Introduction
Hot water is one of the most relied-upon utilities in any home. From morning showers to dishwashing, laundry, and handwashing, consistent hot water plays a major role in daily comfort. Traditional tank water heaters have long been the standard, but they come with clear drawbacks: limited capacity, long recovery times, wasted energy, and bulky installation requirements. As households grow more energy-conscious and space becomes more valuable, tankless electric water heaters have become a preferred alternative.
The ThermoMate Tankless Water Heater Electric 27kW at 240 Volt is designed to meet the demands of modern households that require powerful, reliable, and efficient hot water delivery. With an impressive output of up to 6.4 GPM under optimal conditions, self-modulating technology, and precise digital temperature control, this model positions itself as a high-performance solution for residential indoor use, particularly for showers and multiple fixtures.
This in-depth review explores every aspect of the ThermoMate 27kW electric tankless water heater, including its performance, energy efficiency, installation requirements, safety systems, and suitability for different household needs.
Product Overview
The ThermoMate 27kW Tankless Electric Water Heater is a high-capacity, on-demand hot water system designed for indoor residential applications. Unlike storage tank heaters, this unit heats water instantly as it flows through the system, delivering hot water within seconds and continuing for as long as needed.
With a maximum power draw of 114 amps and a heating capacity of 27 kilowatts, this heater is built for homes with high hot water demand. It is capable of supporting showers, sinks, and other fixtures simultaneously, depending on inlet water temperature and flow requirements.
The compact, wall-mounted design allows it to fit into tight spaces while freeing up valuable floor area, making it suitable for utility rooms, basements, and mechanical closets.
Technical Specifications and Product Data
| Feature | Details |
|---|---|
| Product Name | ThermoMate Tankless Water Heater Electric 27kW |
| Power Rating | 27kW |
| Voltage | 208–240V Adjustable |
| Maximum Current Draw | 114 Amps |
| Required Breakers | 3 × Double-Pole 40 Amp |
| Wire Gauge | 3 × 8 AWG |
| Maximum Flow Rate | Up to 6.4 GPM |
| Flow Rate at 35°F Rise | 5.27 GPM |
| Temperature Range | 80°F – 140°F |
| Temperature Adjustment | 1°F Increments |
| Heating Efficiency | Up to 99.8% |
| Installation Type | Indoor, Wall-Mounted |
| Water Connection | 3/4″ NPT |
| Unit Dimensions | 17.12″ × 13.12″ × 3.12″ |
| Certification | ETL Certified |
| Safety Features | Overheating Protection, Dry-Fire Protection |
Instant Unlimited Hot Water Performance
The defining feature of the ThermoMate 27kW Electric Tankless Water Heater is its ability to provide instant, unlimited hot water. Unlike tank-based systems that must store and reheat water, this unit activates only when water flows through it.
Hot water is delivered in approximately three seconds, eliminating long wait times and ensuring continuous supply. At a 35°F temperature rise, the heater can provide a flow rate of approximately 5.27 GPM, which is sufficient for:
- A full-sized shower running continuously
- A shower and sink operating at the same time
- Multiple handwashing points without temperature drop
In warmer climates or with higher inlet water temperatures, the system can reach up to 6.4 GPM, making it capable of supporting even more simultaneous demand.
Self-Modulating Power and Energy Efficiency
Energy efficiency is a major advantage of tankless electric water heaters, and ThermoMate has incorporated advanced self-modulating technology into this model. The heater continuously monitors incoming water temperature and flow rate, adjusting power usage in real time to deliver consistent hot water without wasting energy.
Key benefits of this system include:
- Heating water only when it is needed
- Eliminating standby heat loss
- Reducing overall electricity consumption
With a reported efficiency of up to 99.8%, the ThermoMate 27kW tankless water heater can reduce water heating costs by up to 60% compared to traditional electric tank heaters, depending on household usage patterns.
Stable Water Temperature Control
One of the most common complaints with older water heating systems is inconsistent temperature, especially when multiple fixtures are in use. ThermoMate addresses this issue with automatic energy adjustment technology that maintains stable water temperature regardless of changes in flow.
The digital control panel allows users to set the desired water temperature in precise 1-degree increments between 80°F and 140°F. Once set, the system continuously adjusts power output to maintain that temperature, even when another faucet or appliance is turned on.
This level of precision is particularly beneficial for showers, where sudden temperature fluctuations can be uncomfortable or unsafe.
Advanced Heating Element Design
The ThermoMate 27kW Electric Tankless Water Heater features a heating element design where the elements are separated from the water tubes. This configuration significantly reduces the risk of scale buildup, corrosion, and mineral deposits on the heating elements.
Advantages of this design include:
- Improved long-term performance
- Reduced maintenance requirements
- Extended service life of internal components
This is especially important in areas with hard water, where mineral buildup can shorten the lifespan of conventional heating elements.
Installation Requirements and Electrical Considerations
Due to its high power output, the ThermoMate 27kW model requires careful planning before installation. This unit draws a maximum of 114 amps and requires substantial electrical infrastructure.
Important installation requirements include:
- Three dedicated double-pole 40-amp circuit breakers
- Three separate 8 AWG wiring runs
- Strongly recommended 200-amp household electrical service
These requirements ensure stable and safe operation under full load. While the heater is compact and wall-mounted, electrical upgrades may be necessary in some homes, especially older properties with limited service capacity.
Professional installation by a licensed electrician is highly recommended to ensure compliance with electrical codes and optimal performance.
Safety Features and Certifications
Safety is a critical consideration for any high-powered electrical appliance, and the ThermoMate Tankless Water Heater Electric 27kW includes multiple protective systems.
Key safety features include:
- Overheating protection to prevent excessive temperature buildup
- Automatic shut-off when no water flow is detected
- Leak prevention through high-quality internal workmanship
The unit is ETL certified, confirming that it meets recognized safety and performance standards for residential electrical appliances.
These protections work together to provide peace of mind during everyday use, even under high-demand conditions.
Space-Saving Design and Aesthetic Appeal
Despite its powerful performance, the ThermoMate 27kW unit maintains a slim and compact profile. Measuring just over 17 inches tall and slightly more than 3 inches deep, it can be mounted on almost any wall without dominating the space.
This space-saving design offers several benefits:
- Frees up floor space compared to tank heaters
- Allows installation in utility closets, basements, or laundry rooms
- Contributes to a clean and modern mechanical setup
For homeowners seeking a minimalist and efficient solution, this design is a significant advantage.
Ideal Use Cases and Household Suitability
The ThermoMate 27kW Electric Tankless Water Heater is best suited for households with moderate to high hot water demand and adequate electrical capacity.
It is ideal for:
- Homes with multiple bathrooms
- Families that use showers back-to-back
- Residences with consistent daily hot water usage
- Properties upgrading from large electric tank heaters
However, it may not be suitable for homes with limited electrical service or those unwilling to upgrade their electrical infrastructure.
Long-Term Value and Operating Costs
While the initial installation cost may be higher due to electrical requirements, the long-term savings can be substantial. By eliminating standby energy loss and operating at near-maximum efficiency, the ThermoMate 27kW model can significantly reduce monthly energy bills over time.
Additionally, reduced maintenance needs and extended component lifespan contribute to lower ownership costs throughout the life of the unit.
Advantages and Considerations
Advantages
- Instant, unlimited hot water
- High flow rate suitable for multiple fixtures
- Self-modulating energy-saving technology
- Precise digital temperature control
- Compact, wall-mounted design
Considerations
- High electrical demand
- May require electrical service upgrades
- Professional installation recommended
Final Verdict
The ThermoMate Tankless Water Heater Electric 27kW at 240 Volt is a powerful and efficient solution for homeowners seeking reliable, on-demand hot water without the limitations of traditional tank systems. With its high flow rate, advanced self-modulating technology, and precise temperature control, it delivers consistent performance for demanding residential applications.
For households with adequate electrical capacity and a desire to reduce energy waste while improving comfort, this ThermoMate model represents a strong long-term investment in modern water heating technology.