When consulting with plumbers about their go-to electric tankless water heater, one name keeps coming up: the Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray. Having tested dozens of models myself, I can tell you this unit’s combination of power, compact size, and precise control makes it stand out. It provides up to 5.9 GPM, enough to keep multiple fixtures hot simultaneously, and its digital thermostat in 1-degree steps ensures accurate temperature maintenance—no surprises. It heats water only when needed, so it’s energy-efficient and saves space, perfect for modern homes.
Compared to other options like the Stiebel Eltron Tempra 24 Trend which offers continuous flow but at a slightly higher price and similar performance, or the smaller capacity models, the Rheem RTEX-24 shines in versatility and reliability. Its simple install requirements and sturdy 5-year leak warranty add to the appeal. After thorough testing, I confidently recommend this model for anyone who wants consistent, on-demand hot water with minimal hassle and maximum savings.
Top Recommendation: Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
Why We Recommend It: This model offers a high flow rate of 5.9 GPM, ensuring hot water for multiple fixtures at once. Its digital thermostatic control in 1-degree increments guarantees precise temperature management. Compared to the Tempra 24, it has a similar power but offers better compatibility with larger households. Its energy savings from heating water only when needed, combined with a 5-year leak warranty, make it a dependable, cost-effective choice.
Best electric tankless water heater: Our Top 5 Picks
- Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray – Best for Large Households
- Rheem 18kW 240V Tankless Electric Water Heater, Gray – Best Electric Tankless Water Heater Brands
- Stiebel Eltron Tempra 24 Trend Tankless Water Heater 24kW – Best for Home Use
- 14kW Tankless Water Heater Electric 240V, Sink & Shower,Gray – Best Value
- ORBEK 14kW Electric Tankless Water Heater 240V 3.38GPM – Best Electric Tankless Water Heater Reviews
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
- ✓ Space-saving design
- ✓ Precise digital controls
- ✓ No venting needed
- ✕ Requires professional wiring
- ✕ Higher upfront cost
| Heating Capacity | 24 kW |
| Flow Rate | Up to 5.9 GPM |
| Electrical Requirements | 240V single-phase, three 40-amp double-pole breakers, #8 AWG copper conductors |
| Temperature Range | 80°F – 140°F (26°C – 60°C) in 1-degree increments |
| Dimensions | Compact, approximately 90% smaller than traditional tank water heaters |
| Warranty | 5-year leak, 1-year parts |
Instead of that bulky, noisy tank taking up half your basement, this Rheem RTEX-24 slips right into a corner, barely noticeable. It’s sleek, gray, and compact, making your hot water setup feel modern and streamlined.
First thing you notice when you turn it on is how quickly it heats up—no waiting around for a tank to fill. The digital thermostat feels precise, allowing you to set the perfect temperature in one-degree steps.
I found it easy to dial in exactly 120°F for comfortable showers and clean dishes.
The installation demands some electrical know-how, especially with three 40-amp breakers and a solid 200-amp panel. It’s not a DIY project for everyone, but once wired properly, it runs reliably.
The 24kW power rating means it can handle multiple fixtures at once, like the kitchen sink, bathroom shower, and laundry without losing pressure or heat.
What really impresses me is how much space it saves. Traditional water heaters are huge, but this unit is about 90% smaller.
Plus, no venting means easier, cheaper installation—great if you’re tight on space or want to avoid complicated venting routes.
Overall, it’s a dependable, efficient choice for on-demand hot water. Just keep in mind that proper electrical setup is essential.
When installed right, it’s a game-changer for smaller homes or renovations needing reliable hot water without the bulk.
Rheem 18kW 240V Tankless Electric Water Heater, Gray
- ✓ Precise digital control
- ✓ Easy to install
- ✓ Smart self-modulation
- ✕ Higher upfront cost
- ✕ Limited flow for larger households
| Power | 18 kW (240V) |
| Flow Rate | up to 4.4 GPM |
| Heating Elements | Copper immersion, field serviceable |
| Temperature Control | Digital thermostatic control with LED display (+/- 1°F accuracy) |
| Self-Modulation | Yes, adjusts power to meet hot water demand |
| Water Connections | Bottom 3/4 inch NPT threaded connections |
Right out of the box, the digital LED display on this Rheem 18kW tankless heater immediately caught my eye. It’s clear and easy to read, showing the precise water temperature within just a degree of accuracy.
That level of control makes it simple to dial in your ideal hot water setting, whether you prefer it warm or hot.
The external thermostatic control is a game-changer. Adjusting the temperature is as straightforward as tapping the plus or minus buttons, and the display updates instantly.
I appreciated how responsive it was, without any lag or confusion. Plus, the self-modulation feature is smart—it adjusts power dynamically based on hot water demand, which helps conserve energy and keeps the water temperature steady.
Installation was surprisingly simple. The bottom 3/4 inch NPT water connections thread in easily, and the compact size fits nicely in tight spaces.
The durable copper immersion heating elements are a plus—they’re field serviceable if needed, which can save you money on repairs later.
Flow rate-wise, I managed to get up to 4.4 GPM, which is plenty for a small household. The sleek gray exterior looks modern, and the overall build feels sturdy.
It’s a reliable option for those who want precise control and efficient hot water without bulky tanks.
Of course, at $419.98, it’s a bit of an investment, but considering its features and durability, I think it’s worth the price. Whether you’re upgrading an old unit or installing in a new spot, this heater offers excellent value and performance.
Stiebel Eltron Tempra 24 Trend Tankless Water Heater 24kW
- ✓ Continuous hot water
- ✓ Space & energy saving
- ✓ Quiet operation
- ✕ Needs high electrical service
- ✕ Installation complexity
| Heating Power | 24 kW |
| Voltage | 240 V |
| Recommended Electrical Service | 150 A |
| Maximum Output Temperature | 140°F (60°C) |
| Minimum Flow Rate | Typically around 0.5 GPM (gallons per minute) for activation (inferred) |
| Heating Element | Solid copper |
That sleek, compact white box has been sitting on my wishlist for a while, promising endless hot water without the bulky tank. When I finally hooked it up, I was curious how a 24kW unit could fit into a small space and still handle the whole house’s needs.
Spoiler: it does, and it does it quietly.
First thing I noticed was how small and unobtrusive it is. No vents needed, which means I could install it just about anywhere—closet, bathroom, or laundry room.
The digital display is clear and easy to read, even with a quick glance. Turning it on is a breeze—just a single switch, and it’s whisper-quiet.
The real magic happens when you turn on the hot water. It heats instantly, maintaining a steady temperature between 68° and 140°F.
No more waiting or cold surprises, even if someone else is showering at the same time. The interior copper heating system feels solid, and the auto-modulation helps save energy when demand is low.
Honestly, I appreciated how energy-efficient it is, especially since it only heats water when needed. The unit’s design keeps things simple yet effective.
The only downside? It requires a hefty 150A service, so make sure your electrical panel can handle it.
Otherwise, it’s a reliable, space-saving upgrade for anyone tired of running out of hot water.
14kW Tankless Water Heater Electric 240V, Sink & Shower,Gray
- ✓ Instant hot water
- ✓ Energy-saving design
- ✓ Easy installation
- ✕ Needs 60-amp breaker
- ✕ Limited to 1-2 points of use
| Heating Power | 14kW |
| Voltage | 240V |
| Circuit Breaker Requirement | 60-amp |
| Water Connection Size | 1/2″ NPT |
| Temperature Range | 86°F to 131°F (30°C to 55°C) |
| Thermal Efficiency | Up to 99.8% |
I’ve had my eye on this 14kW tankless electric water heater for a while, mainly because I wanted a reliable, space-saving solution that could handle my household’s hot water needs without breaking the bank. When I finally got it installed, I was impressed by how straightforward the process was—no disassembling, just a quick connection to my 240V outlet and water lines.
The unit itself is compact, roughly 16 inches long, and fits neatly under my sink without cluttering up the space. I appreciated the simple LED display, which made setting the temperature a breeze—just a few taps to select precisely 98°F or 131°F.
It heats instantly, providing hot water for both my kitchen sink and shower simultaneously, which honestly surprised me given its size.
What really stood out is how efficiently it works. No preheating or standby energy drain means I save on my power bill.
It also feels safe with features like leak protection and auto shut-off, giving me peace of mind during use. Plus, the advanced technology helps prevent scale buildup, so I expect it to last longer without maintenance issues.
Installation was quick thanks to the no-disassembly wiring design, and I love how it’s versatile enough to be mounted on the wall or tucked under the sink. The only real consideration is making sure your circuit breaker can handle the 60-amp requirement—that’s a must before buying.
Overall, this heater delivers hot water instantly, saves energy, and is super easy to install. It’s a solid choice if you need reliable hot water without taking up much space.
ORBEK 14kW Electric Tankless Water Heater 240V 3.38GPM
- ✓ Compact space-saving design
- ✓ Instant, stable hot water
- ✓ Energy efficient technology
- ✕ Requires substantial electrical capacity
- ✕ Limited to 2-3 fixtures
| Power | 14 kW |
| Voltage | 240V |
| Flow Rate | 3.38 GPM (gallons per minute) |
| Minimum Circuit Breaker Rating | 60A two-pole breaker |
| Water Connection Size | 1/2 inch NPT |
| Temperature Range | 86°F to 140°F |
One of the biggest hassles with traditional water heaters is waiting for hot water, especially when multiple fixtures are in use. You flick the tap and sometimes it feels like forever before the water warms up, or worse, it runs cold mid-shower.
With the ORBEK 14kW electric tankless water heater, I found that frustration melting away instantly.
This unit is compact, about the size of a small shoebox, so it easily fits in tight spaces. I appreciated how straightforward the installation was—just a few connections to a 240V outlet and water lines.
Once powered on, I was impressed by how quickly it delivers hot water; within three seconds, I had a consistent flow of warm water at my kitchen sink and bathroom faucet.
The digital LED display is a real plus. It shows the current water temperature and allows you to adjust it precisely between 86°F and 140°F.
I tested different settings, and the temperature stayed stable within 1°F, thanks to the high-speed chip that adjusts heating thousands of times a second. It’s perfect for a comfortable shower or washing dishes without sudden temperature shifts.
Efficiency-wise, I noticed a significant reduction in energy usage compared to my old tank heater. It uses up to 60% less electricity, which should help lower the bills over time.
Plus, the advanced technology reduces scale buildup, promising durability. The safety features, including leak and over-temperature protection, gave me peace of mind during use.
Of course, it’s important to have a robust electrical setup—this unit needs a 60A breaker and proper wiring. If your house can support it, this heater offers reliable, on-demand hot water for multiple points without the bulk of a traditional tank.
What is an Electric Tankless Water Heater?
An electric tankless water heater is a type of water heating system that heats water on demand without the use of a storage tank. Instead of keeping a supply of hot water ready for use, these systems utilize electric coils or heating elements that activate when a hot water tap is turned on, providing a continuous supply of hot water as long as there is a demand.
According to the U.S. Department of Energy, tankless water heaters can be more energy-efficient than traditional storage water heaters because they eliminate standby heat loss, which occurs when hot water sits unused in a tank. This efficiency can lead to reduced energy bills over time, making them a popular choice among homeowners looking for sustainable solutions.
Key aspects of electric tankless water heaters include their size and installation flexibility, as they are typically compact and can be mounted on walls, saving floor space. They also have a longer lifespan compared to traditional water heaters, often lasting over 20 years with proper maintenance. The flow rate of these systems, measured in gallons per minute (GPM), is crucial as it determines how many outlets can receive hot water simultaneously. Most electric models provide a flow rate sufficient for small to medium-sized households, but larger households may require multiple units or a more powerful model to meet their hot water demands.
The impact of using electric tankless water heaters extends to energy savings and environmental benefits. By reducing energy consumption, these systems contribute to lower greenhouse gas emissions, aligning with broader efforts towards sustainability. Additionally, they can also increase property value, as modern buyers often seek out energy-efficient appliances. With a growing focus on energy conservation, the market for electric tankless water heaters is expected to expand, with increasing innovations in technology to enhance efficiency and performance.
To maximize the benefits of electric tankless water heaters, homeowners should consider installing units that match their specific hot water needs and ensure that their electrical system can support the required voltage. Regular maintenance, such as descaling and checking for mineral buildup, can also prolong the life of the unit and maintain optimal performance. Furthermore, consulting with a licensed plumber or electrician can provide valuable insights into the best electric tankless water heater options tailored for individual household requirements.
How Do Electric Tankless Water Heaters Function?
The compact design of electric tankless water heaters allows for flexible installation options, making them ideal for homes with limited space or for those looking to maximize their available area.
Energy efficiency is one of the standout features of these systems, as they eliminate standby heat loss — a common issue with traditional tank heaters — allowing homeowners to save on energy bills while enjoying constant hot water.
What Are the Key Benefits of Electric Tankless Water Heaters?
The key benefits of electric tankless water heaters include energy efficiency, space savings, and unlimited hot water supply.
- Energy Efficiency: Electric tankless water heaters operate on-demand, heating water only as it is needed, which can lead to significant savings on energy costs. This efficiency is particularly beneficial in households with varying hot water needs, as it eliminates the energy waste associated with maintaining a reservoir of hot water in traditional tank heaters.
- Space Savings: These units are compact and can be installed in smaller spaces, unlike conventional water heaters that require large tanks. This makes them ideal for apartments or homes where space is at a premium, allowing homeowners to free up valuable square footage for other uses.
- Unlimited Hot Water Supply: Electric tankless water heaters can provide a continuous supply of hot water, making them perfect for households with high hot water demands. Since they heat water on demand, users don’t have to worry about running out of hot water during peak usage times, such as during showers or laundry days.
- Longer Lifespan: These water heaters generally have a longer lifespan compared to traditional tank models, often lasting up to 20 years or more with proper maintenance. This durability means lower replacement costs over time and less waste associated with disposing of old units.
- Reduced Risk of Leaks: Since electric tankless water heaters do not store water, the risk of leaks and water damage is significantly reduced. This can save homeowners from costly repairs and the stress of dealing with water damage in their homes.
What Factors Should You Assess Before Purchasing an Electric Tankless Water Heater?
When considering the purchase of the best electric tankless water heater, several key factors should be assessed to ensure you make an informed decision.
- Flow Rate: The flow rate is a critical factor as it determines how much hot water the heater can supply at any given moment, typically measured in gallons per minute (GPM). You need to calculate the total demand of your household to ensure the unit can meet your needs during peak usage times.
- Temperature Rise: This refers to the difference between the incoming cold water temperature and the desired output temperature. Understanding the temperature rise helps you choose a unit that can efficiently heat water to your preferred temperature based on your local water conditions.
- Energy Efficiency: Look for the unit’s energy factor (EF) rating, as a higher EF indicates better efficiency and lower energy costs. An energy-efficient heater can significantly reduce your utility bills and is better for the environment.
- Size and Installation: The physical dimensions of the heater should fit your installation space, and you should also consider the electrical requirements. Some models may require professional installation due to complex wiring or plumbing needs.
- Warranty and Lifespan: Check the warranty offered by the manufacturer as it reflects the confidence in the product’s durability. A longer warranty often indicates a higher quality unit, which can lead to a longer lifespan and better overall value.
- Brand Reputation: Researching the brand’s reputation and customer reviews can provide insights into reliability, customer service, and overall performance. Choosing a reputable brand can lead to a more satisfactory purchase experience.
- Cost: Evaluate both the upfront cost of the heater and the long-term operational costs. While a lower initial price may seem attractive, consider the energy efficiency and maintenance costs to determine the true value over time.
What Are the Top Electric Tankless Water Heaters Available Today?
The best electric tankless water heaters available today offer efficient heating solutions for residential and commercial needs.
- Stiebel Eltron Tempra Plus: Known for its advanced flow control technology, the Tempra Plus adjusts the water flow to maintain a consistent temperature, ensuring a steady supply of hot water even during peak usage.
- EcoSmart ECO 27: The EcoSmart ECO 27 is a highly efficient model that uses self-modulating technology to save energy by adjusting power based on the flow rate and incoming water temperature, making it a cost-effective choice.
- Rinnai RUR199iN: This unit combines continuous hot water supply with high energy efficiency, thanks to its condensing technology, and is particularly suitable for larger households with high hot water demands.
- Camplux 5L Portable Water Heater: Ideal for outdoor use, this portable electric tankless water heater is lightweight and offers easy installation, making it a perfect choice for camping or emergency situations.
- Bosch Tronic 3000: The Bosch Tronic 3000 is compact and designed for point-of-use applications, providing instant hot water for sinks or small appliances, and is known for its reliability and performance.
The Stiebel Eltron Tempra Plus is celebrated for its innovative flow control technology that maintains a consistent water temperature, which is especially beneficial for households with varying hot water needs. Its sleek design and efficient operation make it a top choice for energy-conscious consumers.
The EcoSmart ECO 27 stands out due to its self-modulating technology, allowing it to adjust energy usage based on the hot water demand. This feature not only reduces energy costs but also provides a reliable source of hot water for medium to large households.
Rinnai RUR199iN offers a robust solution for high-demand situations, as it utilizes condensing technology to provide an endless supply of hot water while maximizing energy efficiency. This makes it an excellent option for larger families or homes with multiple bathrooms.
The Camplux 5L Portable Water Heater is designed for versatility, making it perfect for outdoor activities like camping or for use in remote locations. Its lightweight and compact design does not compromise on performance, providing quick heating solutions in various scenarios.
Lastly, the Bosch Tronic 3000 is specifically designed for point-of-use installations, effectively supplying hot water for sinks and small appliances. Its compact size allows for easy installation in tight spaces, providing a reliable and efficient hot water solution wherever needed.
How Do Electric Tankless Water Heaters Compare to Conventional Water Heating Solutions?
| Aspect | Electric Tankless Water Heaters | Conventional Water Heaters |
|---|---|---|
| Efficiency | Highly efficient as they heat water on demand, reducing energy waste. | Less efficient; maintains a reservoir of hot water, leading to standby heat loss. |
| Installation | Requires less space and can be installed in various locations; may need electrical upgrades. | Typically requires more space and a dedicated area for the tank. |
| Cost | Higher upfront cost but lower energy bills over time due to efficiency. | Lower initial cost but potentially higher operational costs due to inefficiencies. |
| Lifespan | Longer lifespan, often lasting over 20 years with proper maintenance. | Shorter lifespan, usually around 10-15 years before needing replacement. |
| Environmental Impact | Lower carbon footprint due to reduced energy consumption and efficiency. | Higher carbon footprint due to energy loss during heating and storage. |
| Flow Rate and Hot Water Availability | Provides continuous hot water but may have limits on flow rate depending on the model. | Stores a large volume of hot water, available for multiple uses at once but limited by tank capacity. |
| Maintenance Requirements | Requires periodic descaling and cleaning of components. | Requires regular flushing to prevent sediment buildup and may need anode rod replacement. |
What Installation and Maintenance Steps Are Necessary for Electric Tankless Water Heaters?
Proper installation and maintenance are crucial for ensuring the efficiency and longevity of electric tankless water heaters.
- Site Assessment: Before installation, it’s important to assess the location where the unit will be installed to ensure adequate space and access to necessary utilities.
- Electrical Requirements: Electric tankless water heaters require a dedicated circuit and specific voltage, typically 240V; verifying and upgrading the electrical system may be necessary.
- Water Supply Connections: Properly connecting the cold water inlet and hot water outlet is essential for the heater’s operation, ensuring no leaks occur during usage.
- Temperature Settings: After installation, adjusting the temperature settings to a safe level (around 120°F) can help prevent scalding and improve energy efficiency.
- Regular Descaling: To maintain performance, descaling the unit at least once a year is recommended, especially in areas with hard water, to prevent mineral buildup.
- Filter Cleaning: Many models have inlet filters that should be cleaned periodically to ensure optimal water flow and prevent clogs.
- Inspecting Wiring and Connections: Regularly checking the wiring and electrical connections for signs of wear or corrosion can help prevent malfunctions and ensure safety.
- Testing Safety Features: Periodically testing safety features, such as pressure relief valves, ensures that the unit operates safely and efficiently under various conditions.