Electric tankless water heaters are among the most popular water heating systems of recent years. They are easy to use, easy to install, come in many sizes, save space and energy and, most importantly, give you an unlimited supply of hot water.
Compared with a conventional tank, an electric tankless heater may look expensive, but over a long service life it can save you money and gives you far less trouble. Below we compare six models: four whole-house units from Stiebel Eltron and Rheem, a small residential model and a point-of-use sink heater. Always have the electrical requirements checked by an electrician before you buy, because electric tankless heaters draw a lot of power.
| Product | Our Rating | ||
|---|---|---|---|
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Best overall
Stiebel Eltron Tempra 24 Trend Electric Tankless Water Heater, 24kW, 240V |
VIEW ON AMAZON | |
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Best for large homes
Stiebel Eltron Tempra Plus 29 Tankless Water Heater, 29kW |
VIEW ON AMAZON | |
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Best for multiple fixtures
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater |
VIEW ON AMAZON | |
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Most popular
Rheem 18kW 240V Tankless Electric Water Heater |
VIEW ON AMAZON | |
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Best budget
Rheem RTEX-13 13kW 240V Residential Tankless Electric Water Heater |
VIEW ON AMAZON | |
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Best for a single sink
ThermoMate Tankless Small Water Heater, 120V 3500W On-Demand for Sinks (Hardwired) |
VIEW ON AMAZON |
Best Electric Tankless Water Heater Reviews in 2026
Best Whole-House Electric Tankless Water Heaters
1. Stiebel Eltron Tempra 24 Trend Electric Tankless Water Heater, 24kW, 240V
The Tempra 24 Trend is a compact whole-house electric tankless heater from Stiebel Eltron, a brand known for premium German-engineered heaters. It gives continuous on-demand hot water, needs no venting, runs quietly and uses an auto-modulation system and solid copper heating elements. A digital display shows the set temperature.
- 24kW, 240V whole-house electric tankless heater
- Continuous, on-demand hot water, no venting needed
- Auto-modulation to save energy
- Solid copper heating system, digital temperature display
- Premium brand with a strong reputation for reliability
- Compact, quiet and no venting required
- Auto-modulation saves energy when demand is low
- Good value among the Stiebel Eltron models
- Very good owner feedback
- Needs substantial electrical capacity and professional installation
- Costs more than the smaller Rheem models
Our Verdict: Our top pick: a trusted brand and good owner feedback, with a more modest price than the bigger Tempra.
2. Stiebel Eltron Tempra Plus 29 Tankless Water Heater, 29kW
The Tempra Plus 29 is the most powerful heater in this group and is designed to supply an entire large home without any venting. A digital control lets you set the temperature, and the system combines the efficiency of tankless heating with reliable build quality, with savings on the hot water portion of your electric bill.
- 29kW whole-house tankless heater
- No venting required
- Digital temperature control
- Sleek design that fits almost anywhere
- Highest output of the models here, suited to large homes
- Proven reliability from Stiebel Eltron
- No venting needed, so installation is flexible
- Digital temperature control
- Most expensive heater in the roundup
- Needs a very large electrical service and heavy-gauge wiring
Our Verdict: For large homes with plenty of electrical capacity and a high budget.
3. Rheem RTEX-24 24kW 240V Electric Tankless Water Heater
The Rheem RTEX-24 delivers up to 5.9 GPM, enough for multiple fixtures in a mid-size home. It has digital thermostatic controls in 1-degree increments and requires 240V power with three 40-amp double-pole breakers and a recommended 200-amp household panel.
- 24kW model provides up to 5.9 GPM
- Digital thermostatic control in 1-degree increments
- Designed for multiple fixtures
- Requires three 40-amp breakers and a 200-amp service panel
- Strong flow rate for several showers or taps
- Rheem is a widely trusted, easy-to-find brand
- Accurate digital temperature control
- Parts and service are easy to find
- High electrical requirements, so check your panel first
- Costs slightly more than the similar Stiebel Eltron Tempra 24
Our Verdict: A solid, widely supported heater for a mid-size home with a 200-amp service.
4. Rheem 18kW 240V Tankless Electric Water Heater
The Rheem 18kW heater provides up to 4.4 GPM with an external digital thermostatic control that is accurate to within a degree. It uses two durable copper immersion heating elements that are field-serviceable, self-modulates its power to meet demand and has bottom 3/4-inch NPT connections for simple installation.
- 18kW, up to 4.4 GPM flow rate
- External digital control with LED display
- Self-modulating power
- Two serviceable copper heating elements
- A sweet spot of price and capacity for many homes
- Self-modulating power avoids wasting electricity
- Heating elements are serviceable in the field
- A very large owner base
- May struggle with several showers at once in a cold climate
- Requires an electrician for installation
Our Verdict: A popular middle choice that suits a small to medium home or one main shower.
Best Small and Point-of-Use Electric Tankless Water Heaters
5. Rheem RTEX-13 13kW 240V Residential Tankless Electric Water Heater
The RTEX-13 is Rheem’s small residential model with a flow rate of up to 3.17 GPM. It has an adjustable digital thermostat accurate to one degree, copper immersion heating elements, self-modulating power and 1/2-inch connections, and it claims 99.8 percent energy efficiency. A water-saving 1.5 GPM shower head is part of the package.
- 13kW, up to 3.17 GPM
- Digital thermostat accurate to 1 degree
- Self-modulating power control, 99.8 percent efficient
- Includes a 1.5 GPM water-saver shower head
- The lowest price among the whole-home models
- Suitable for a single bathroom, apartment or cabin
- High efficiency and accurate temperature control
- Small and easy to place
- Good owner feedback
- Limited capacity, so it supports only one shower at a time
- Output drops in very cold incoming water
Our Verdict: The best budget option for a single bathroom or a small home.
6. ThermoMate Tankless Small Water Heater, 120V 3500W On-Demand for Sinks (Hardwired)
The ThermoMate is a small point-of-use heater that supplies instant hot water to a sink. It draws 3500 watts at 120V and about 29 amps, flows at 0.4 to 0.66 GPM and has a temperature range of 86 to 131 degrees F. It must be hardwired, with no plug, and the cast aluminum heating element is separated from the water line to reduce scale.
- 3500W, 120V, point-of-use heater for sinks
- 0.4-0.66 GPM, 86-131 degrees F range
- Must be hardwired, no plug
- Compact 7.9 x 6.4 x 2.5 inch body
- Gives hot water in seconds at a distant sink
- Very compact, fits under a sink
- Element is separated from the water to resist scale
- Low cost compared with whole-house units
- Only for a sink, not a shower
- Must be hardwired on a dedicated circuit
Our Verdict: The right choice only for a single sink, not for a shower.
What Do Electric Tankless Water Heaters Cost?
Electric tankless water heaters come in a great range of prices. Compact point-of-use units can cost around $100 to $150 and are enough for a single sink. Units around $200 to $300 can supply a single bathroom or one shower. Models around $300 to $600 offer 3 to 6 GPM and work for a small to medium house, and often come with longer heat exchanger warranties. At $700 and above you get the premium, high-capacity units, which are designed to supply the whole home at once.
How to Choose an Electric Tankless Water Heater
- Size it correctly. Add up the flow rate (GPM) of the fixtures you will run at the same time, such as a shower, a kitchen tap and a washer, and check the temperature rise the heater can deliver in your coldest months.
- Check your electrical service. Large heaters need several 40-amp or 50-amp breakers and often a 200-amp service panel. Smaller models need less, and the very small point-of-use units may need a dedicated circuit.
- Look at controls. A digital thermostat with accurate temperature control is more convenient and avoids scalding.
- Warranty and serviceability. Look for a long heat exchanger warranty and field-serviceable parts.
- Installation. Hire a licensed electrician and plumber. Always read the manual and follow the safety instructions, and keep children away from the unit.
For other options see our gas tankless water heater reviews, portable tankless water heater reviews and the guide gas vs electric tankless water heaters. To understand how they operate, see how tankless water heaters work.
Before you buy
Write down your hot water needs first, compare the specifications and check that your home’s electrical system can support the model. If in doubt, ask an electrician.
