Stiebel Eltron vs Thermomate: Tankless Water Heaters Compared by Specs
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The stiebel eltron vs thermomate tankless water heater comparison highlights two distinct electric heating solutions. Both units deliver hot water without gas lines. The Stiebel Eltron Tempra 29 Plus is a high-power tankless model designed for whole-home use. The Thermomate unit is a small under-sink mini-tank. One provides continuous flow for multiple fixtures. The other offers instant heat for a single point of use. Your choice depends on your power supply and hot water needs.
Key differences
| Aspect | Stiebel Eltron Tempra 29 Plus 28.8kW Tankless | Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank |
|---|---|---|
| Type | Tankless | Mini-tank (6.5 Gallons) |
| Voltage | 240 V | 120 V |
| Wattage | 28,800 W | 1.44 kW |
| Installation | Hard-wired | Plug-in |
| Use | Whole home or multiple fixtures | Point of use (under sink) |
Which one should you choose?
Choose Stiebel Eltron Tempra 29 Plus 28.8kW Tankless if
- You need hot water for multiple fixtures simultaneously.
- You have a 200-amp electrical service and can install hard-wired 240V circuits.
- You want unlimited hot water without a storage tank.
Choose Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank if
- You only need hot water for a single sink.
- You want a plug-in unit that fits under a counter.
- You prefer a 120V outlet installation without major electrical upgrades.
Verdict: Choose the Stiebel Eltron if you require high-capacity, continuous hot water for showers or multiple taps. Select the Thermomate if you need a compact, easy-to-install solution for a single sink or point-of-use application.
Stiebel Eltron vs Thermomate Spec Showdown
Power and Output
The Stiebel Eltron Tempra 29 Plus delivers 28,800 watts at 240 volts, designed for high-volume hot water needs. This power level supports whole-home applications, such as multiple simultaneous showers. In contrast, the Thermomate Mini Tank operates at just 1.44 kW on a standard 120-volt circuit. Its low wattage limits it to point-of-use tasks like a single kitchen sink. If you need to heat water for an entire household, the Stiebel Eltron’s superior wattage is essential. The Thermomate simply cannot match this output capacity.
Water Capacity
The Stiebel Eltron Tempra 29 Plus is a tankless unit, meaning it heats water on demand without storing it. It provides a continuous supply as long as the electrical service holds. The Thermomate features a 6.5-gallon glass-lined tank. This stored water allows for immediate hot water availability at the fixture, even if the heating element is cycling. However, the tank will eventually run out, requiring recovery time. For endless hot water, the tankless Stiebel Eltron wins. For instant availability at a single tap, the Thermomate’s tank offers a buffer.
Electrical Requirements
Installation complexity differs significantly between these two units. The Stiebel Eltron requires hard-wired 240-volt service with three dedicated 40-amp breakers and 8-gauge copper wiring. It also mandates a minimum 200-amp total home service. This is a major electrical upgrade for most homes. The Thermomate plugs into a standard 120-volt outlet with a 2-foot power cord and draws only 12 amps. You can install the Thermomate in almost any kitchen or bathroom without upgrading your electrical panel. The Thermomate is far easier to install for average homeowners.
Physical Footprint
Size matters for where you can place the unit. The Stiebel Eltron Tempra 29 Plus measures 14.5 x 16.6 x 4.63 inches and weighs 19 pounds. Its slim profile allows mounting on a wall in a utility closet or garage. The Thermomate is bulkier, measuring 17.7 x 17.7 x 14.6 inches and weighing 26.5 pounds. Its cubic shape makes it suitable for under-sink cabinets or floor mounting. If space is tight in a narrow utility area, the Stiebel Eltron’s thin design is advantageous. For under-sink storage, the Thermomate fits standard cabinet depths.
Temperature Control
Both units offer adjustable temperature settings, but the mechanisms differ. The Stiebel Eltron uses two temperature memory presets for quick adjustment. This allows you to switch between different hot water needs easily. The Thermomate features a thermostat with three settings, ranging from 50°F to 149°F. It also includes a freeze mode to protect the tank in cold environments. The Thermomate offers a wider temperature range and specific freeze protection, which is useful for unheated spaces. The Stiebel Eltron focuses on preset convenience rather than a wide adjustable range.
Certifications and Safety
Safety certifications ensure long-term reliability and compliance. The Thermomate is UL Listed and includes a temperature and pressure relief valve. It also comes with a 3-year limited warranty for the tank and a 1-year warranty for parts. The Stiebel Eltron data does not explicitly list UL certification or specific warranty terms in the provided specifications. While Stiebel Eltron is a reputable brand, the Thermomate provides explicit warranty details and safety certifications in its specs. For buyers prioritizing documented warranty coverage and listed safety marks, the Thermomate offers more transparent information.
Which unit fits your hot water needs
Whole-home high-flow requirements
You need continuous hot water for multiple fixtures. This Stiebel Eltron model delivers 28,800 watts at 240 volts. It supports whole-home use with dedicated 40 amp breakers. The 29 kW output handles simultaneous showers. You must have 200 amp total service. This unit provides unlimited hot water on demand for high-demand households.
Under-sink point-of-use installation
You want instant hot water at a single sink. This Thermomate unit holds 6.5 gallons for quick recovery. It plugs into a standard 120-volt outlet. The compact size fits under counters. You get adjustable temperature settings from 50°F to 149°F. It is UL listed and includes a pressure relief valve for safe, localized heating.
Simple plug-in convenience
You prefer easy installation without electrical upgrades. This mini tank connects to a standard 120-volt plug. It draws only 12 amps. No hardwiring or dedicated circuits are needed. The glass-lined tank retains heat efficiently. You get fast recovery times for small tasks. It is ideal for kitchens or bathrooms where whole-home power is not available.
Space-saving wall mount
You want a compact unit that saves floor space. This Stiebel Eltron model measures 14.5 by 16.6 inches. It mounts on the wall without venting. The sleek design fits in utility areas. You get two temperature memory presets for easy adjustment. It requires 8 gauge copper wiring. This option is best for those with adequate electrical capacity who want a clean look.
The products compared
Stiebel Eltron Tempra 29 Plus 28.8kW Tankless
Best for: high-demand households with 200-amp service
- Fuel Type
- Electric
- Wattage
- 28.8 kW
- Voltage
- 208 V, 240 V
- Dimensions
- 14.5 x 16.6 x 4.63 in
- Use
- Whole House
- Weight
- 19 pounds
View on Amazon: Stiebel Eltron Tempra 29 Plus 28.8kW Tankless Affiliate link
The Stiebel Eltron Tempra 29 Plus is a 28.8kW electric tankless water heater designed for continuous hot water. It operates on 240V with a maximum draw of 28,800 watts. The unit features two temperature memory presets for easy adjustment. Its compact dimensions of 14.5 x 16.6 x 4.63 inches save space. It requires hard-wiring with three dedicated 40-amp breakers and 8-gauge copper wiring.
Pros
- 28.8kW power output at 240V
- Two temperature memory presets
- Compact 14.5 x 16.6 x 4.63 inch design
- No venting required
Cons
- Requires three dedicated 40-amp breakers
- Needs 8-gauge copper wiring
- Minimum 200-amp residential service required
Good fit if
- You have a 200-amp electrical service
- You need high-flow hot water for multiple fixtures
- You want space-saving wall-mount installation
Skip if
- You only have a 100-amp electrical panel
- You cannot install three 40-amp breakers
- You prefer plug-in appliances over hard-wired units
Verdict: Stiebel Eltron Tempra 29 Plus 28.8kW delivers reliable high-capacity hot water for homes with robust electrical infrastructure. It suits households needing simultaneous hot water for showers and sinks, provided you can support the necessary wiring and breaker requirements.
Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank
Best for: single sink point-of-use installation
- 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 unit is a 6.5-gallon electric mini tank designed for point-of-use installation under sinks. It operates on 120V with 1.44 kW of power. The glass-lined tank offers 99% thermal efficiency and includes a UL Listed safety certification. You get an adjustable thermostat ranging from 50°F to 149°F. This compact heater suits small households needing instant hot water at a single fixture without waiting for main line recovery.
Pros
- 6.5-gallon capacity for point-of-use hot water
- 120V plug-in connection for easy installation
- Glass-lined tank with 99% thermal efficiency
- UL Listed for safety certification
- Adjustable thermostat from 50°F to 149°F
Cons
- 1.44 kW heating element is low for high-demand use
- 6.5-gallon tank is small for whole-house needs
- 3-year tank warranty is shorter than industry standards
Good fit if
- You need hot water for a single sink
- You want a 120V plug-in unit
- You require a compact under-sink heater
Skip if
- You need whole-house hot water
- You require high-flow continuous heating
- You need a larger storage capacity
Verdict: ThermoMate 6.5 Gal Mini Tank is a practical solution for single-sink applications where space is limited. It fits buyers who need instant hot water at one fixture without complex wiring.
Specifications side by side
| Spec | Stiebel Eltron Tempra 29 Plus 28.8kW Tankless | Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank |
|---|---|---|
| Fuel Type | Electric | Electric |
| Wattage | 28.8 kW | 1.44 kW |
| Capacity | not stated | 6.5 Gallons |
| Voltage | 208 V, 240 V | 120V |
| Temperature Control | not stated | 50°F to 149°F |
| Certification | not stated | UL Listed |
| Dimensions | 14.5 x 16.6 x 4.63 in | 17.7"H x 17.7"W x 14.6"D |
| Use | Whole House | Under Sink |
| Weight | 19 pounds | 26.5 pounds |
| Size | 29 (kW) | 6.5 Gallon |
| Color | White | white,blue |
| Model | 239223 | ES700 |
Frequently asked questions
Is Stiebel Eltron better than Thermomate for whole-home use?
Yes, if you need continuous hot water for multiple fixtures. The Stiebel Eltron Tempra 29 Plus delivers 28.8 kW of power at 240 volts. It is designed for high-demand households with robust electrical infrastructure. Thermomate offers a 6.5-gallon mini-tank instead, which is only suitable for single sink point-of-use installation.
What is the difference in electrical requirements between these brands?
The Stiebel Eltron unit requires a 240-volt connection and supports high wattage for whole-home heating. The Thermomate mini-tank operates on standard 120-volt power. This makes Thermomate easier to install in locations with limited electrical capacity, while Stiebel Eltron needs dedicated heavy-duty wiring and breakers.
Which tankless water heater is smaller in size?
The Thermomate 6.5-Gallon unit is physically larger in volume but smaller in footprint for under-sink use. It measures 14.6 inches wide and 21.2 inches tall. The Stiebel Eltron Tempra 29 Plus is a wall-mounted tankless unit measuring 16.6 inches wide and 14.5 inches tall. You must check your installation space carefully for both.
Can Thermomate replace a Stiebel Eltron unit for showers?
No, Thermomate is not designed for shower use. It is a 6.5-gallon under-sink mini-tank intended for single sink point-of-use applications. Stiebel Eltron provides high-capacity hot water suitable for simultaneous showers. You should only choose Thermomate if you need instant hot water at one fixture without complex wiring.
How much does the Stiebel Eltron Tempra 29 Plus weigh?
The Stiebel Eltron Tempra 29 Plus weighs 19 pounds. This weight applies to the 28.8 kW tankless model. In comparison, the Thermomate 6.5-Gallon unit weighs 26.5 pounds. Both units are relatively light for wall or counter mounting, but you should verify your mounting surface can support these specific weights.
Is Stiebel Eltron electric or gas powered?
Stiebel Eltron is electric powered. The Tempra 29 Plus runs on 240 volts and delivers 8 kW per phase for a total of 28.8 kW. It does not use gas lines. Thermomate is also electric, operating at 120 volts. Both brands provide electric heating solutions without requiring gas infrastructure.
What is the model number for the Stiebel Eltron unit?
The model number for the Stiebel Eltron Tempra 29 Plus is 239223. This corresponds to the 28.8 kW tankless water heater. The Thermomate unit uses the model designation ES for its 6.5-gallon under-sink mini-tank. You can use these numbers to verify compatibility with your existing plumbing and electrical systems.