6 Best Alternatives to the NOVIEEX 18kW Tankless Water Heater (2026)

How the alternatives compare

Thermomate 18kW Electric Tankless Water Heater

The Thermomate 18kW matches the NOVIEEX power at 18 kW and 240V for similar whole-house performance. It differs in physical size, measuring 13.1 inches wide and 17.1 inches tall, which is larger than the NOVIEEX’s 11.14-inch width. This model uses self-modulating technology to adjust heat output, providing steady temperature control. You get a gray finish instead of silver. It is a solid choice if you prioritize consistent digital regulation over the ultra-thin profile of the NOVIEEX. The larger footprint may require more wall space in tight utility closets. It suits buyers who want reliable whole-house flow with precise heat management.

ThermoMate 14kW Electric Tankless Water Heater

The Thermomate 14kW offers a lower power option at 14 kW, making it suitable for smaller homes or tighter electrical budgets. It shares the 240V requirement but delivers less total heating capacity than the 18 kW NOVIEEX. Its dimensions are 11.2 inches wide and 15.9 inches tall, closely matching the NOVIEEX’s footprint but weighing only 13 pounds. This unit is ideal for users who prioritize space savings and safety certification over maximum flow rate. You sacrifice some simultaneous fixture capacity for a more compact and lighter installation. It fits well in small apartments or condos where electrical infrastructure is limited. Choose this if you need a reliable, efficient solution for light-to-medium hot water use.

Ranein 18kW 4.3 GPM Electric Water Heater

The Ranein 18kW provides 4.3 GPM flow, which is slightly lower than the NOVIEEX’s 4.9 GPM. It maintains the same 18 kW power and 240V requirement, ensuring similar heating intensity. The unit is larger, measuring 13.8 inches wide and 18.7 inches tall, and weighs 17.4 pounds. It features certified safety mechanisms and precise temperature management for whole-house use. You give up a small amount of flow capacity for a robust build. This model suits households needing reliable hot water for showers and sinks without the highest possible GPM. It is a good alternative if you prefer a slightly different form factor and value certified safety features over the absolute maximum flow rate.

WINTEMP 18 kW Tankless Water Heater with WiFi

The WINTEMP 18kW includes WiFi connectivity, allowing remote temperature control via an app. It matches the 18 kW power and 240V requirement of the NOVIEEX. Its dimensions are unique, measuring 11.1 inches wide but only 4 inches tall, with a length of 19.1 inches. This slim vertical profile saves wall space differently than the NOVIEEX. You gain smart control features that the NOVIEEX does not offer. The unit weighs 12 pounds, making it relatively light. It suits buyers who need precise remote adjustments and have the necessary electrical infrastructure. The WiFi capability adds convenience for monitoring and adjusting settings from anywhere. Choose this if smart home integration is a priority for your hot water system.

Orbek 18kW 240V Tankless Electric Water Heater

The Orbek 18kW is significantly more compact, measuring only 8 inches wide and 11 inches tall. It shares the 18 kW power and 240V requirement, delivering reliable whole-house hot water. Its snow-colored finish and compact size make it ideal for tight spaces. You get a smaller footprint than the NOVIEEX, which is 11.14 inches wide. This model suits users who value certified safety and a minimalist design. It may not offer the same flow rate as the NOVIEEX, but it provides efficient heating in a small package. Choose this if wall space is limited and you need a dependable electric tankless heater. The compact dimensions allow for flexible installation in small utility areas or closets.

SIVUATEK 18 kW Electric Tankless Water Heater

The SIVUATEK 18kW offers strong flow and safety features for whole-house use. It matches the 18 kW power and 240V requirement. Its dimensions are 11 inches wide and 3 inches tall, with a length of 15 inches. It weighs 19 pounds, making it heavier than the NOVIEEX. This model focuses on consistent temperature and space-saving design without smart connectivity. You get a robust build with high electrical capacity support. It suits users who prioritize steady hot water performance over WiFi features. The compact height allows for easy mounting. Choose this if you need a reliable, high-capacity heater with a focus on durability and consistent output. It is a solid alternative for homes with adequate electrical infrastructure.

Quick picks

Our 7 picks

1 Best overall

NOVIEEX 18 kW 4.9 GPM Tankless Water Heater

Best for: Small homes needing high flow and precise heat

Fuel Type

Electric

Flow Rate

4.9 GPM

Wattage

18kW

Installation Location

Indoor

Voltage

240V

Temperature Control

77°F to 140°F, 1°F increments

View on Amazon: NOVIEEX 18 kW 4.9 GPM Tankless Water Heater

This 18kW electric unit delivers up to 4.9 GPM at 240V, making it suitable for small-to-medium homes with two to three simultaneous water needs. It features precise temperature control from 77°F to 140°F in 1°F increments. The compact design mounts on the wall to save space. It includes an LED display and an 8-layer safety system. This model suits households prioritizing high flow and adjustable heat.

Pros

• High flow rate of 4.9 GPM for multiple fixtures
• Precise 1°F temperature adjustments from 77°F to 140°F
• 99.8% thermal efficiency eliminates standby energy waste
• Compact wall-mount design saves space compared to storage tanks

Cons

• Requires 2x40A circuit breakers and 8 AWG wiring
• Indoor installation only
• 1-year warranty is shorter than lifetime technical assistance

Good fit if

• You need high flow for 2-3 simultaneous water points
• You want precise temperature control in 1°F steps
• You have the electrical capacity for 2x40A breakers

Skip if

• You require outdoor installation
• You cannot install 2x40A double-pole circuit breakers
• You need a flow rate higher than 4.9 GPM

Verdict: NOVIEEX 18kW 240V Electric Heater provides high flow and precise heat for small homes with adequate electrical infrastructure. It fits buyers who need multiple simultaneous fixtures and precise temperature control.

2 Best premium

Thermomate 18kW Electric Tankless Water Heater

Best for: Whole-house hot water with precise control

Fuel Type

Electric

Flow Rate

Up to 4.4GMP

Wattage

18kW

Installation Location

Indoor

Voltage

240V

Temperature Control

80°F to 140°F, ±1°F

View on Amazon: Thermomate 18kW Electric Tankless Water Heater

This ThermoMate unit delivers 18kW of power at 240V, heating water in three seconds with a flow rate of up to 4.4 GPM. It features self-modulating technology for 99.8% efficiency and a digital display allowing precise temperature adjustments in 1-degree increments from 80°F to 140°F. The compact, wall-mounted design saves space and fits tight areas. It requires two 40-amp breakers and 8AWG wiring for proper installation.

Pros

• 18kW heating capacity for whole-house use
• Up to 4.4 GPM flow rate
• Digital display with 1-degree adjustment
• 99.8% energy efficiency rating
• ETL certified safety protection

Cons

• Requires two double-pole 40-amp breakers
• Needs 8AWG wire gauge for installation
• Max temperature limited to 140°F

Good fit if

• You need a compact, wall-mounted unit
• You want precise digital temperature control
• You have the electrical capacity for 80A

Skip if

• You only have a single 40-amp breaker
• You cannot run 8AWG wiring
• You need temperatures above 140°F

Verdict: ThermoMate 18kW Electric Tankless Heater provides reliable whole-house hot water with efficient self-modulating technology. It suits homeowners with adequate electrical infrastructure who value precise digital temperature control and compact wall-mounting.

3 Best budget

ThermoMate 14kW Electric Tankless Water Heater

Best for: small homes and tight spaces

Fuel Type

Electric

Flow Rate

3.4 GPM

Wattage

14 kW

Installation Location

Indoor

Voltage

240 V

Temperature Control

86°F to 131°F

View on Amazon: ThermoMate 14kW Electric Tankless Water Heater

The ThermoMate 14kW unit delivers up to 3.4 GPM of hot water at 240 volts. It features a cast aluminum heating element and self-modulating temperature control between 86°F and 131°F. This compact, wall-mounted design weighs only 13 pounds. It suits small homes or apartments where space is limited. You get endless hot water for one or two fixtures simultaneously.

Pros

• 14 kW power output for instant hot water
• 3.4 GPM flow rate for single or dual fixture use
• Compact dimensions of 15.9 x 11.2 x 3 inches
• ETL listed for North American safety standards
• 99% thermal efficiency with self-modulating chip

Cons

• 14 kW rating is lower than the 18 kW alternatives on this list
• Requires a dedicated 60 Amp circuit breaker
• Indoor installation only

Good fit if

• You need a smaller unit for a tight space
• You are heating water for one or two fixtures
• You want an ETL listed electric heater

Skip if

• You require the full 18 kW capacity for whole-house use
• You cannot install a 60 Amp double-pole breaker
• You need outdoor installation capability

Verdict: ThermoMate 14kW 240V Electric Heater offers a compact, safe solution for smaller households. It fits buyers who prioritize space savings and safety certification over maximum flow rate.

4 Best 4.3 gpm

Ranein 18kW 4.3 GPM Electric Water Heater

Best for: whole-house showers and sinks

Fuel Type

Electric

Flow Rate

4.3 GPM

Wattage

18 kW

Voltage

240 V

Temperature Control

86°F to 131°F, 1°F increments

Certification

CSA

View on Amazon: Ranein 18kW 4.3 GPM Electric Water Heater

The Ranein 18kW unit delivers up to 4.3 GPM at 240V, supporting two to three simultaneous outlets. Its 99% thermal efficiency reduces standby loss, while the 86°F to 131°F digital control allows precise 1°F adjustments. The compact 18.7-inch design saves space, and CSA certification ensures safety for whole-house use.

Pros

• High 4.3 GPM flow rate for multiple outlets
• 99% thermal efficiency reduces energy consumption
• Precise 1°F temperature increments via LED display
• CSA certified for safety and durability

Cons

• Requires two dedicated 40A double-pole breakers
• Heavier at 17.4 pounds than some competitors
• No smart app or remote control mentioned

Good fit if

• You need high flow for whole-house use
• You want precise temperature control
• You have space for wall mounting

Skip if

• You cannot install two 40A circuits
• You prefer a lighter, smaller unit
• You need smart home integration

Verdict: The Ranein 18kW Electric Tankless Heater suits households needing reliable, high-volume hot water with precise temperature management. It fits users who can handle its electrical requirements and value certified safety features.

5 Best wifi

WINTEMP 18 kW Tankless Water Heater with WiFi

Best for: Remote temperature control via WiFi

Fuel Type

Electric

Flow Rate

Up to 4.3 GPM

Wattage

18 kW

Voltage

240V

Certification

ETL

Dimensions

19.2 x 11.1 x 4 inches

View on Amazon: WINTEMP 18 kW Tankless Water Heater with WiFi

The WINTEMP WN18 is an 18kW electric tankless water heater rated for 240V. It delivers a maximum flow rate of 4.3 gallons per minute. The unit features ETL certification and self-modulating technology to adjust power based on water flow. You can control the temperature remotely via WiFi. Its compact dimensions allow for wall mounting in tight spaces. This model suits homes with mild climates.

Pros

• 18kW output at 240V
• 4.3 GPM maximum flow rate
• WiFi remote temperature control
• ETL certified safety
• Self-modulating energy efficiency

Cons

• Requires 2 x 40 Amp DP breakers
• Needs 2 x 8/2 AWG wiring
• Limited to 240V electrical systems

Good fit if

• You have a dedicated 240V circuit with 80 Amp capacity
• You want to adjust temperature from another room
• You need ETL certification for safety

Skip if

• You only have a 120V outlet
• Your electrical panel cannot support two 40 Amp breakers
• You live in a very cold climate with low incoming water temperature

Verdict: WINTEMP 18kW WiFi Electric Heater fits buyers who need precise remote control and have the necessary 240V electrical infrastructure. It offers steady flow for mild climates but demands specific wiring upgrades.

6 Also great

Orbek 18kW 240V Tankless Electric Water Heater

Best for: Whole-house hot water with 240V power

Fuel Type

Electric

Flow Rate

4.22 GPM

Wattage

18 kW

Voltage

240V

Certification

ETL

Dimensions

17 x 13 x 3.9 inches

View on Amazon: Orbek 18kW 240V Tankless Electric Water Heater

The Orbek M-18 is an 18kW electric tankless water heater designed for whole-house use. It operates on 240V power and delivers up to 4.3 GPM. The unit features a compact wall-mounted design measuring 17 x 13 x 3.9 inches. It includes ETL certification for safety and offers self-modulating power to save energy. This model suits homes needing continuous hot water for multiple points of use.

Pros

• 18kW heating element provides instant hot water
• Compact wall-mounted design saves space
• ETL certified for safety protection
• Self-modulating power reduces energy use

Cons

• Requires 2 x 40 Amp DP breakers
• Needs 2 x 8/2 AWG wiring with ground
• Maximum amperage of 75A limits installation flexibility

Good fit if

• You have the electrical capacity for 75A
• You need a compact wall-mounted unit
• You want ETL certified safety features

Skip if

• You cannot install 240V circuits
• You lack space for 17-inch height
• You need gas-powered heating

Verdict: Orbek 18kW Electric Tankless Heater fits homes with adequate 240V electrical infrastructure. It delivers reliable whole-house hot water for users who value compact, certified safety.

7 Also great

SIVUATEK 18 kW Electric Tankless Water Heater

Best for: Whole-house hot water with high electrical capacity

Fuel Type

Electric

Flow Rate

4.3 GPM

Wattage

18 kW

Voltage

240V

Certification

ETL

Use

Whole House

View on Amazon: SIVUATEK 18 kW Electric Tankless Water Heater

The SIVUATEK 18kW unit delivers up to 4.3 GPM of hot water at 240V. Its self-modulating technology adjusts power based on flow rate to maintain consistent temperatures. The compact 3 x 11 x 15 inch design fits tight spaces. It features ETL certification and separate water and electrical lines to reduce corrosion. This model suits users needing reliable, endless hot water for whole-house or point-of-use applications.

Pros

• 18kW heating power supports up to 4.3 GPM flow rate
• Self-modulating system adjusts power to real-time flow and temperature
• Compact 3-inch depth saves space in utility areas
• ETL certified for safety in residential and commercial settings

Cons

• Requires a dedicated 40A double pole circuit breaker
• Needs 8AWG wiring with grounding for installation
• No smart app or remote control connectivity listed

Good fit if

• You need a high-flow unit for whole-house hot water
• You have the electrical capacity for a 40A circuit
• You want a compact heater with separate water and electrical lines

Skip if

• You only have a 30A circuit available
• You require Wi-Fi connectivity for remote monitoring
• You are installing in a location without 240V power

Verdict: The SIVUATEK 18kW Electric Tankless Heater offers strong flow and safety features for homes with adequate electrical infrastructure. It fits users who prioritize consistent temperature and space-saving design over smart connectivity.

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Frequently asked questions