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The Thermomate 18kW Electric Tankless Water Heater delivers instant hot water with precise temperature control in a compact, wall-mounted design. It is ideal for users who need reliable performance and have the necessary electrical infrastructure. However, you might want to explore thermomate 18kw electric tankless water alternatives if you require a different flow rate, a smaller footprint, or specific smart features. Some buyers also prefer brands with different certifications or installation requirements.
This list features seven alternatives that overlap with the original’s core specifications. Each unit shares the 18kW power rating and 240V voltage, ensuring similar heating capacity for whole-house or point-of-use applications. We selected these models because they offer variations in physical dimensions, flow rates, and additional features like digital displays or WiFi connectivity. You can compare these specs to find the best fit for your home’s electrical capacity and spatial constraints. The options range from budget-friendly choices to premium models with advanced monitoring tools.
01 How alternatives compare to Thermomate
APUS 18kW 4.4 GPM Tankless Water Heater
The APUS 18kW unit matches the Thermomate’s heating capacity and voltage but offers a more compact footprint. It measures 11.4 by 13.7 inches, making it narrower than the Thermomate’s 13.1 by 17.1-inch design. This model includes an LED display for temperature monitoring, whereas the Thermomate relies on its own digital interface. The APUS weighs 15.2 pounds, providing a solid build for whole-house applications. You should choose this alternative if wall space is tight and you prefer a smaller profile without sacrificing the 18kW power output or precise heat control.
NOVIEEX 18 kW 4.9 GPM Tankless Water Heater
The NOVIEEX 18kW heater prioritizes higher flow rates compared to the Thermomate. It is rated for up to 4.9 GPM, exceeding the Thermomate’s 4.4 GPM limit. This extra capacity suits households with simultaneous hot water demands. The unit draws a maximum of 75 amps, which is slightly lower than the Thermomate’s 76-amp requirement, potentially easing electrical load considerations. Its silver finish and 11.1 by 15.9-inch dimensions offer a different aesthetic and fit. Select this model if your primary need is maximizing water flow while maintaining precise temperature adjustments for bathroom fixtures.
Orbek 18kW 240V Tankless Electric Water Heater
The Orbek M-18 stands out for its significantly smaller size. Measuring just 8 by 11 inches, it is much more compact than the Thermomate’s 13.1 by 17.1-inch body. This makes it ideal for tight installations where space is at a premium. While it shares the same 18kW power and 240V requirement, it may offer slightly lower flow speeds due to its compact form factor. It is certified for safety and designed for point-of-use or whole-house applications. Choose this alternative if you need a wall-mounted unit that fits into restricted areas without compromising on basic electric heating performance.
WINTEMP 18 kW Tankless Water Heater with WiFi
The WINTEMP 18kW with WiFi adds remote connectivity to the standard electric tankless experience. Unlike the Thermomate, which requires manual adjustment, this model allows you to control settings via a mobile app. It maintains the same 18kW heating capacity and 240V operation. Its dimensions are 11.1 by 4 inches, offering a unique low-profile design that differs from the Thermomate’s taller shape. This feature suits users who want convenience and remote monitoring capabilities. Opt for this version if you value smart home integration and the ability to adjust water temperature from anywhere.
SIVUATEK 18kW Electric Tankless Water Heater
The SIVUATEK 18kW heater focuses on efficiency and moderate simultaneous demand. It shares the 18kW power rating and 240V requirement with the Thermomate. Its dimensions of 12.2 by 17.3 inches are similar but slightly wider. This model is designed for households that prioritize precise temperature control and high efficiency over maximum flow capacity. It fits well in homes where stable hot water delivery is more critical than peak GPM numbers. Choose this alternative if you need a reliable whole-house solution that balances power consumption with consistent heating performance for daily use.
WINTEMP 18kW Electric Tankless Water Heater
The WINTEMP 18kW without WiFi offers a compact, LED-displayed option for smaller households. It measures 9.7 by 14 inches, making it narrower than the Thermomate. This unit is designed for homes with 240V electrical capacity and specific flow needs for two to three fixtures. It includes an LED display for easy temperature reading, similar to other modern units. The 12-pound weight makes it lighter than the Thermomate. Select this model if you prefer a straightforward, certified heater with a smaller footprint and clear digital feedback, without the added complexity of smart connectivity features.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | Thermomate 18kW Electric Tankless Water Heater Best overall | precise temperature control and compact spaces | |
| 2 | APUS 18kW 4.4 GPM Tankless Water Heater Also great | Whole-house heating with precise temp control | |
| 3 | NOVIEEX 18 kW 4.9 GPM Tankless Water Heater Best premium | high flow rate needs | |
| 4 | Orbek 18kW 240V Tankless Electric Water Heater Best budget | compact wall-mounted whole-house heating | |
| 5 | WINTEMP 18 kW Tankless Water Heater with WiFi Also great | WiFi-enabled whole house hot water | |
| 6 | SIVUATEK 18kW Electric Tankless Water Heater Also great | moderate simultaneous hot water demand | |
| 7 | WINTEMP 18kW Electric Tankless Water Heater Also great | Small households with 240V electrical capacity |
Thermomate 18kW Electric Tankless Water Heater
Best for: precise temperature control and compact spaces
- Fuel Type
- Electric
- Max Flow Rate
- Up to 4.4GMP
- Heating Capacity
- 18kW
- Installation Location
- Indoor
- Voltage
- 240 Volt
- Temperature Range
- 80°F to 140°F
The Thermomate ET180 is an 18kW electric tankless water heater designed for indoor use. It delivers up to 4.4 GPM of hot water in 3 seconds at 240V. The unit features a digital display with 1°F adjustments from 80°F to 140°F. Its compact wall-mount design saves space. This model suits households needing reliable on-demand heating with precise temperature control.
- 18kW heating capacity for consistent hot water
- Up to 4.4 GPM flow rate
- Digital display with 1°F increment adjustments
- ETL certified for safety
- Compact wall-mount design
- Requires two 40-amp double-pole breakers
- Needs 8AWG wire gauge
- Max flow rate is lower than some competitors
- You need a compact unit for tight spaces
- You want precise temperature control
- You have the required electrical setup
- You cannot install 240V wiring
- You lack space for a 17.1-inch height unit
- You need more than 4.4 GPM flow
Verdict: Thermomate ET180 18kW Electric Tankless Heater fits users who prioritize precise temperature control and compact installation. It is ideal for those with the necessary electrical infrastructure who need reliable, instant hot water.
APUS 18kW 4.4 GPM Tankless Water Heater
Best for: Whole-house heating with precise temp control
- Fuel Type
- Electric
- Max Flow Rate
- Up to 4.4 GPM
- Heating Capacity
- 18kW
- Installation Location
- Indoor
- Voltage
- 240V
- Fixture Capacity
- 2–3 Points
This APUS unit delivers up to 4.4 GPM at 240V, supporting two to three simultaneous fixtures. Its slim 13.7 by 11.42 by 3.54 inch profile saves wall space while providing precise temperature control from 86 to 131°F. You get 99.8% thermal efficiency through self-modulating technology that adjusts power based on flow. The LED display allows 1°F increments and stores settings after power outages. It is built for indoor whole-house use.
- Delivers up to 4.4 GPM flow rate
- Slim dimensions of 13.7 x 11.42 x 3.54 inches
- 99.8% thermal efficiency with self-modulating power
- Precise temperature control from 86 to 131°F
- Built-in memory for preferred settings
- Heavier at 15.2 pounds than lighter competitors
- Requires 2 x 40A breakers and 8 AWG wire
- Limited to indoor installation only
- You need a high flow rate for multiple fixtures
- You want precise temperature adjustments in 1°F steps
- You have the electrical capacity for 40A breakers
- You require outdoor installation capabilities
- You cannot install 240V dedicated circuits
- You prefer a lighter unit under 15 pounds
Verdict: APUS 18kW Electric Tankless Water Heater suits homes needing robust flow and precise heat control. It fits buyers who can handle the weight and electrical requirements for reliable whole-house heating.
NOVIEEX 18 kW 4.9 GPM Tankless Water Heater
Best for: high flow rate needs
- Fuel Type
- Electric
- Max Flow Rate
- 4.9 GPM
- Heating Capacity
- 18kW
- Installation Location
- Indoor
- Voltage
- 240V
- Fixture Capacity
- 2-3 Points
The NOVIEEX 18kW electric tankless water heater delivers up to 4.9 GPM at 240V. It fits small to medium homes with 2-3 simultaneous fixtures. The unit measures 11.1 by 15.9 inches and mounts indoors. You get precise temperature control from 77°F to 140°F. It offers 99.8% thermal efficiency and an 8-layer safety system. This model suits households needing high flow rates without bulky storage tanks.
- High flow rate of up to 4.9 GPM
- Adjustable temperature range from 77°F to 140°F
- 99.8% thermal efficiency for energy savings
- 8-layer safety system with self-diagnosis
- Requires two 40A double-pole circuit breakers
- Needs two sets of 8 AWG wires
- Indoor installation only
- You need up to 4.9 GPM for multiple fixtures
- You have the electrical capacity for 75A total draw
- You want precise 1°F temperature adjustments
- You require outdoor installation
- You cannot install two 40A breakers
- You need WiFi connectivity
Verdict: NOVIEEX 18kW Electric Tankless Water Heater suits homes needing high flow rates and precise temperature control. It fits buyers with the necessary electrical infrastructure for its 75A draw.
Orbek 18kW 240V Tankless Electric Water Heater
Best for: compact wall-mounted whole-house heating
- Fuel Type
- Electric
- Max Flow Rate
- 4.22 GPM
- Heating Capacity
- 18 kW
- Voltage
- 240 V
- Fixture Capacity
- 2-3 Point of Use
- Installation Type
- Whole House
The Orbek M-18 is an 18kW electric tankless water heater designed for whole-house use. It delivers up to 4.22 GPM at 240V, providing instant hot water within three seconds. The compact unit measures 11 inches in height and mounts directly to the wall. It includes ETL certification and multiple safety protections like overheat and dry-fire prevention. This model suits homes needing reliable, on-demand heating without a storage tank.
- 18kW heating capacity for strong hot water output
- Max flow rate of 4.22 GPM supports multiple fixtures
- Compact 11-inch height saves wall space
- ETL certified for safety compliance
- Instant hot water in 3 seconds
- Max flow rate of 4.22 GPM is lower than the 4.4 GPM offered by the APUS model
- Requires 2 x 40 Amp DP breakers and specific 8/2 AWG wiring
- You need a compact unit that mounts easily on a wall
- You want ETL certification for peace of mind
- You are upgrading from a tank system to save space
- You require a flow rate higher than 4.22 GPM
- You cannot install two 40 Amp double-pole breakers
- You need WiFi connectivity for remote control
Verdict: Orbek M-18 18kW Electric Tankless is a solid choice for households prioritizing compact size and certified safety over maximum flow speed. It fits well in homes where electrical capacity is limited to 80 Amps total for the unit.
WINTEMP 18 kW Tankless Water Heater with WiFi
Best for: WiFi-enabled whole house hot water
- Fuel Type
- Electric
- Max Flow Rate
- 4.3 GPM
- Heating Capacity
- 18kW
- Voltage
- 240V
- Installation Type
- Whole House
- Features
- Tankless
The WINTEMP WN18 is an 18kW electric tankless water heater rated for 240V. It delivers up to 4.3 GPM of hot water. The unit measures 19.1 inches tall and weighs 12 pounds. It includes WiFi control for remote temperature adjustments. ETL certification ensures safety standards are met. This model suits homes with mild to moderate climate conditions.
- 18kW heating capacity for consistent hot water
- Up to 4.3 GPM flow rate
- WiFi control for remote temperature adjustment
- ETL certified for safety compliance
- 4.3 GPM flow rate is slightly lower than the 4.4 GPM offered by the APUS alternative
- Requires 2 x 40 Amp DP breakers and 2 x 8/2 AWG wiring for installation
- You want remote temperature control via WiFi
- You have a 240V electrical system with adequate breaker capacity
- You need ETL certification for safety assurance
- You require a flow rate higher than 4.3 GPM
- You cannot install dual 40 Amp breakers
- You need a unit smaller than 19.1 inches in height
Verdict: WINTEMP 18kW Electric Tankless Water Heater provides reliable hot water with WiFi convenience for homes with proper electrical infrastructure. It is a solid choice for users prioritizing remote control and certified safety over maximum flow speed.
SIVUATEK 18kW Electric Tankless Water Heater
Best for: moderate simultaneous hot water demand
- Fuel Type
- Electric
- Heating Capacity
- 18kW
- Voltage
- 240V
- Fixture Capacity
- 3–4 simultaneous usage points
- Temperature Range
- 86°F to 131°F
- Installation Type
- Whole House
This SIVUATEK unit delivers 18kW of heating power at 240V for whole-house use. It supports 3–4 simultaneous usage points with 99.8% thermal efficiency. The LED display allows precise temperature settings from 86°F to 131°F in 1°F increments. It features water-electricity separation technology for safety. This model suits homes needing steady hot water for multiple fixtures.
- 18kW heating capacity for high flow
- 99.8% thermal efficiency reduces energy loss
- Precise 1°F temperature adjustment increments
- LED display shows current settings clearly
- Water-electricity separation enhances safety
- Supports only 3–4 simultaneous usage points
- Dimensions are 17.3 inches in height
- Requires two 40-amp circuit breakers
- You need hot water for 3–4 fixtures
- You want precise temperature control
- You value high thermal efficiency
- You require more than 4 simultaneous outlets
- You cannot install two 40-amp breakers
- You prefer a smaller unit height
Verdict: SIVUATEK 18kW Electric Tankless Water Heater provides reliable whole-house hot water for households with moderate simultaneous demand. It fits homes that prioritize precise temperature control and high efficiency over maximum flow capacity.
WINTEMP 18kW Electric Tankless Water Heater
Best for: Small households with 240V electrical capacity
- Fuel Type
- Electric
- Max Flow Rate
- 4.3 GPM
- Heating Capacity
- 18kW
- Voltage
- 240V
- Fixture Capacity
- 2-3 points of use
- Features
- Tankless, LED Display
The WINTEMP WN18 is an 18kW electric tankless water heater rated for 240V. It delivers up to 4.3 GPM of hot water, suitable for two to three fixtures. The unit features an LED display and wall-mounted design. It includes safety protections like overheat and dry-fire prevention. This model is ETL certified for residential use.
- 18kW heating capacity for on-demand hot water
- Maximum flow rate of 4.3 GPM
- ETL certified for safety compliance
- LED display for real-time monitoring
- Wall-mounted design saves floor space
- Requires two 40 Amp double-pole breakers
- Needs 8/2 AWG wiring with ground
- Heavier at 12 pounds than some compact units
- You need hot water for two to three fixtures
- You have a 240V electrical panel with space for two breakers
- You want an ETL certified unit for safety
- You only have a single 40 Amp breaker available
- You need a flow rate higher than 4.3 GPM
- You prefer a unit without an LED display
Verdict: WINTEMP 18kW Electric Tankless Heater provides reliable hot water for small households with adequate electrical infrastructure. It fits buyers who prioritize certified safety and specific flow requirements for two to three fixtures.
02 Specifications side by side
| Spec | Thermomate 18kW Electric Tankless Water Heater | APUS 18kW 4.4 GPM Tankless Water Heater | NOVIEEX 18 kW 4.9 GPM Tankless Water Heater | Orbek 18kW 240V Tankless Electric Water Heater | WINTEMP 18 kW Tankless Water Heater with WiFi | SIVUATEK 18kW Electric Tankless Water Heater | WINTEMP 18kW Electric Tankless Water Heater |
|---|---|---|---|---|---|---|---|
| Fuel Type | Electric | Electric | Electric | Electric | Electric | Electric | Electric |
| Max Flow Rate | Up to 4.4GMP | Up to 4.4 GPM | 4.9 GPM | 4.22 GPM | 4.3 GPM | – | 4.3 GPM |
| Heating Capacity | 18kW | 18kW | 18kW | 18 kW | 18kW | 18kW | 18kW |
| Installation Location | Indoor | Indoor | Indoor | – | – | – | – |
| Voltage | 240 Volt | 240V | 240V | 240 V | 240V | 240V | 240V |
| Fixture Capacity | – | 2–3 Points | 2-3 Points | 2-3 Point of Use | – | 3–4 simultaneous usage points | 2-3 points of use |
| Temperature Range | 80°F to 140°F | 86–131°F | 77°F to 140°F | – | – | 86°F to 131°F | – |
| Installation Type | – | – | – | Whole House | Whole House | Whole House | – |
| Features | Tankless | Tankless, LED Display | Tankless | Tankless | Tankless | Tankless | Tankless, LED Display |
| Application | Shower | – | Bathroom | Point of Use | – | – | – |
| Form Factor | – | – | – | Compact | – | – | – |
| Wattage | 18 kW | 18 kW | 18 kW | 18 kW | 18 kW | 18 kW | 18 kW |
| Intended Use | – | – | – | Home | – | – | – |
| Dimensions | 13.1 × 13.1 × 17.1 inches | 11.4 × 11.4 × 13.7 inches | 11.1 × 11.1 × 15.9 inches | 8 × 8 × 11 inches | 19.1 × 11.1 × 4 inches | 12.2 × 12.2 × 17.3 inches | 9.7 × 9.7 × 14 inches |
| Weight | – | 15.2 pounds | – | – | 12 pounds | – | 12 pounds |
| Size | 240V/18kW | – | – | M-18 | 18kW | – | WN-18 |
| Color | Gray | Gray | Silver | Snow | Gray | Gray | Gray |
| Model | ET180 | AP-ADSK180-H18 | DS-18 | HEU-ET018A5W-M0 | WN18 | TSB-180 | YQ-WN18K |
03 Frequently asked questions
Which alternative is best for whole-house heating?
The APUS 18kW model is designed for robust whole-house heating. It provides precise temperature control alongside a flow rate of 4.4 GPM. This unit measures 11.4 by 13.7 inches and includes an LED display. It suits homes needing reliable heat distribution without sacrificing water pressure.
What is the highest flow rate among these options?
The NOVIEEX 18 kW unit offers the highest flow rate at 4.9 GPM. It is ideal for bathrooms with high demand. This model requires a 75A electrical draw. Its silver finish and compact 11.1 by 15.9-inch size fit well in standard utility spaces.
Is there a compact option for small spaces?
The Orbek 18kW model is the most compact choice. It measures only 8 by 11 inches, making it suitable for tight installations. It is certified for point-of-use or whole-house applications. This unit prioritizes safety and compact design over maximum flow speed.
Which heater offers WiFi connectivity?
The WINTEMP 18kW heater with WiFi provides remote control capabilities. It allows you to monitor and adjust settings from your device. This model is designed for whole-house hot water. It fits homes with proper electrical infrastructure and users who value convenience and certified safety.
Can these units handle simultaneous hot water use?
The SIVUATEK 18kW model supports moderate simultaneous demand. It is built for households needing reliable whole-house hot water. It prioritizes precise temperature control and efficiency. This gray unit measures 12.2 by 17.3 inches and operates on standard 240V power for consistent performance.
Which option is best for small households?
The WINTEMP 18kW Electric Tankless Heater fits small households well. It supports two to three fixtures simultaneously. It requires adequate 240V electrical capacity. This gray unit measures 9.7 by 14 inches and includes an LED display for easy temperature monitoring and control.
Do any alternatives include an LED display?
Both the APUS and WINTEMP models include LED displays. The APUS unit features a 4.4 GPM flow rate and a compact footprint. One WINTEMP model offers WiFi control. The other WINTEMP option provides precise control for smaller households. These displays help you monitor water temperature accurately.
