Eemax vs Rheem Tankless Water Heaters: Which Brand Fits You?
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When you compare eemax vs rheem tankless water heater options, you see two electric brands with different strengths. Both units use electricity to heat water on demand. The main difference lies in their scale and power. Eemax offers a small point-of-use unit for single fixtures. Rheem provides a higher-capacity whole-house system. Your choice depends on whether you need heat for one sink or an entire home.
Key differences
| Aspect | Eemax FlowCo 3.5 kW 120V Point of Use Water Heater | Rheem 18kW 240V Electric Tankless Water Heater |
|---|---|---|
| Installation Location | Point of Use | Whole House |
| Wattage | 3.5 Kilowatt | 18 kW |
| Voltage | 120 Volt | 240 V |
| Flow Rate | 0.5 GPM (at 41°F rise) | Up to 4.4 GPM |
| Dimensions | 9.75 x 5 x 3 inches | 18.5 x 14.5 x 3.5 inches |
Which one should you choose?
Choose Eemax FlowCo 3.5 kW 120V Point of Use Water Heater if
- You need hot water for a single sink or small fixture.
- Your electrical panel only supports 120-volt circuits.
- You require a compact unit that mounts in tight spaces.
Choose Rheem 18kW 240V Electric Tankless Water Heater if
- You need to supply hot water for multiple fixtures simultaneously.
- You have a 240-volt electrical setup available.
- You want precise digital temperature control with LED display.
Verdict: Choose the Eemax unit if you need a compact, low-voltage solution for a single point of use. Select the Rheem model if you require higher flow rates and precise temperature control for whole-house applications.
Eemax vs Rheem: Key Differences
Power and Voltage
The Rheem unit operates at 240 volts with an 18 kW heating element. This high wattage allows it to handle significant hot water demands. In contrast, the Eemax model runs on 120 volts with only 3.5 kW of power. This lower voltage and wattage make the Eemax suitable for low-demand scenarios. You must ensure your electrical panel can support the higher amperage required by the Rheem system. The Eemax uses standard household wiring, which simplifies electrical requirements for small installations.
Flow Rate
Flow rate determines how much hot water you get at once. The Rheem heater delivers up to 4.4 gallons per minute. This capacity supports multiple fixtures or longer showers. The Eemax unit provides a temperature rise of 41°F at 0.5 gallons per minute. This low flow rate is intended for single sinks or handwashing. If you need hot water for a shower or tub, the Eemax flow rate is insufficient. The Rheem offers a much higher volume of usable hot water.
Installation Location
Installation location defines where each unit fits in your home. The Eemax is designed for point-of-use applications. Its compact dimensions of 9.75 x 5 x 3 inches allow it to mount under sinks or near specific fixtures. The Rheem unit is larger, measuring 18.5 x 14.5 x 3.5 inches. It is intended for whole-house installation. The Eemax can mount in any orientation, offering flexibility for tight spaces. The Rheem requires more wall space and is better suited for utility rooms or garages.
Temperature Control
Precision in water temperature affects your comfort and safety. The Rheem features an external digital thermostatic control with an LED display. It offers ±1°F accuracy, allowing you to set exact temperatures. The Eemax adjusts temperature based on flow rate rather than a digital dial. It lacks a digital display for precise setting adjustments. You get a temperature output based on the incoming water and flow. The Rheem provides more granular control over the final water temperature.
Build and Maintenance
Build quality and maintenance needs differ between the two brands. The Rheem uses durable copper immersion heating elements that are field serviceable. This design allows for easier repairs if issues arise. The Eemax includes self-diagnostics and intelligent controls to monitor operation. It also features SafeStart technology for added safety. The Eemax weighs only 3.1 pounds, making it very lightweight. The Rheem weighs 14.8 pounds, indicating a more robust internal construction. Both units are electric and require no venting.
Which Tankless Water Heater Fits Your Needs
Single sink or shower users with limited space
This Eemax unit measures just 9.75 by 5 by 3 inches. It mounts in any orientation, fitting tight spots under sinks. The 120-volt connection uses standard wiring. It heats water only when you turn the tap on. This compact design saves space while providing reliable hot water for one fixture.
Homeowners needing whole-house hot water supply
The Rheem model delivers up to 4.4 gallons per minute. Its 18-kilowatt power handles multiple simultaneous uses like showers and laundry. The 240-volt system supports higher demand. You get precise temperature control with LED display accuracy. This unit is built for whole-house needs rather than single-point applications.
Users wanting precise temperature adjustment and diagnostics
This Rheem heater features an external digital thermostat with plus or minus one degree accuracy. You can see the exact water temperature on the LED screen. The self-modulation adjusts power to match your flow rate. This technology ensures consistent heat output. You also benefit from field-serviceable copper heating elements for long-term reliability.
The products compared
Eemax FlowCo 3.5 kW 120V Point of Use Water Heater
Best for: Single sink point-of-use hot water
- Fuel Type
- Electric
- Wattage
- 3.5 Kilowatt
- Installation Location
- Point of Use
- Voltage
- 120 Volt
- Dimensions
- 9.75 x 5 x 3 inches
- Weight
- 3.1 pounds
View on Amazon: Eemax FlowCo 3.5 kW 120V Point of Use Water Heater Affiliate link
This Eemax unit is a compact, 120-volt electric water heater designed for point-of-use installation. It delivers 3.5 kilowatts of power, providing a 41°F temperature rise at 0.5 gallons per minute. Its small footprint, measuring 9.75 by 5 by 3 inches, allows for mounting in any orientation. You can install it under sinks or in tight spaces where a larger unit will not fit. It activates only when you need hot water.
Pros
- Compact dimensions of 9.75 x 5 x 3 inches
- Mounts in any orientation for flexible installation
- Self-diagnostics and intelligent controls
- SafeStart technology for operational safety
Cons
- Low 3.5 kW output limits flow rate
- Requires 120-volt electrical circuit
- Cold water inlet only
Good fit if
- You need hot water for a single sink
- You have limited space under a cabinet
- You want a point-of-use solution
Skip if
- You need hot water for multiple fixtures
- You require a higher flow rate
- You only have a 240-volt circuit
Verdict: Eemax 3.5kW 120V Point of Use Heater fits you if you need a small, dedicated heater for one sink. It does not work for whole-house needs or high-flow demands.
Rheem 18kW 240V Electric Tankless Water Heater
Best for: Precise temperature control in tight spaces
- Fuel Type
- Electric
- Flow Rate
- 4.4 GPM
- Wattage
- 18 kW
- Voltage
- 240 V
- Temperature Control
- ±1°F
- Dimensions
- 3.5 x 14.5 x 18.5 inches
View on Amazon: Rheem 18kW 240V Electric Tankless Water Heater Affiliate link
This Rheem unit delivers up to 4.4 GPM of hot water using 18 kW of power at 240 volts. It features external digital thermostatic control with LED display and ±1°F accuracy. The durable copper immersion elements are field serviceable. Its compact 3.5-inch height fits tight spaces. It suits whole-house needs where precise temperature control matters.
Pros
- 18 kW output provides up to 4.4 GPM flow rate
- External digital control with ±1°F temperature accuracy
- Compact 3.5-inch height for small installations
- Field serviceable copper immersion heating elements
Cons
- Requires 240V electrical circuit
- 14.8 lbs weight adds mounting load
- No remote control listed in specifications
Good fit if
- You need precise temperature control within 1°F
- You have a 240V electrical supply available
- You require a compact unit under 4 inches tall
Skip if
- You only have 120V outlets
- You need more than 4.4 GPM simultaneous flow
- You prefer gas-powered heating systems
Verdict: Rheem 18kW Electric Tankless Water Heater fits homes needing precise hot water delivery in tight spaces. It works best for users with 240V power who value accurate temperature settings.
Specifications side by side
| Spec | Eemax FlowCo 3.5 kW 120V Point of Use Water Heater | Rheem 18kW 240V Electric Tankless Water Heater |
|---|---|---|
| Fuel Type | Electric | Electric |
| Flow Rate | not stated | 4.4 GPM |
| Wattage | 3.5 Kilowatt | 18 kW |
| Installation Location | Point of Use | not stated |
| Voltage | 120 Volt | 240 V |
| Temperature Control | not stated | ±1°F |
| Dimensions | 9.75 x 5 x 3 inches | 3.5 x 14.5 x 18.5 inches |
| Use | not stated | Whole House |
| Weight | 3.1 pounds | 14.8 pounds |
| Color | White | Gray |
| Model | SPEX3512 | RTEX-18 |
| Size | not stated | Small |
Frequently asked questions
Can the Eemax FlowCo heater replace a whole-house unit?
No. This Eemax model is designed strictly for single sink point-of-use applications. It lacks the power for whole-house needs or high-flow demands. If you require hot water for multiple fixtures or a shower, this 3.5 kW unit will not meet your capacity requirements.
Does the Rheem RTEX-18 require special wiring?
Yes. The Rheem unit operates on 240 volts with an 18 kW heating element. This high wattage demands a dedicated circuit and appropriate electrical infrastructure. You must ensure your home has the necessary 240V power supply before installation to handle the significant hot water demands.
Which brand is better for tight under-sink spaces?
Eemax fits better here. The FlowCo model measures just 9.75 by 5 by 3 inches. It mounts in any orientation, fitting tight spots under sinks. The Rheem unit is larger at 18.5 inches long, making it less suitable for confined cabinet spaces.
What is the weight difference between these two heaters?
The Eemax unit is significantly lighter. It weighs 3.1 pounds, making it easy to handle and mount. The Rheem model weighs 14.8 pounds. This added weight reflects its higher capacity and robust construction for whole-house electric heating applications.
Can I use the Eemax heater for a shower?
No. The Eemax FlowCo is a 3.5 kW point-of-use heater. It is not designed for the high-flow demands of a shower. It is intended for single sink applications where low flow rates are acceptable for maintaining consistent hot water temperature.
Is the Rheem heater suitable for precise temperature control?
Yes. The Rheem 18 kW unit is noted for precise temperature control in tight spaces. It works best for users who value accurate temperature settings. The 240V power supply supports stable heating performance for consistent delivery throughout your home.
What color options are available for these models?
The Eemax FlowCo is white. The Rheem RTEX-18 is gray. These color choices allow you to select a unit that blends with your existing decor or utility space. The exterior finish is durable for standard indoor installation environments.