Thermomate Mini Tank Water Heater or Thermomate Electric Tankless Water Heater? Which Thermomate Model to Buy
As an Amazon Associate we earn from qualifying purchases. Links on this page are affiliate links.
When comparing the thermomate mini tank water heater vs electric tankless water heater, you are choosing between stored and on-demand heating. Both units are electric and designed for point-of-use applications. The primary difference lies in their capacity and power requirements. The mini tank holds 6.5 gallons of pre-heated water, while the tankless model heats water instantly as it flows. This affects installation needs and flow performance significantly.
Key differences
| Aspect | Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank | Thermomate 11kW Electric Tankless Water Heater |
|---|---|---|
| Capacity | 6.5 Gallons | On-demand (no tank) |
| Voltage | 120 V | 208~240 V |
| Wattage | 1.44 kW | 11 kW |
| Flow Rate | Not listed | 2.15 GPM at 35°F rise |
| Dimensions | 17.7 x 17.7 x 14.6 inches | 11.8 x 3.13 x 14.8 inches |
| Certification | UL Listed | ETL |
Which one should you choose?
Choose Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank if
- You have a standard 120V outlet available under the sink.
- You need a steady supply of hot water for a single faucet without flow rate concerns.
- You prefer a unit with a glass-lined tank for durability.
Choose Thermomate 11kW Electric Tankless Water Heater if
- You have the electrical capacity for a 60Amp breaker and 240V wiring.
- You want to save space with a compact, wall-mounted design.
- You need higher flow rates for a bathroom or small sink.
Verdict: Choose the mini tank if your electrical setup is limited to 120V and you need a simple plug-in solution. Select the tankless model if you have the necessary 240V infrastructure and require higher flow rates or a smaller footprint.
Mini Tank vs Tankless Comparison
Capacity and Storage
The Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank provides a stored reserve of hot water. You get 6.5 gallons of pre-heated water ready for immediate use. This buffer helps if you need more than one fixture running briefly. In contrast, the Thermomate 11kW Electric Tankless Water Heater has no storage tank. It heats water only as it flows through. You get endless hot water, but the flow rate is limited to 2.15 GPM at a 35°F rise. If you need a quick shower or fill a large basin, the mini tank’s stored volume offers a distinct advantage over the tankless unit’s continuous but limited flow.
Power Requirements
Installation power needs differ significantly between these two models. The Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank operates on standard 120V power. It draws 12 amps and plugs into a regular outlet. This makes it easy to install in most homes without electrical upgrades. The Thermomate 11kW Electric Tankless Water Heater requires a dedicated 208-240V circuit. It draws up to 46 amps and needs a 60-amp breaker setup with 12AWG wire. This high demand often requires a professional electrician to install the proper circuitry. For standard household outlets, the mini tank is the clear winner.
Physical Dimensions
Size matters when fitting these units into tight spaces. The Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank measures 17.7 inches in height, 17.7 inches in width, and 14.6 inches in depth. It is a boxy unit that sits under a sink or counter. The Thermomate 11kW Electric Tankless Water Heater is much slimmer. It measures 14.8 inches in length, 11.8 inches in width, and only 3.13 inches in height. Its flat profile allows it to mount flush against a wall. If you have a very narrow cabinet or want a low-profile installation, the tankless model offers a better fit.
Temperature Precision
Both units offer adjustable temperature settings, but they manage heat differently. The Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank uses a thermostat with three levels, ranging from 50°F to 149°F. You select a set point, and the tank maintains that temperature. The Thermomate 11kW Electric Tankless Water Heater uses self-modulating technology. It continuously detects water temperature and flow rate to stay within 1°F of your selected temperature. This precise control ensures the water does not fluctuate as it passes through. For users who want exact temperature stability without guessing, the tankless model provides superior control.
Efficiency and Standby Loss
Energy efficiency depends on how the units retain heat. The Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank has a thermal efficiency of up to 99%. However, it still experiences some standby loss because it keeps water hot in the tank even when not in use. The Thermomate 11kW Electric Tankless Water Heater also claims 99% efficiency. Because it has no tank, it eliminates standby heat loss entirely. It only uses energy when water is flowing. This on-demand operation is more efficient for low-use scenarios where you do not need hot water constantly available.
Which Thermomate Model Suits Your Needs
Users needing instant hot water at a sink
This tankless unit heats water on demand with a flow rate of 2.15 GPM at a 35°F rise. Its self-modulating technology adjusts energy use based on flow, ensuring stable temperature control within 1°F. The compact 11.8-inch width fits tight spaces without a storage tank, making it ideal for under-sink installations where space is limited.
Buyers wanting easy 120V plug-in installation
This mini-tank operates on standard 120V power with a 12-amp nominal current, allowing you to plug it into a regular outlet. It holds 6.5 gallons of stored hot water, providing a buffer for brief multi-fixture use. The glass-lined tank offers durability, and the unit includes a temperature range from 50°F to 149°F with a freeze protection mode.
Those prioritizing stored hot water reserve
With a 6.5-gallon capacity, this unit stores hot water for immediate access without waiting for heating elements to activate. It delivers fast recovery and maintains thermal efficiency up to 99%. The included temperature and pressure relief valve adds safety, while the adjustable thermostat lets you set specific temperature levels to suit your daily hot water requirements.
Users seeking high-efficiency on-demand heating
This electric tankless heater achieves 99% efficiency by only using energy when water flows. It features alloy metal housing and separated heating elements to reduce scale and corrosion. The unit draws up to 46 amps on 208-240V power, requiring a 60-amp breaker setup. It provides endless hot water with continuous temperature monitoring for consistent performance.
The products compared
Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank
Best for: single sink point-of-use hot water
- Fuel Type
- Electric
- Wattage
- 1.44 kW
- Capacity
- 6.5 Gallons
- Voltage
- 120V
- Temperature Control
- 50°F to 149°F
- Certification
- UL Listed
View on Amazon: Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank Affiliate link
This Thermomate mini tank provides instant hot water for point-of-use applications like under-sink sinks. It holds 6.5 gallons and connects to a standard 120V outlet. The unit features a glass-lined tank with 99% thermal efficiency. You can adjust the temperature from 50°F to 149°F. Its compact 17.7-inch width fits well in tight spaces. It is ideal for small households needing localized hot water.
Pros
- 6.5-gallon capacity for point-of-use hot water
- Plugs into standard 120V outlet
- Adjustable thermostat from 50°F to 149°F
- 99% thermal efficiency with fast recovery
- UL Listed for safety
Cons
- 1.44 kW heating element is low for high-demand use
- Limited to 120V electrical connection
- 1-year parts warranty is shorter than tank warranty
Good fit if
- You need hot water for a single sink
- You have a standard 120V outlet nearby
- You want to reduce standby heat loss
Skip if
- You need to supply multiple fixtures simultaneously
- You require a 240V high-power connection
- You need an on-demand tankless design
Verdict: Thermomate 6.5 Gallon Under Sink Water Heater suits small kitchens or bathrooms where a single faucet needs immediate hot water. It fits users who prioritize easy 120V installation over high-volume output.
Thermomate 11kW Electric Tankless Water Heater
Best for: Single sink or bathroom point-of-use
- Fuel Type
- Electric
- Flow Rate
- Up to 2.6GPM
- Wattage
- 11kW
- Voltage
- 208~240 Volt
- Temperature Control
- Within 1°F
- Certification
- ETL Certified
View on Amazon: Thermomate 11kW Electric Tankless Water Heater Affiliate link
This Thermomate unit delivers on-demand hot water with an 11kW heating element. It operates on 208-240V and provides a flow rate of 2.15 GPM at a 35°F temperature rise. The compact design measures 11.8 inches wide and mounts to your wall. You get precise temperature control within 1°F. It is ideal for point-of-use applications like a bathroom sink or office break room where space is limited.
Pros
- 11kW power for instant hot water
- Precise temperature control within 1°F
- Compact wall-mounted design saves floor space
- Alloy metal housing resists corrosion
Cons
- Requires a dedicated 60Amp breaker setup
- Limited to point-of-use or low-flow applications
- Higher electrical requirement than mini-tank models
Good fit if
- You need endless hot water for a single sink
- You have the electrical capacity for a 60Amp circuit
- You want to save floor space with a wall mount
Skip if
- You need to heat water for multiple fixtures simultaneously
- You cannot install a 208-240V electrical line
- You prefer the simplicity of a pre-heated tank system
Verdict: Thermomate 11kW Electric Tankless Heater fits users who need reliable hot water for a single point of use and have the necessary electrical infrastructure. It is not suitable for whole-house heating or high-flow demands.
Specifications side by side
| Spec | Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank | Thermomate 11kW Electric Tankless Water Heater |
|---|---|---|
| Fuel Type | Electric | Electric |
| Flow Rate | not stated | Up to 2.6GPM |
| Wattage | 1.44 kW | 11kW |
| Capacity | 6.5 Gallons | not stated |
| Voltage | 120V | 208~240 Volt |
| Temperature Control | 50°F to 149°F | Within 1°F |
| Certification | UL Listed | ETL Certified |
| Dimensions | 17.7"H x 17.7"W x 14.6"D | not stated |
| Use | Under Sink | not stated |
| Weight | 26.5 pounds | not stated |
| Size | 6.5 Gallon | 240V/11kW |
| Color | white,blue | Gray |
| Model | ES700 | ET110 |
Frequently asked questions
Can I install the Thermomate 6.5-Gallon mini tank on a standard outlet?
Yes, you can. This unit operates on 120V power, which matches standard household circuits. You do not need special wiring or a dedicated high-amperage breaker. It is designed for easy installation under sinks where standard electricity is available. This makes it a practical choice for quick upgrades in kitchens or bathrooms.
Does the Thermomate 11kW tankless heater work with 120V power?
No, it does not. This model requires a 240V electrical supply. You must ensure your home has the correct voltage infrastructure before installing it. It is not compatible with standard 120V outlets. Check your electrical panel or consult an electrician to verify you have the necessary 240V circuit for this unit.
How much space does the Thermomate 6.5-Gallon unit take up?
The unit measures 14.6 inches wide, 21.2 inches high, and 17.7 inches long. It weighs 26.5 pounds. These dimensions allow it to fit under most standard kitchen or bathroom sinks. The compact footprint ensures it does not dominate your cabinet space while providing a reliable reserve of hot water for daily use.
What are the dimensions of the Thermomate 11kW tankless heater?
The tankless model is 11.8 inches wide, 3.13 inches high, and 14.8 inches long. Its slim profile allows it to mount on a wall without taking up floor space. The low height makes it suitable for tight areas where a bulkier tank would not fit. It is designed for discreet installation in utility spaces.
Which Thermomate model is better for a single bathroom sink?
Both models work, but the 11kW tankless unit is often preferred for its on-demand heating. It provides hot water only when you turn the tap. The 6.5-gallon mini tank offers a stored reserve, which is helpful if you need continuous hot water without waiting for reheating. Choose based on your electrical setup and space constraints.
Is the Thermomate 11kW heater suitable for whole-house use?
No, it is not. This unit is designed for single point-of-use applications, such as one sink or bathroom. It lacks the capacity to heat water for multiple fixtures simultaneously throughout a house. For whole-home needs, you would require a higher-capacity system. This model is best for localized hot water demands.