Over 65% of homeowners choose electric tankless water heaters for energy-efficient hot water on demand.
That’s why the Rheem series leads with models like the 18kW 240V and RTEX-24 24kW, delivering reliable, continuous hot water without bulky tanks.
Few realize these units also offer compact designs that save space while maintaining powerful performance.
Our review covers long-term value of these top Rheem heaters versus competitors in 2024.
How these water heaters measure up side-by-side
Compare the key features and specifications of our top picks to find the perfect match for your needs.
Rheem 18kW 240V Tankless Heater
Rheem 18kW 240V Tankless Electric Water Heater, Gray: Compact design, external digital thermostatic control with LED display, 240V power supply, durable copper immersion heating elements, 2-year warranty.
Benefits
- Flow rate up to 4.4 GPM provides continuous hot water for multiple applications without delay.
- Precise temperature control with +/- 1-degree accuracy via external digital LED display ensures consistent water temperature.
- Advanced self-modulation technology adjusts power usage to match hot water demand, enhancing energy efficiency and reducing utility costs.
- Durable copper immersion heating elements are field serviceable, extending the unit’s lifespan and simplifying maintenance.
- Simple installation with threaded bottom 3/4 inch NPT water connections enables easy replacement or upgrade of existing systems.
Drawbacks
- Requires 240V electrical connection,
- No internal water filter,
- Not ideal for very large households
A practical pick for homeowners seeking efficient, space-saving hot water solutions with precise temperature control and reliable performance in small to medium-sized residences.
Rheem 11kW 240V Tankless Heater
Rheem 11kW 240V Tankless Electric Water Heater: 12″ long, ABS plastic casing, 2-year warranty.
Benefits
- On-demand hot water with consistent and continuous flow, ideal for small households.
- Flow rate up to 2.68 GPM ensures sufficient hot water for single fixtures or light simultaneous use.
- Self-modulating power control optimizes energy use by adjusting power based on water flow, enhancing efficiency.
- Adjustable digital temperature display with ON/OFF dial control allows precise temperature settings up to desired comfort.
- Compact size (12″ long) fits easily in tight spaces, making it suitable for apartments or small homes.
- Durable ABS plastic housing provides corrosion resistance and a lightweight design.
Drawbacks
- Limited flow rate of 2.68 GPM may not suffice for multiple simultaneous uses in larger households.
- No dishwasher-safe parts as unit requires manual cleaning and maintenance.
- 240V power requirement may need electrical upgrades in older homes.
A practical pick for small spaces and users needing an efficient, compact electric tankless water heater for point-of-use applications.
Rheem RTEX-24 24kW Tankless Heater
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray: 12″ long, ABS plastic, 2-year warranty.
Benefits
- Provides continuous hot water suitable for whole home use, supporting multiple fixtures simultaneously.
- Energy-efficient design reduces electricity consumption by heating water on demand, eliminating standby heat loss.
- Adjustable digital temperature control with 1-degree increments from 80-140°F for precise comfort settings.
- Compact size saves space compared to traditional tank water heaters.
- No venting required, simplifying installation and increasing placement flexibility.
Drawbacks
- Requires significant electrical capacity: 3 x 40 AMP double pole breakers and a 200 AMP household service recommended, which may need panel upgrades.
- Installation complexity: Professional installation required to meet electrical specifications and local codes.
- Performance varies depending on ground water temperature and flow rate, potentially limiting temperature rise in colder climates.
A practical pick for homeowners seeking an energy-efficient, space-saving water heating solution with reliable whole-house performance, especially where upgrading electrical capacity is feasible.
ORBEK 14kW Electric Tankless Heater
14kW Tankless Water Heater Electric, ORBEK On Demand Instant Hot Water Heater 240V: 14.2″ H x 9.5″ L x 3.1″ W, ABS plastic exterior, 2-year warranty.
Benefits
- Delivers up to 3.38 gallons per minute (GPM) of continuous hot water, sufficient for 1-2 fixtures.
- Heats water instantly in approximately 3 seconds, reducing wait times significantly.
- Consumes up to 60% less electricity than traditional tank water heaters, providing notable energy savings.
- Advanced water-electricity separation technology minimizes scale buildup and corrosion for enhanced durability.
- Stable temperature control with adjustment of heating power 20,000 times per second, maintaining water temperature within 1°F.
- High-definition LED display allows precise temperature settings from 86°F to 140°F and real-time monitoring.
- Compact design saves over 50% space compared to conventional tank heaters, ideal for indoor, tight spaces.
- ETL certified and equipped with multiple safety protections including leakage, over-temperature, dry-heating, and lightning resistance.
Drawbacks
- Requires a dedicated 240V/60AMP two-pole breaker and proper electrical wiring (6 AWG wires), which may necessitate professional installation and additional electrical upgrades.
- Not suitable for households with circuit breaker panels under 150 amps total current capacity.
- Indoor use only; no outdoor installation option.
A practical pick for small spaces and users seeking an energy-efficient, reliable instant hot water solution for limited fixture demands.
110V 3000W Tankless Water Heater
110V Tankless Water Heater Electric, 3000W Tankless Electric Water Heater Instant, Under Sink Water Heater with Digital Display, On Demand Hot Water Heaters Electric for Kitchen Washin Bathroom: 12″ long, ABS plastic and stainless steel construction, 2-year warranty, 3000W power, digital LED display.
Benefits
- Rapid heating: raises water temperature by 82°F at 0.3 GPM and up to 131°F at 0.5 GPM in seconds.
- Compact size: 12″ length and wall-mounted design save valuable space under sinks or in tight areas.
- Energy efficient: thermal efficiency rated at 98%, reducing electricity consumption during use.
- Safety features: IPX4 waterproof rating, water and electricity isolation, leakage and dry boil protection, and automatic power off for overheating and inactivity.
- User-friendly digital display: allows temperature settings in Fahrenheit or Celsius, with intelligent status detection.
- Easy installation: pre-fabricated mounting holes and standard 1/2 inch NPT connections simplify setup.
- Durable materials: ABS plastic and stainless steel ensure longevity and corrosion resistance.
- Holds pressure for continuous flow without tipping or interruption.
Drawbacks
- No dishwasher-safe parts; cleaning requires manual effort and care.
- Limited flow rate (max 0.5 GPM) unsuitable for shower use or high-demand applications.
- Only supports vertical installation, restricting placement options.
- Requires 110V power supply with recommended wiring and trip switch specifications for safe operation.
A practical pick for small spaces such as apartments, kitchens, RVs, and bathrooms needing instant hot water on demand without bulky tanks.
Faq about best electric tankless water heater review:
1: What is an electric tankless water heater?
An electric tankless water heater heats water on demand, providing a continuous supply without storing hot water in a tank.
2: What are the benefits of using an electric tankless water heater?
Benefits include energy efficiency, space savings, and an endless supply of hot water, reducing heating costs over time.
3: How do I choose the best electric tankless water heater?
Consider factors like flow rate, energy efficiency ratings, installation requirements, and your household’s hot water needs.
4: Are electric tankless water heaters easy to install?
Installation can be straightforward for professionals, but DIY installation requires electrical knowledge and adherence to local codes.
5: How much can I save on energy bills with a tankless heater?
Users can save up to 30% on energy bills compared to traditional tank heaters, depending on usage patterns and efficiency.
6: Do electric tankless water heaters require maintenance?
Yes, regular maintenance such as descaling and checking electrical components can prolong the unit’s lifespan and efficiency.
Conclusion
The Rheem 18kW 240V model stands out for its robust heating capacity, ideal for households seeking rapid, continuous hot water without interruption. Its higher wattage ensures efficient performance under demanding conditions, making it suitable for larger homes or multiple simultaneous uses. On the other hand, the Rheem 11kW 240V offers a more compact, energy-conscious solution, perfect for smaller spaces or moderate hot water needs, balancing efficiency with cost-effectiveness.
Choosing between these two hinges on your specific requirements: prioritize the 18kW for powerful, high-demand applications, or opt for the 11kW to optimize energy consumption while maintaining reliable heating. Both models embody Rheem’s commitment to durability and advanced technology, guaranteeing satisfaction and long-term value in electric tankless water heating solutions.