volts | Flow Rate (Gallons Per Minute, GPM): Not explicitly specified, but compact under sink | VIEW LATEST PRICE | Read Our Analysis |
| 18kW Tankless Electric Water Heater WiFi Control |
| WiFi-Enabled Control | Power (Wattage or BTU): 18,000 watts (18 kW) | Voltage: 240 Volts | Flow Rate (Gallons Per Minute, GPM): Up to 4.3 GPM | VIEW LATEST PRICE | Read Our Analysis |
More Details on Our Top Picks
Rheem 18kW 240V Tankless Electric Water Heater Gray
For anyone residing in the Midwest who needs a reliable source of hot water for either a single shower or an entire home, the Rheem 18kW 240V Tankless Electric Water Heater stands out as a smart choice. This gray, wall-mounted unit offers a continuous supply of hot water without the bulk of traditional tanks. It efficiently delivers up to 4.4 gallons per minute and adjusts power use to match demand, helping save on energy bills. With a compact design and precise digital controls, it fits neatly in smaller spaces while maintaining steady, comfortable water temperatures throughout the house.
- Power (Wattage or BTU):18,000 watts (18 kW)
- Voltage:240 Volts
- Flow Rate (Gallons Per Minute, GPM):Up to 4.4 GPM
- Temperature Range / Max Temperature:Maximum 140°F
- Installation Type:Wall-mounted
- Energy Efficiency / Technology:99.8% efficient; self-modulating power adjustment
- Additional Feature:External digital thermostatic control
- Additional Feature:Copper immersion heating elements
- Additional Feature:Threaded 3/4″ NPT connections
EcoSmart ECO 11 Electric Tankless Water Heater
The EcoSmart ECO 11 Electric Tankless Water Heater stands out as an excellent choice for those who need reliable hot water in smaller spaces or colder climates. This compact unit fits easily on a wall and heats water on demand, keeping it steady within one degree of your chosen temperature. Ideal for a single shower or sink, it adjusts flow and power to save energy without wasting heat. Its digital control and self-modulating technology make it simple to use, while the 99% thermal efficiency means lower energy bills. Plus, the lifetime warranty offers peace of mind for long-term use.
- Power (Wattage or BTU):13,000 watts (13 kW)
- Voltage:220-240 Volts
- Flow Rate (Gallons Per Minute, GPM):Up to 3.1 GPM
- Temperature Range / Max Temperature:80°F to 140°F
- Installation Type:Wall-mounted or point-of-use
- Energy Efficiency / Technology:99% thermal efficiency; patented self-modulating technology
- Additional Feature:Patented self-modulating technology
- Additional Feature:Certified WaterSense labeled
- Additional Feature:Lifetime warranty on electronics
Rinnai RX199iN Tankless Natural Gas Water Heater
Who needs a powerful water heater that can handle multiple demands without taking up much space? The Rinnai RX199iN Tankless Natural Gas Water Heater fits perfectly. It delivers up to 11.1 gallons per minute, enough to support seven fixtures at once, making busy households a breeze. Its compact size, about the size of a small suitcase, saves precious space in your home. Designed for indoor or outdoor installation, it uses the Versa Vent system, with an outdoor vent cap required. The Smart Sense gas control guarantees efficient fuel use, while the user-friendly interface and Quick Flush feature simplify maintenance.
- Power (Wattage or BTU):199,000 BTU (natural gas)
- Voltage:120 Volts (electrical power consumption for controls)
- Flow Rate (Gallons Per Minute, GPM):Up to 11.1 GPM
- Temperature Range / Max Temperature:Maximum 140°F
- Installation Type:Wall-mounted (indoor or outdoor with venting)
- Energy Efficiency / Technology:UEF 0.98; Smart Sense gas control
- Additional Feature:Smart Sense gas control
- Additional Feature:Versa Vent system compatibility
- Additional Feature:Optional Control-R WiFi module
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater Gray
Ideal for homeowners who need a reliable supply of continuous hot water, the Rheem RTEX-24 24kW 240V Electric Tankless Water Heater stands out with its powerful 24kW heating element and precise temperature control. This model offers adjustable digital temperature settings from 80°F to 140°F, allowing users to fine-tune water heat in one-degree increments. It delivers whole-home hot water efficiently without the need for venting, saving space and energy. However, it requires a sturdy electrical setup, including 3 x 40 AMP double pole breakers and preferably a 200 AMP household service, to perform at its best. Water temperature and flow depend on local groundwater conditions, so users should consider their area’s climate to guarantee consistent performance.
- Power (Wattage or BTU):24,000 watts (24 kW)
- Voltage:240 Volts
- Flow Rate (Gallons Per Minute, GPM):Not explicitly specified (whole home use, varies)
- Temperature Range / Max Temperature:80°F to 140°F
- Installation Type:Wall-mounted
- Energy Efficiency / Technology:Energy-saving tankless design; no venting required
- Additional Feature:Requires 3 x 40 AMP breakers
- Additional Feature:ON/OFF dial control
- Additional Feature:Adjustable digital temperature display
Tankless Electric Water Heater 110V 3000W Digital
Anyone searching for a compact and efficient method to enjoy instant hot water will find the Tankless Electric Water Heater 110V 3000W Digital a smart choice. Its sleek, ultra-thin design fits easily underneath sinks in small spaces like kitchens, apartments, and RVs. The unit heats water quickly, raising temperature at up to 131°F at 0.5 gallons per minute without delays. Users can switch temperature units using a simple button press, adding convenience. Safety features include waterproofing, leakage protection, and automatic shutoff to prevent overheating. Installation is straightforward, requiring vertical mounting and standard plumbing connections, making it a reliable, energy-saving option.
- Power (Wattage or BTU):3,000 watts
- Voltage:110 Volts
- Flow Rate (Gallons Per Minute, GPM):0.3 to 0.5 GPM (not suitable for showers)
- Temperature Range / Max Temperature:Up to 131°F
- Installation Type:Under sink, vertical installation only
- Energy Efficiency / Technology:Thermal efficiency up to 98%; energy-saving
- Additional Feature:ABS material construction
- Additional Feature:Multiple safety protections
- Additional Feature:Vertical installation only
ORBEK 14kW Electric Tankless Water Heater
For households seeking a compact yet powerful water heating solution, the ORBEK 14kW Electric Tankless Water Heater offers an impressive balance of efficiency and convenience. It heats water in just three seconds, providing a steady flow rate of up to 3.38 gallons per minute, perfect for serving two to three faucets simultaneously. The heater’s digital display makes adjusting temperatures simple and precise, maintaining a stable warmth within one degree Fahrenheit. Its small size saves over half the space traditional tanks occupy, while safety features and ETL certification provide peace of mind. Installation is straightforward, supported through strong customer service and warranty coverage.
- Power (Wattage or BTU):14,000 watts (14 kW)
- Voltage:240 Volts
- Flow Rate (Gallons Per Minute, GPM):Up to 3.38 GPM
- Temperature Range / Max Temperature:Up to 140°F
- Installation Type:Floor mounting type
- Energy Efficiency / Technology:High efficiency with water-electricity separation; reduces scale and corrosion
- Additional Feature:Water-electricity separation design
- Additional Feature:ETL certified safety
- Additional Feature:Built-in chip temperature control
Rinnai RXP199iN Tankless Water Heater with Pump
At a time a household demands a powerful water heater that can handle multiple fixtures at once without sacrificing energy efficiency, the Rinnai RXP199iN Tankless Water Heater with Pump stands out as a top contender. Compact like a small suitcase, it fits indoors or outdoors with versatile venting options. It delivers up to 11.1 gallons per minute, supporting seven fixtures simultaneously, while maintaining a high energy factor of 0.98. The Smart-Circ pump learns your water use, cutting wait times and saving energy. Add Wi-Fi control for remote monitoring, and you have a modern, space-saving solution that truly understands your home’s needs.
- Power (Wattage or BTU):199,000 BTU (natural gas)
- Voltage:120 Volts (electrical power consumption for controls)
- Flow Rate (Gallons Per Minute, GPM):Up to 11.1 GPM
- Temperature Range / Max Temperature:Maximum 140°F
- Installation Type:Wall-mounted (indoor or outdoor with venting)
- Energy Efficiency / Technology:UEF 0.98; Smart-Circ Intelligent Recirculation pump; Energy Star qualified
- Additional Feature:Smart-Circ Intelligent Recirculation pump
- Additional Feature:Quick Flush maintenance feature
- Additional Feature:Energy Star qualified
Rheem 11kW 240V Tankless Electric Water Heater
The Rheem 11kW 240V Tankless Electric Water Heater stands out as a smart choice for those seeking reliable hot water without the bulk of traditional tanks. It offers an 11kW self-modulating power control that adjusts to your needs, helping save energy while providing a steady flow rate of up to 2.68 gallons per minute. This means you get on-demand hot water with no waiting or running out. The unit features an easy-to-use ON/OFF dial and a digital temperature display you can adjust to your preferred warmth. Its side 1/2 NPT water connections simplify installation, making it a practical fit for many homes.
- Power (Wattage or BTU):11,000 watts (11 kW)
- Voltage:240 Volts
- Flow Rate (Gallons Per Minute, GPM):Up to 2.68 GPM
- Temperature Range / Max Temperature:Not explicitly stated, but adjustable digital display
- Installation Type:Not explicitly stated, but implied wall-mounted
- Energy Efficiency / Technology:Self-modulating power control
- Additional Feature:ON/OFF dial control
- Additional Feature:Side 1/2 NPT connections
- Additional Feature:Self-modulating power control
110V Tankless Electric Water Heater 3000W Compact
People seeking a compact and efficient water heating solution will find the 110V Tankless Electric Water Heater 3000W Compact an excellent choice. This under-sink unit fits neatly in tight spaces, offering reliable hot water without the bulk of a traditional tank. Its clever design includes a temperature display that easily switches between Fahrenheit and Celsius, making it user-friendly for all preferences. Installation is straightforward, needing a circuit breaker of at least 32AMP and simple wiring with 1/2 NPT thread size. Being electric and tankless, it saves energy and cuts down on utility costs, all while reducing environmental impact.
- Power (Wattage or BTU):3,000 watts
- Voltage:110 Volts
- Flow Rate (Gallons Per Minute, GPM):Not explicitly specified, but compact under sink
- Temperature Range / Max Temperature:Not explicitly stated, but convertible display Fahrenheit/Celsius
- Installation Type:Compact under sink
- Energy Efficiency / Technology:Electric tankless design for energy efficiency
- Additional Feature:Convertible temperature scale
- Additional Feature:Requires ≥ 32AMP breaker
- Additional Feature:Compact footprint design
18kW Tankless Electric Water Heater WiFi Control
Homes looking for an efficient way to enjoy endless hot water without the hassle of bulky tanks will find the 18kW Tankless Electric Water Heater with WiFi control an excellent fit. This wall-mounted unit delivers up to 4.3 gallons per minute, enough for two to three water points in a home. Its smart self-regulating system adjusts power based on flow and temperature, saving energy while keeping water temperature stable. The WiFi feature allows remote control, so users can adjust settings from anywhere. Compact and safe, it uses 90% less space than traditional heaters and offers peace of mind with multiple protections.
- Power (Wattage or BTU):18,000 watts (18 kW)
- Voltage:240 Volts
- Flow Rate (Gallons Per Minute, GPM):Up to 4.3 GPM
- Temperature Range / Max Temperature:Maximum 140°F
- Installation Type:Wall-mounted
- Energy Efficiency / Technology:Self-regulating technology; up to 99% energy savings versus tanks
- Additional Feature:WiFi remote temperature control
- Additional Feature:Self-regulating power adjustment
- Additional Feature:ETL safety certified
Factors to Consider When Choosing Tankless Water Heaters
Upon selecting a tankless water heater, you’ll want to contemplate how much hot water you need at once, which means checking the flow rate capacity. Energy efficiency ratings also matter because they help you save on bills while being kind to the planet. Plus, don’t forget to take into account installation needs, temperature controls, and built-in safety features to keep everything running smoothly and safely.
Flow Rate Capacity
How much hot water can you expect from a tankless water heater? It all depends on its flow rate capacity, measured in gallons per minute (GPM). This number tells you how much hot water the unit can provide at once. In case you have several fixtures running simultaneously—like showers, sinks, or appliances—you’ll want a heater with a flow rate that matches your peak needs.
Small models handle about 0.3 to 3.1 GPM, perfect for a single sink or shower. Larger units, designed for whole-home use, deliver 4.4 GPM or more. Keep in mind, colder incoming water means the heater works harder, which can lower the flow rate at your desired temperature. Choosing the right flow rate helps you avoid chilly surprises during busy mornings.
Energy Efficiency Ratings
Picking the right flow rate is just one part of getting the most from your tankless water heater. You’ll want to check its energy efficiency ratings closely because these numbers tell you how well the heater converts fuel into hot water without wasting energy. Many tankless models reach an impressive 98% to 99.8% thermal efficiency, meaning they use almost all the energy they consume. Thanks to self-modulating technology, your heater adjusts power based on your hot water needs, saving as much as 50 to 60 percent on energy costs. Plus, tankless units only run whenever you need hot water, so you avoid standby energy loss common in traditional tanks. Some even offer digital controls with ±1°F precision, helping you avoid overheating and further enhancing efficiency.
Installation Requirements
Installing a tankless water heater involves more than just finding an ideal spot on the wall. You need to check whether your home’s electrical system can handle the unit’s power needs. For example, an 18kW heater could require a dedicated circuit with 75 amps and multiple breakers. Using the right wire gauge is essential too—usually 6 AWG for higher amps or 8 AWG for lower ones. Water connections typically use standard threaded fittings, so make sure to seal them well with Teflon tape to avoid leaks or shorts. Keep in mind some models must mount vertically to work properly. Also, verify your breaker panel has enough space and capacity to support the heater’s high current draw safely without overloading your system.
Temperature Control Options
Once your tankless water heater is safely installed and connected, controlling the water temperature becomes the next step in making your daily routine more comfortable. Many models come with digital thermostatic controls featuring LED displays, letting you adjust the temperature in precise increments—often within one degree. You can usually set the water anywhere from 80°F to 140°F, which fits most household needs.
Some heaters have easy-to-use dials right on the unit, while others use advanced tech that adjusts power based on flow and incoming water temperature to keep things steady. For extra convenience, WiFi-enabled models let you change settings remotely, so you can have perfect hot water ready before you even step into the shower. This level of control makes life simpler and more comfortable every day.
Safety Features Included
Because safety should always come foremost with any home appliance, choosing a tankless water heater means looking closely at the built-in protections it offers. You want features like leakage protection to avoid water damage and electrical hazards. Over-temperature protection is vital—it shuts off the heater in case the water gets too hot, keeping things safe.
Dry-boil protection also matters, powering down the unit once water flow stops to prevent damage. Many models include electrical isolation and waterproof ratings, like IPX4, which reduce shock risks and enhance durability. Plus, automatic power-off triggers react to overheating or long inactivity, adding extra peace of mind. Through focusing on these safety elements, you guarantee your heater runs smoothly while protecting your home and family without worries.
Warranty and Support
After making sure your tankless water heater has strong safety features, it’s just as vital to look at the warranty and support offered. A solid warranty often covers significant parts like the heat exchanger and electronics, sometimes lasting a lifetime for key components. But bear in mind, labor and incidental damages usually aren’t included, so check the fine print carefully.
Many brands also give you a satisfaction guarantee, typically 30 days, letting you return the unit in case it doesn’t meet your needs. On top of that, having easy access to expert technical support and clear online guides can make a big difference whenever troubleshooting or maintaining your heater. Finally, confirm any installation rules tied to the warranty to avoid surprises and keep your coverage intact.
