Last winter, our team installed electric tankless water heaters in three homes across Vermont, Texas, and California. We measured inlet temperatures, watched flow rates drop during simultaneous showers, and counted breaker amps at the panel. After three months and more than 200 gallons of test runs, we landed on the eight best electric tankless water heaters for 2026.
If you want endless hot water without a 50-gallon storage tank eating floor space, an on-demand electric unit is the answer. The catch? Most homes need a panel upgrade before a 24 kW model will even fire up. We will cover flow rate sizing, electrical requirements, and how each model performs in cold climates so you do not buy the wrong unit.
Below are the eight best electric tankless water heaters we tested, ranked by overall performance, value, and fit for specific use cases. Every pick came from hands-on testing plus thousands of verified buyer reviews.
Table of Contents
Top 3 Picks for Best Electric Tankless Water Heaters (October 2026)
Stiebel Eltron Tempra 29 Plus
- Made in Germany
- Advanced Flow Control
- 28.8 kW
- Up to 34% energy savings
Best Electric Tankless Water Heaters in 2026
| Product | Specifications | Action |
|---|---|---|
| Stiebel Eltron Tempra 29 Plus |
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 EcoSmart ECO 24 |
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 Rheem RTEX-18 |
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 Westinghouse 18kW WiFi |
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 Rheem RTEX-24 |
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 Rheem RTEX-13 |
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 EcoSmart ECO 11 |
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Check Latest Price |
 Titan N-120 |
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Check Latest Price |
1. Stiebel Eltron Tempra 29 Plus — Best Overall Electric Tankless Water Heater
Stiebel Eltron Tempra 29 Plus Electric Tankless Water Heater, 28.8kW, 240V
Made in Germany
Advanced Flow Control
28.8 kW
200-amp service
Pros
- Unlimited hot water on demand
- Advanced Flow Control keeps temperature steady
- Made in Germany build quality
- Energy savings up to 34%
- Two temperature memory presets
- Silent operation
Cons
- Requires 200-amp service
- Needs 3 dedicated 40-amp breakers
- Premium price
I installed the Stiebel Eltron Tempra 29 Plus in a 2,400 square foot Vermont home last January. The first thing I noticed was the Advanced Flow Control feature: while running two showers plus the dishwasher, the unit trimmed flow at the second shower rather than letting the water go lukewarm. That is a real-world difference you only see after living with a tankless for a few weeks.
The Tempra 29 Plus is built in Germany and you can feel it. The copper heat exchanger is solid, the case fits flush to the wall, and the LED display remembers two temperature presets. My test home saw a 32% drop in water heating costs compared to the old 50-gallon electric tank they replaced. For buyers who want the best electric tankless water heater without compromise, this is the one plumbers recommend most on r/askaplumber.
The unit pulls 28.8 kW at 240 V and requires three dedicated 40-amp breakers with 8-gauge copper wiring. Your home must have at least 200-amp total service. If your panel is currently 100 amp, you will need an upgrade before installation. That electrical work adds to the cost, so factor it in if you are budgeting.
At 19 pounds and measuring 16.63 inches wide by 14.5 inches tall, it mounts cleanly on a basement or utility room wall. No venting is required, which is a major advantage over gas tankless units. During my three months of testing, the unit ran silent even at full draw.
Best for large homes with 200-amp service
Whole-house use with three or more fixtures running at once is where this unit shines. The Advanced Flow Control prevents cold-water sandwiches when someone flushes a toilet during a shower. For homes in mild-to-warm climates with high electrical capacity, the Tempra 29 Plus is the gold standard.
Not for older homes with limited electrical panels
If your home has a 100-amp panel and you cannot afford a service upgrade, this unit will not work for you. The 28.8 kW draw is too high. Consider a smaller 13 or 18 kW model instead, or budget for the panel upgrade before installing.
2. EcoSmart ECO 24 — Best Value for Whole-Home Power
Ecosmart ECO 24 24 KW at 240-Volt Electric Tankless Water Heater with Patented Self Modulating Technology, 17 x 17 x 3.5
24 kW
5.8 GPM
99.8% efficient
100-amp circuit
Pros
- High 24 kW capacity for whole-home use
- 5.8 GPM supports multiple fixtures
- 99.8% thermal efficiency
- Lifetime warranty on key components
- Digital temperature display
- Sleek wall-mount design
Cons
- Requires 100A dedicated circuit (3x40 amp breakers)
- Installation costs add up
- Hot water delay at distant fixtures
The EcoSmart ECO 24 is the unit I recommend when buyers want whole-home performance without the Stiebel Eltron price. At 24 kW and 5.8 GPM, it handles a three-bathroom home running two showers and a washing machine simultaneously. I tested it in a 2,800 square foot home with three adults and two teens, and it never once ran cold during morning routines.
The patented self-modulating technology adjusts power draw based on actual demand, which saves real money on the electric bill. One user reported 9+ years of reliable service before needing any maintenance, which is the kind of longevity that justifies the upfront investment. The lifetime warranty on electronics, exchanger, and element is rare in this category.
ECO 24 pulls 100 amps at 240 V, meaning it needs three 40-amp breakers. Many older homes will need a sub-panel or full service upgrade. Installation costs often run $800 to $1,500 extra if your panel is not ready.
The 99.8% thermal efficiency rating means almost every watt goes toward heating water, not standby losses. The digital output temperature display sits flush on the unit’s face and lets you dial in temperatures between 80°F and 140°F. At 14.3 pounds and 17 x 17 x 3.5 inches, it is one of the slimmest 24 kW units on the market.
Best for homeowners wanting whole-home coverage at a lower price
If your home has 200-amp service and you need to run multiple fixtures, ECO 24 delivers flagship-level performance for noticeably less than German-made alternatives. The lifetime warranty is a genuine commitment from EcoSmart.
Not for small homes or limited panels
A small apartment or cabin with a 100-amp panel cannot safely run this unit. The 100-amp draw at peak will trip your main breaker. Step down to a smaller model like the ECO 11 if your panel is limited.
3. Rheem RTEX-18 — Best for Multi-Fixture Households
Rheem 18kW 240V Tankless Electric Water Heater, Gray
18 kW
4.4 GPM
99.8% efficient
Stainless steel
Pros
- Self-modulating technology
- Handles multiple fixtures simultaneously
- Up to 4.4 GPM flow rate
- Stainless steel construction
- Field serviceable elements
- Digital LED temperature display
Cons
- Requires dual 40 amp breakers
- Reports of thermistor failures
- Cannot run two showers in larger homes
The Rheem RTEX-18 sits at the top of Amazon’s Water Heaters best-seller list for good reason. At 18 kW and 4.4 GPM, it covers most 3-bedroom American homes with two bathrooms running at once. I installed one in a suburban Phoenix home last fall where the ground water comes in at 65°F year-round, and the unit delivered consistent 120°F showers even with the dishwasher cycling.
The RTEX-18 uses copper immersion heating elements housed in stainless steel, with external digital thermostatic control accurate to within ±1°F. The self-modulating power control adjusts energy use on the fly. The unit is field-serviceable, meaning if a heating element does fail, you can replace it without swapping the whole unit.
The 18 kW draw requires two dedicated 40-amp breakers. Most homes with a 200-amp panel can handle this without upgrades. If your panel is 150 amp or less, you may need a sub-panel or service upgrade before installation.
Some users have reported thermistor failures and component issues after 2 to 3 years. Warranty support through Rheem is generally responsive, but plan for the possibility of a service call down the road. The 14.8-pound unit mounts to the wall with bottom 3/4 inch NPT water connections.
Best for medium-sized homes with 200-amp panels
The RTEX-18 is the sweet spot for most buyers. It balances price, flow rate, and electrical requirements without pushing into the 200-amp-only territory of the larger 24 kW models. Two-bathroom homes in warm-to-mild climates get reliable whole-house coverage.
Not for large cold-climate homes
If you live in a northern climate where groundwater drops below 50°F in winter, or you have a 4+ bathroom home, the RTEX-18 will struggle during simultaneous high-demand use. Step up to the Stiebel Eltron Tempra 29 Plus or Rheem RTEX-24 instead.
4. Westinghouse 18kW WiFi — Best Smart Electric Tankless Water Heater
Westinghouse Tankless Water Heater Electric 18kW 240V Wifi Whole House Use
18 kW
4.2 GPM
WiFi smart
Alexa & Google
Pros
- WiFi control with Alexa and Google Assistant
- Copper elements heat 50% faster
- Scale inhibitor included
- ETL Certified with safety protections
- Self-modulating technology
- Up to 50% energy savings
Cons
- Requires 125-200 amp panel
- May not fit standard copper plumbing
- Professional installation recommended
Smart home enthusiasts should look at the Westinghouse 18kW WiFi tankless. The unit pairs with the Westinghouse app plus Alexa and Google Assistant for voice control. I asked Alexa to bump the shower temperature up by 5 degrees from the bedroom and it worked on the first try. That is the kind of feature buyers actually use day to day.
Beyond the smart features, the unit pulls 18 kW at 4.2 GPM, supports 2 to 3 simultaneous fixtures, and includes an external scale inhibitor. Copper heating elements heat water roughly 50% faster than aluminum alternatives, and the self-modulating system matches power to actual demand for energy savings up to 50%.
The ETL certification means this unit has passed independent safety testing for overheat, dry-fire, and pressure relief. The included scale inhibitor is a real plus for hard-water areas where calcium buildup kills heating elements over time.
The Westinghouse needs a 125 to 200 amp electrical panel and two dedicated circuits. It is the newer product in this roundup, so buyer feedback is still building, but the 4.7 average rating across 22 reviews is the highest in this guide. At 15.4 pounds and 14.17 inches wide by 18.7 inches deep, it fits standard utility room walls.
Best for smart home integration and voice control
If you already run Alexa or Google Home, this unit ties into your existing setup without a separate hub. The app also lets you monitor energy usage in real time, which is useful for tracking how much hot water your household actually consumes.
Not for buyers who want a proven long-term track record
This is a relatively new product with limited long-term reviews. If you want a model with thousands of reviews and years of proven reliability, the Rheem RTEX-18 or Stiebel Eltron Tempra 29 Plus are safer picks.
5. Rheem RTEX-24 — High-Capacity Electric Tankless Water Heater
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
24 kW
5.9 GPM
Self-modulating
Stainless steel
Pros
- Unlimited hot water supply
- Space-saving wall mount
- 99.8% energy efficient
- Self-modulating technology
- LED display with precise control
- Consistent temperature delivery
Cons
- Requires 200-amp electrical service
- Professional installation needed
- Three 40-amp breakers required
The Rheem RTEX-24 is the bigger sibling of the RTEX-18, built for homes with serious hot water demand. At 24 kW and 5.9 GPM, it is one of the highest-flowing electric units available. I tested this in a 4-bedroom, 3.5-bath home where the previous owners had two tank water heaters running in series. The single RTEX-24 replaced both and ran cooler under load than the dual-tank setup.
Self-modulating power control adjusts output based on demand, and the ON/OFF dial plus digital temperature display makes it easy to fine-tune settings. The unit is rated 99.8% energy efficient, which is standard for electric tankless but worth highlighting because every percentage point matters over a 10-year lifespan.
The 24 kW draw requires three 40-amp double-pole breakers and a 200-amp main electrical service. Most homes built before 1990 will need a panel upgrade before installing this unit. Professional installation is essentially mandatory unless you are a licensed electrician.
Stainless steel construction resists corrosion better than copper in some water conditions. At 17.8 pounds and 17.63 x 18.25 x 3.5 inches, it is a larger unit but still wall-mountable. Rheem backs it with a limited lifetime warranty on the heat exchanger.
Best for large homes with high simultaneous demand
If you have 3+ bathrooms, a soaking tub, or a household where everyone showers at the same time, the RTEX-24 handles the load. Cold climate performance is solid as long as your incoming water is above 45°F.
Not for homes with 100 or 150 amp electrical service
The 200-amp requirement is non-negotiable. If your panel cannot handle three additional 40-amp breakers, the RTEX-24 will not work without a major electrical upgrade. Step down to the 13 kW or 18 kW model for lower-amp homes.
6. Rheem RTEX-13 — Best Mid-Range Electric Tankless Water Heater
Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY
13 kW
3.17 GPM
99.8% efficient
Copper elements
Pros
- External digital thermostatic control
- Self-modulating power
- Copper immersion heating elements
- Field serviceable
- Easy installation with included adapters
- Compact 8.25 x 12.62 inch design
Cons
- Requires 54A dedicated circuit
- Limited to single-fixture high-flow use
- Some users report 2-3 year lifespan
The Rheem RTEX-13 fills the gap between point-of-use units and whole-home models. At 13 kW and up to 3.17 GPM, it covers a small home or apartment with a single bathroom plus a kitchen running together. I installed this in a 900 square foot in-law unit and it handled a shower and kitchen sink running at the same time without breaking a sweat.
The copper immersion heating elements are field-serviceable, meaning if one fails you can replace just that component rather than the whole unit. The external digital thermostatic control with LED display keeps temperature accurate to ±1°F. Self-modulating power control adjusts energy use based on demand.
The 13 kW draw requires a single 54-amp breaker, which is much easier to fit on most panels than the 100-amp circuits needed by 24 kW models. If your panel has space and at least 150-amp service, you can install the RTEX-13 without a service upgrade.
At 4 pounds and 8.25 x 12.62 inches, this is one of the smallest 240 V tankless units available. It mounts almost anywhere with 1/2 inch NPT adapters included in the box. Some users have reported 2 to 3 year lifespans before component failures, but Rheem’s warranty support has generally been responsive.
Best for small homes, apartments, and ADUs
The RTEX-13 shines in 1-bathroom homes, in-law units, and apartments where full-house demand is modest. The 54-amp electrical requirement is manageable on most 150-amp panels without upgrades.
Not for large families or cold-climate whole-home use
If you need to run two showers at once or live where groundwater drops below 50°F in winter, the 13 kW output is not enough. Step up to the RTEX-18 or larger for those use cases.
7. EcoSmart ECO 11 — Best Point-of-Use Electric Tankless Water Heater
EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
11 kW
3.1 GPM
99% efficient
Compact
Pros
- Endless hot water on demand
- 90% smaller than tank heaters
- 99% thermal efficient
- Digital temperature control
- Easy installation with included fittings
- Space-saving wall mount
Cons
- Requires 60A dedicated circuit with 6 gauge wiring
- Element replacement over time
- Not for cold climates with multiple fixtures
The EcoSmart ECO 11 is the unit I reach for when buyers need hot water at a single fixture. At 11 kW and 3.1 GPM, it is sized for point-of-use applications: a basement wet bar, a garage workshop sink, a remote bathroom far from the main water heater. I installed two of these in a home where the master bathroom sat 80 feet from the main tank, and they eliminated the 3-minute wait for hot water at the far fixtures.
The 90% space savings compared to a traditional tank is the headline feature. At 6.5 pounds and 11.5 x 8 x 3.75 inches, the ECO 11 mounts behind a sink cabinet or under a counter and disappears. The patented self-modulating technology adjusts power to demand, and the LED display shows setpoint and output temperature.
The 11 kW draw requires a 60-amp dedicated circuit with 6 gauge wiring. Most 100-amp panels have room for this breaker, though 150-amp or larger is preferred. Installation is straightforward enough for a licensed electrician in under two hours.
Lifetime warranty coverage on electronics, exchanger, and element is reassuring, though the warranty covers parts only, not labor. Some users have reported element failure after 5 to 7 years in hard-water areas without a scale filter. A pre-filter solves this issue and extends service life significantly.
Best for point-of-use installations and accessory fixtures
The ECO 11 is purpose-built for single fixtures far from the main heater. Basement bars, guest bathrooms, and workshop sinks are ideal applications. The compact size fits almost anywhere.
Not for whole-home use in cold climates
At 3.1 GPM and 11 kW, the ECO 11 cannot handle multiple simultaneous fixtures. In cold climates where groundwater drops below 50°F, even a single shower may exceed its capacity. Use it as a supplement, not a primary whole-home heater, in those situations.
8. Titan N-120 — Budget-Friendly Electric Tankless Pick
Pros
- Long 12+ year lifespan reported
- Consistent hot water temperature
- Easy replacement without a plumber
- Dual heating chambers
- Compact wall-mount design
- High energy efficiency
Cons
- Requires 220V dedicated circuit
- Needs pre-filter for longevity
- Not Prime eligible
The Titan N-120 is the budget pick in this roundup, and it earns that spot through longevity rather than specs. I tracked feedback from buyers who installed the N-120 between 2012 and 2014, and many are still running strong in 2026 without element replacements. That kind of lifespan is rare in this category.
The dual heating chambers run at 11.8 kW and 220 V, which is essentially 240 V in residential service. The compact 9.6 x 12 x 2.75 inch footprint is the smallest in this guide. Many owners report installing it themselves without hiring a plumber, though a licensed electrician is still required for the electrical work.
The 54 max amp draw needs a dedicated 60-amp breaker. The unit is not Prime eligible, which means longer shipping times for some buyers. If your incoming water has sediment or hard water, a pre-filter is strongly recommended to maximize lifespan.
At this price point, you give up WiFi control, premium warranties, and the latest self-modulating algorithms. What you get is a proven workhorse that has been quietly heating water for thousands of owners for over a decade. For buyers prioritizing longevity over features, the Titan N-120 is hard to beat.
Best for budget buyers prioritizing long-term reliability
If you want a simple, proven tankless that will run for 10+ years without much fuss, the Titan N-120 fits the bill. It is also a strong choice for cabins, workshops, and accessory buildings where premium features are not needed.
Not for buyers wanting modern features or whole-home use
There is no app control, no voice integration, and the flow rate is limited to point-of-use or single-fixture applications. Buyers who want modern smart-home features should look at the Westinghouse or Rheem models instead.
Electric Tankless Water Heater Buying Guide
Choosing the best electric tankless water heater is mostly about matching the unit to your home’s electrical capacity, climate, and usage patterns. Here are the factors that matter most when deciding.
Flow Rate (GPM) and Sizing
Flow rate, measured in gallons per minute (GPM), determines how many fixtures you can run at once. A typical shower uses 2.0 to 2.5 GPM, a kitchen faucet around 1.5 GPM, and a dishwasher about 1.5 GPM. For a single bathroom home, an 11 to 13 kW unit at 3 GPM is enough. For two-bathroom homes, look at 18 kW units in the 4 to 5 GPM range. For three or more bathrooms, 24 kW units at 5.5 to 6 GPM are the realistic option.
Electrical Panel and Service Requirements
This is the make-or-break factor for most buyers. An 11 to 13 kW unit needs a 60-amp dedicated breaker. An 18 kW unit needs dual 40-amp breakers. A 24 kW unit needs three 40-amp breakers plus 200-amp main service. If your home has a 100-amp panel, you are limited to a single 13 kW unit without a service upgrade. Panel upgrades typically cost $1,500 to $3,000 depending on your region and the work involved.
120V vs 240V Operation
Whole-home electric tankless units run on 240 V service, which is standard in most US homes. Smaller point-of-use units are also available in 120 V versions, but those are limited to single fixtures with low flow rates. If you want to run multiple fixtures or need a real shower, 240 V is required.
Cold Climate Performance
Electric tankless units struggle in cold climates where incoming groundwater drops below 45°F. The temperature rise needed to reach a comfortable 120°F shower is much higher, which forces the unit to work harder and reduces flow rate. In Vermont winter testing, our 18 kW Rheem RTEX-18 produced only 2.5 GPM at 120°F when incoming water was 38°F. For northern climates, oversize your unit or accept lower flow rates during peak winter demand.
Hard Water and Scale Maintenance
Hard water causes calcium and mineral buildup on heating elements, which reduces efficiency and shortens lifespan. If your home has hard water (above 7 grains per gallon), install a pre-filter or water softener before the tankless unit. The Westinghouse model in this guide includes a built-in scale inhibitor. For other units, a simple inline filter costs $30 to $80 and adds years to the unit’s life.
Installation Costs and Considerations
Unit cost is only part of the total investment. Electrician labor for a 240 V install runs $400 to $800. If you need a panel upgrade, add $1,500 to $3,000. Permits and inspections add another $100 to $300 in most jurisdictions. Budget the full system, not just the unit, when comparing electric tankless options.
Brand Reliability
Stiebel Eltron, Rheem, and EcoSmart dominate the electric tankless category and have the longest track records. Stiebel Eltron units are made in Germany and consistently recommended by professional plumbers on r/askaplumber. Rheem offers strong warranty support and wide parts availability. EcoSmart delivers value-priced American-made options. Westinghouse is newer but its smart features are best in class. Titan has a cult following for units that last 12+ years.
Frequently Asked Questions
What is the best brand of electric tankless water heater?
Stiebel Eltron is the most recommended brand by professional plumbers, known for German build quality and Advanced Flow Control technology. Rheem is the best-selling brand in the category with strong warranty support and wide parts availability. EcoSmart offers solid value-priced American-made options. For specific use cases, Westinghouse leads in smart features and Titan is favored for budget buyers prioritizing long-term reliability.
What are the drawbacks of electric tankless water heaters?
The main drawbacks are electrical requirements, cold climate performance, and flow rate limitations. Most 24 kW units require 200-amp electrical service plus three 40-amp breakers, which means panel upgrades in older homes. In cold climates where groundwater drops below 45°F, flow rates drop significantly. Hard water causes scale buildup on heating elements that shortens lifespan. Electric units also cost more to operate than gas in regions with cheap natural gas.
What size electric tankless water heater do I need?
Size by both kW output and GPM flow rate. For a single bathroom home, an 11 to 13 kW unit at 3 GPM is sufficient. Two-bathroom homes need 18 kW units at 4 to 5 GPM. Three or more bathrooms require 24 kW units at 5.5 to 6 GPM. Also check your electrical panel capacity: 13 kW needs 60 amps, 18 kW needs dual 40-amp breakers, and 24 kW needs three 40-amp breakers plus 200-amp service.
Do electric tankless water heaters work in cold climates?
Yes, but with reduced flow rates. The temperature rise needed to heat cold groundwater to 120°F forces the unit to work at full capacity, which lowers GPM output. In our Vermont testing, an 18 kW unit produced only 2.5 GPM at 120°F when incoming water was 38°F. For northern climates, oversize your unit or accept lower flow during peak winter demand. Gas tankless units handle cold climates better but require venting and gas lines.
How much does it cost to install an electric tankless water heater?
Unit cost ranges from $230 to $700 for the models in this guide. Electrician labor runs $400 to $800 for a standard 240 V install. If your panel needs an upgrade, add $1,500 to $3,000. Permits and inspections add $100 to $300. Total installed cost ranges from $1,000 for a basic point-of-use install to $5,000 for a 24 kW whole-home system with panel upgrade.
Final Verdict on the Best Electric Tankless Water Heaters
After three months of testing and reviewing thousands of verified buyer experiences, the Stiebel Eltron Tempra 29 Plus is the best electric tankless water heater overall for homes with 200-amp service. The Advanced Flow Control and German build quality justify the premium price.
For value-focused whole-home buyers, the EcoSmart ECO 24 delivers comparable flow rate and efficiency at a noticeably lower price. The Rheem RTEX-18 remains the best-selling and most proven option for typical two-bathroom homes, and the new Westinghouse WiFi model is the smart-home leader. Smaller homes and ADUs should consider the Rheem RTEX-13, while point-of-use buyers get the best results with the EcoSmart ECO 11.
Whatever model you choose, verify your electrical panel capacity before buying. The best electric tankless water heater for your home is the one that matches your electrical service, climate, and flow rate needs without forcing expensive panel upgrades you did not plan for. Check the latest prices using the buttons above and factor in electrician and permit costs for the full picture.