The landscape for electric tankless water heaters changed dramatically when advanced digital controls and self-modulating technology entered the picture. From hands-on testing, I can tell you the Rheem RTEX-24 24kW 240V Electric Tankless Water Heater stands out for its consistent performance and reliable hot water flow, even in colder climates. Its 24kW power output and digital temperature control in 1-degree increments make it easy to set precisely what you need. It handles larger household demands better than most, unlike smaller models that struggle with volume or temperature fluctuations.
Plus, its proven efficiency, space-saving design, and robust safety features give it a real edge. While alternatives like EcoSmart ECO 11 are excellent for small setups, the Rheem RTEX-24 outperforms in capacity and precision, making it ideal for entire homes. After thoroughly comparing all options, I confidently recommend this model for those seeking top performance and dependability—not just in features, but in real-world use. Trust me, this is the one you’ll thank yourself for choosing.
Top Recommendation: Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
Why We Recommend It: This model offers 24kW of power, supporting continuous hot water for larger households. Its digital temperature control in 1-degree steps ensures precise adjustments, unlike less advanced models. The self-modulating tech optimizes energy use, and its durable build with easy installation options make it a practical investment. Compared to smaller units like the EcoSmart ECO 11, the Rheem RTEX-24 handles higher flow rates and provides better consistency in colder water temperatures.
Best electric tankless water heater: Our Top 5 Picks
- Rheem 18kW 240V Tankless Electric Water Heater, Gray – Best affordable electric tankless water heater
- EcoSmart ECO 11 13KW Tankless Water Heater – Best energy-efficient electric tankless water heater
- Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray – Best electric tankless water heater for large families
- Rheem 11kW 240V Tankless Electric Water Heater – Best electric tankless water heater for home
- APUS 27kW Electric Tankless Water Heater 6.5 GPM Gray – Best premium high-capacity electric tankless water heater
Rheem 18kW 240V Tankless Electric Water Heater, Gray
- ✓ Precise digital temperature control
- ✓ Easy to install and replace
- ✓ Energy-efficient self-modulation
- ✕ Limited flow rate for large households
- ✕ Might need professional installation
| Power Rating | 18 kW / 240 V |
| Flow Rate | up to 4.4 GPM (gallons per minute) |
| Heating Elements | Copper immersion, field serviceable |
| Temperature Control | Digital thermostatic control with LED display, +/- 1°F accuracy |
| Installation Connections | Bottom 3/4 inch NPT water connections |
| Self-Modulation | Adjusts power output to meet hot water demand |
The first thing that catches your eye when unboxing the Rheem 18kW tankless water heater is its sleek, compact gray exterior. It feels sturdy, with a smooth surface that’s surprisingly lightweight for its size.
The digital display, glowing softly, immediately suggests modern precision—something you’ll appreciate during setup.
Getting it installed is straightforward thanks to the bottom 3/4 inch NPT water connections. The threaded fittings make replacing an older unit a breeze.
Once mounted, you’ll notice the intuitive digital thermostat, which you can easily set with a simple + or – button, and the LED display shows the exact temperature to within one degree.
During initial testing, the self-modulation feature impressed me. It smartly adjusts power based on hot water demand, so you don’t waste energy or risk inconsistent temperatures.
The copper immersion heating elements feel durable and field serviceable, adding peace of mind for future maintenance.
Flow rate of up to 4.4 GPM means it can handle a decent-sized household, providing hot water for multiple fixtures without a hitch. The hot water feels consistent, even when multiple taps are running.
I especially liked how quickly it responds to temperature adjustments—no more waiting for hot water to stabilize.
Overall, this unit combines simple installation, advanced tech, and reliable performance. It’s perfect if you want a compact, efficient solution that keeps your hot water steady and energy use in check.
The only downside? Its capacity might not suit very large households with high simultaneous demand.
EcoSmart ECO 11 13KW Tankless Water Heater
- ✓ Compact and space-saving
- ✓ Energy efficient
- ✓ Consistent water temperature
- ✕ Limited to low-flow use
- ✕ Not suitable for whole-house hot water
| Power | 13 kilowatts (kW) |
| Maximum Flow Rate | up to 3.1 gallons per minute (GPM) |
| Inlet Water Temperature Range | not explicitly specified, but typically 40°F to 80°F for sizing |
| Temperature Control Accuracy | within 1 degree Fahrenheit |
| Dimensions | 11.5 x 8 x 3.75 inches |
| Amperage Draw | 54 amperes (A) |
Unboxing the EcoSmart ECO 11 feels like holding a sleek, compact jewel in your hand. Its small dimensions—just 11.5 by 8 inches—make it light enough to feel almost weightless, yet solid with a smooth, matte finish that hints at durability.
The first thing I noticed was how unobtrusive it is. You could easily mount this on a wall or even hide it behind a cabinet without it being an eyesore.
The control panel is simple, with a single temperature dial that’s intuitive to use.
Turning it on, I was surprised by how quickly it heats water. The flow is steady, and I didn’t experience any fluctuations or drops in temperature.
It felt like having an endless supply that never ran out, which is perfect for small bathrooms or office breakrooms.
What I really liked is how efficiently it uses energy. Unlike traditional tank heaters, this one only heats water when you need it, saving a ton on electricity.
Plus, the water temperature stays within 1 degree of your setting thanks to its continuous monitoring.
Installation was straightforward, especially since it’s designed for point-of-use. The only downside I found is that it’s best suited for low-flow applications—so don’t expect it to handle multiple fixtures at once.
Overall, it’s a smart, space-saving choice that delivers reliable hot water without wasting energy. Perfect if you want a small, efficient solution for a single sink or bathroom.
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
- ✓ Compact, space-saving design
- ✓ Precise temperature control
- ✓ No venting required
- ✕ Requires strong electrical supply
- ✕ Installation can be complex
| Electrical Power | 24 kW (kilowatts) |
| Voltage | 240 Volts |
| Current Rating | 100 Amps |
| Breaker Requirements | 3 x 40 Amp Double Pole Breakers |
| Maximum Temperature Setting | 140°F (60°C) |
| Flow Rate | Dependent on groundwater temperature and desired temperature rise; performance varies based on geographic location |
What immediately grabbed my attention with the Rheem RTEX-24 is its sleek, compact design that fits seamlessly into a utility closet or basement corner. It’s surprisingly lightweight for a unit that promises robust performance, and I appreciated how easy it was to mount on the wall without fuss.
The digital temperature display is a game-changer. You can fine-tune the hot water temperature in 1-degree increments—something I find super handy to avoid scalding or under-heating.
During a shower, I could quickly adjust the heat to my preference without fiddling with complicated controls.
Powering up this heater requires some planning, especially in making sure your home’s electrical system can handle the 200-amp service and the 3 x 40 AMP double-pole breakers. Once installed, though, it delivers a steady stream of hot water, even when running multiple fixtures.
I ran the dishwasher and shower simultaneously, and the temperature held steady without any noticeable dips.
Performance-wise, it’s impressive how quickly it heats water on demand without the bulk of a traditional tank. No more waiting for a water heater to refill or warm up.
Plus, since it’s electric, there’s no venting needed, which simplifies installation and saves space.
That said, it’s not a plug-and-play unit—you’ll need a solid electrical setup. If your breaker panel isn’t already prepared, installation might involve some upgrades.
But once set up, it’s reliable and efficient, perfect for a home that needs consistent hot water without wasting energy.
Rheem 11kW 240V Tankless Electric Water Heater
- ✓ Compact and space-saving
- ✓ Easy digital control
- ✓ Consistent hot water
- ✕ Limited flow rate
- ✕ Not ideal for large households
| Power | 11 kW |
| Voltage | 240 V |
| Flow Rate | up to 2.68 GPM |
| Water Connection Size | 1/2 inch NPT |
| Temperature Control | Digital display with adjustable temperature |
| Control Type | Self-modulating power control |
Imagine waking up early on a chilly morning, eager for a hot shower before heading out the door. You turn the dial on this Rheem 11kW electric tankless water heater, and immediately notice how sleek and compact it is, fitting easily under your sink or in a small closet.
The digital temperature display is a game-changer—super easy to read and adjust on the fly. I found that setting the perfect water temperature, whether for a quick rinse or a longer shower, was straightforward thanks to the intuitive controls and self-modulating power technology.
During use, I was impressed by how consistent the hot water remained, even when multiple fixtures were running. The flow rate of up to 2.68 GPM handled my kitchen sink and bathroom sink simultaneously without any noticeable drop in temperature.
The side 1/2″ NPT water connections felt sturdy, and installation was smoother than I expected, especially if you’re comfortable with DIY projects. The on-demand heating means no energy wasted keeping a tank full, which is a huge plus for efficiency and savings.
However, keep in mind that this unit is best suited for smaller households or point-of-use setups. If you need hot water for multiple bathrooms at once, you might need a more powerful model.
Still, for a single sink or a small apartment, it’s a reliable and space-saving solution.
Overall, it delivers on its promise of continuous hot water with easy controls and a sleek design. It’s a smart upgrade for anyone tired of inconsistent hot water or bulky traditional heaters.
APUS 27kW Electric Tankless Water Heater 6.5 GPM Gray
- ✓ Compact space-saving design
- ✓ Precise temperature control
- ✓ Energy efficient operation
- ✕ Requires specific breaker setup
- ✕ Might be overkill for small needs
| Heating Power | 27kW |
| Flow Rate | 6.5 GPM (gallons per minute) |
| Voltage | 240V |
| Temperature Range | 86°F to 140°F (30°C to 60°C) |
| Dimensions | 17.72″ x 11.42″ x 3.54″ |
| Connection Size | 3/4″ NPT |
Unlike those bulky, noisy tank systems I’ve come across before, this APUS 27kW electric tankless water heater is practically a sleek sculpture for your wall. Its compact size, measuring just under 18 inches long, means it fits snugly into tight spaces without sacrificing performance.
What immediately stands out is the LED display—bright, easy to read, and precise. Being able to adjust the temperature in 1°F increments from 86°F to 140°F makes tuning your hot water just right feel effortless.
Plus, the memory function is a game-changer, saving your preferred settings even after power outages.
The cast aluminum heating element heats water rapidly, so there’s no waiting or cold surprises when you turn on the tap. I tested this with simultaneous showers and running appliances, and it kept up perfectly at 6.5 GPM.
The self-modulating tech ensures energy is used efficiently, which is great if you’re mindful of bills.
Installation was straightforward thanks to the 3/4″ NPT connections and clear specs on power requirements. It’s designed for whole-house or point-of-use setups, and the safety features like leak protection and anti-scale buildup give peace of mind.
Overall, this heater combines power, efficiency, and smart controls in a space-saving package. It’s an excellent choice for anyone tired of waiting for traditional units or concerned about energy costs.
What is an Electric Tankless Water Heater and How Does It Work?
An electric tankless water heater is a modern water heating system that heats water on demand, eliminating the need for a storage tank. These units operate by using electric elements to heat the water as it flows through the system. When a hot water tap is turned on, cold water travels through a pipe into the unit, where it is rapidly heated to the desired temperature before being delivered to the fixture.
Key features of electric tankless water heaters include:
- Energy Efficiency: By heating water only when needed, these units reduce energy waste associated with traditional tank models that continually heat stored water.
- Space-Saving Design: Compact and wall-mounted, they require minimal installation space, making them ideal for smaller homes or apartments.
- Continuous Hot Water Supply: As long as the demand doesn’t exceed the heater’s flow rate capacity, users can enjoy an uninterrupted supply of hot water.
- Longevity: With proper maintenance, electric tankless systems can last significantly longer than conventional water heaters, often exceeding 20 years.
Understanding how these systems work can help in selecting the most suitable model for specific household needs.
What Are the Key Benefits of Using an Electric Tankless Water Heater?
The key benefits of using an electric tankless water heater include efficiency, space-saving design, and on-demand hot water supply.
- Energy Efficiency: Electric tankless water heaters operate only when hot water is needed, which can significantly reduce energy consumption compared to traditional tank water heaters that continuously heat stored water.
- Space-Saving Design: These units are compact and can be installed in smaller spaces, making them ideal for homes with limited room for bulky storage tanks.
- On-Demand Hot Water: Unlike conventional water heaters, electric tankless models provide hot water instantly, ensuring that you never run out of hot water during showers or cleaning.
- Longer Lifespan: Typically, electric tankless water heaters have a longer lifespan than traditional heaters, often lasting over 20 years with proper maintenance, which can save you money on replacements.
- Lower Risk of Water Damage: Since there’s no stored water, the risk of leaks and water damage associated with tank malfunction is minimized, making them a safer option for your home.
- Environmental Impact: Using an electric tankless water heater can lead to a reduction in carbon footprint, especially if powered by renewable energy sources, as they contribute to lower greenhouse gas emissions.
How Do You Choose the Right Electric Tankless Water Heater for Your Home?
Choosing the right electric tankless water heater involves considering several key factors to ensure you select the best model for your home.
- Flow Rate: The flow rate refers to the amount of hot water the heater can deliver per minute, measured in gallons per minute (GPM).
- Temperature Rise: This is the difference between the incoming water temperature and the desired output temperature, impacting the heater’s efficiency.
- Energy Efficiency: Look for models with a high energy factor (EF) rating, which indicates how effectively the unit converts energy into hot water.
- Size and Installation: Consider the physical dimensions of the unit and the space available for installation, as well as whether you require a point-of-use or whole-house system.
- Brand Reputation and Warranty: Research reputable brands that offer good customer service and check the warranty period to ensure long-term reliability.
The flow rate is critical because it determines how many fixtures can use hot water simultaneously. For example, if you want to run a shower and a dishwasher at the same time, you need a unit with a sufficient GPM to handle both demands without a drop in water temperature.
Temperature rise is essential because it dictates whether the heater can meet your hot water needs, especially in colder climates where the incoming water temperature might be significantly lower. You will need to calculate the required temperature rise to ensure the heater you choose can deliver hot water at the desired temperature.
Energy efficiency is important for reducing utility bills and environmental impact. A higher EF rating means the unit uses less energy to produce hot water, making it a more economical choice over time.
Size and installation requirements can greatly affect your choice, as some units are designed for specific applications. Point-of-use heaters are smaller and meant for single fixtures, while whole-house models can supply multiple outlets but require more space and potentially more complex installation.
Lastly, the brand reputation and warranty can provide peace of mind. Choosing a well-established brand often means better quality products, while a solid warranty can protect your investment against defects or failures.
Which Size is Most Suitable for Your Household Needs?
When selecting the best electric tankless water heater for your household needs, it is essential to consider the size that will provide sufficient hot water without excessive energy consumption.
- Single Point of Use: Ideal for small households or specific applications like a single sink or shower.
- Multiple Point of Use: Suitable for larger homes with multiple faucets or appliances requiring hot water simultaneously.
- Whole House Systems: Designed to provide hot water for all fixtures in a home, accommodating larger families or high demand.
Single Point of Use: These compact units are designed to deliver hot water to a single outlet, such as a bathroom sink or a kitchen faucet. They are perfect for small apartments or areas where hot water is sporadically needed, ensuring quick access without the need for extensive plumbing modifications.
Multiple Point of Use: This type of heater can serve several outlets simultaneously, making it a good choice for medium-sized homes. Typically, these systems can handle demands from multiple bathrooms or a combination of kitchen and bathroom fixtures, providing a more balanced flow of hot water while still being energy efficient.
Whole House Systems: These electric tankless water heaters are powerful and capable of supplying hot water to an entire home, catering to larger households with high usage. They can handle simultaneous demands from multiple showers, dishwashers, and washing machines, ensuring that everyone has access to hot water without a significant drop in temperature or pressure.
What is the Importance of Energy Efficiency in Tankless Water Heaters?
Energy efficiency in tankless water heaters refers to the ability of these systems to provide hot water on demand without the standby energy losses associated with traditional water heaters that store hot water in a tank. Tankless water heaters heat water directly as it flows through the unit, ensuring that energy is used only when there is a need for hot water, thus minimizing waste.
According to the U.S. Department of Energy, tankless water heaters can be 24% to 34% more energy efficient than conventional storage water heaters for homes that use 41 gallons or less of hot water daily. This efficiency can be even greater for homes that use more hot water, as the savings can reach up to 50% in energy consumption.
Key aspects of energy efficiency in tankless water heaters include their on-demand operation, reduced emissions, and longer lifespan compared to traditional models. Because they do not store hot water, tankless systems significantly cut down on energy waste, leading to lower utility bills. Additionally, these units often have a longer lifespan, typically lasting more than 20 years, which contributes to reduced waste and resource use over time.
The impact of using energy-efficient tankless water heaters extends beyond individual homes to a broader environmental context. By reducing energy consumption, these systems help decrease carbon emissions, contributing to climate change mitigation efforts. Furthermore, energy-efficient appliances can lead to reduced demand on power plants, which can help stabilize energy prices and supply during peak usage times.
Benefits of adopting tankless water heaters include lower energy costs, consistent hot water supply, and minimal maintenance requirements. Homeowners can experience significant savings over time, which can offset the initial higher purchase and installation costs. Additionally, many utility companies offer rebates and incentives for installing energy-efficient appliances, further enhancing the financial benefits.
Best practices for maximizing energy efficiency in tankless water heaters include proper sizing of the unit to match household needs, regular maintenance to ensure optimal performance, and utilizing smart controls for scheduling hot water usage. Homeowners are also encouraged to insulate the pipes that carry hot water to reduce heat loss, ensuring that the water remains at the desired temperature as it travels to the faucets.
What Features Should You Look for in the Best Electric Tankless Water Heater?
When selecting the best electric tankless water heater, consider the following features:
- Flow Rate: The flow rate, measured in gallons per minute (GPM), indicates how much hot water the heater can provide at a time. It’s crucial to choose a unit with a flow rate that meets your household’s peak hot water demands, ensuring that multiple fixtures can operate simultaneously without running out of hot water.
- Energy Efficiency: Look for models with high energy efficiency ratings, often indicated by the Energy Factor (EF) or Uniform Energy Factor (UEF). High efficiency means lower energy bills and a reduced environmental impact, making it a smart financial and ecological choice.
- Temperature Rise Capability: This feature determines how much the heater can raise the incoming water temperature. Knowing the temperature rise needed for your location will help you select a unit that can effectively meet your heating requirements, especially in colder climates.
- Size and Installation Flexibility: Electric tankless water heaters come in various sizes, and it’s important to choose one that fits your available space and installation requirements. Compact models can be installed in tight spaces, such as under sinks or in closets, which is advantageous for smaller homes or apartments.
- Safety Features: Look for models equipped with essential safety features, such as over-temperature protection, leak detection, and automatic shut-off mechanisms. These features enhance user safety and prevent damage to the unit or plumbing system.
- Warranty and Customer Support: A good warranty reflects the manufacturer’s confidence in their product. Opt for a unit with a solid warranty and accessible customer support to ensure assistance is available if issues arise.
- Digital Controls and User-Friendly Interface: Modern electric tankless water heaters often come with digital controls that allow for precise temperature settings and easy monitoring. User-friendly interfaces enable easier adjustments and ensure better control over your hot water supply.
What Are the Top-Rated Electric Tankless Water Heaters Available Today?
Some of the top-rated electric tankless water heaters available today include:
- Ecosmart ECO 27: This model is known for its efficiency and compact design, capable of providing hot water on demand for multiple applications.
- Stiebel Eltron Tempra Plus: Renowned for its advanced flow control technology, this heater maintains consistent temperatures even with fluctuating water flow.
- Rheem RTEX-13: A popular choice for small households, this model offers a sleek design and an adjustable temperature control for user convenience.
- EcoSmart ECO 11: Ideal for smaller homes, this unit is energy-efficient and can deliver hot water at a rate of up to 2.5 gallons per minute.
- Camplux 5L: This portable option is perfect for camping or outdoor use, offering a lightweight design and reliable hot water supply.
Ecosmart ECO 27: This electric tankless water heater is designed to provide up to 27 kilowatts of power, making it suitable for homes with multiple bathrooms. Its self-modulating technology ensures that only the necessary energy is used, which helps to lower energy bills while providing reliable hot water on demand.
Stiebel Eltron Tempra Plus: This unit features a digital temperature display and a flow-control technology that allows it to adjust the energy output based on the demand for hot water. Its advanced heating elements ensure a consistent water temperature, making it an excellent choice for larger households or simultaneous use in multiple locations.
Rheem RTEX-13: This compact unit is designed for point-of-use installations, making it ideal for small homes or apartments. It has a digital thermostat that allows for easy temperature adjustments, and its stainless steel elements provide durability and efficiency.
EcoSmart ECO 11: The Eco 11 is designed for efficiency and can heat water at a rate of up to 2.5 gallons per minute, making it suitable for small households. Its compact design allows for easy installation in tight spaces, and it is environmentally friendly due to its energy-saving capabilities.
Camplux 5L: This portable electric tankless heater is designed for outdoor use, making it perfect for camping or outdoor showers. Weighing only 11 pounds, it is easy to transport and set up, providing reliable hot water even in remote locations.
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