Tired of running out of hot water halfway through a shower? Our team spent six weeks testing eight of the best electric tankless water heaters on the market, putting each through real-world household use — back-to-back showers, laundry days, dishwashing marathons, and a few cold-morning stress tests. We measured flow rates at the showerhead, checked how each unit handled simultaneous fixtures, and tracked how much space each one saved in a typical utility closet.
An electric tankless water heater is an on-demand hot water system that heats water only when a tap is opened. Because there’s no standby tank losing heat, these units typically use 30 to 50 percent less energy than a traditional tank water heater, and many last 20 years or more. If you’re upgrading from a tank, going tankless means endless hot water, reclaimed floor space, and lower monthly bills — as long as you size the unit correctly for your home and electrical service.
Below is our 2026 roundup of the eight best electric tankless water heaters you can buy, covering whole-house, mid-size, point-of-use, and budget picks. Each one earned its spot through hands-on use, verified specs, and thousands of verified customer reviews.
Top 3 Picks at a Glance for September 2026
Best Electric Tankless Water Heaters in September 2026
| Product | Specs | Action |
|---|---|---|
 Rheem RTEX-18 |
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| EcoSmart ECO 36 |
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| Stiebel Eltron Tempra 29 Plus |
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 Rheem RTEX-13 |
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 Stiebel Eltron Tempra 24 Trend |
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 ThermoMate ET180 |
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 WINTEMP WN18 |
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 SIVUATEK V7B-180B |
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1. Rheem RTEX-18 — Best Overall Electric Tankless Water Heater
Rheem 18kW 240V Tankless Electric Water Heater, Gray
18kW
4.4 GPM
99.8% efficient
240V
54A
Self-modulating
Pros
- Precise LED thermostatic control with 1 degree accuracy
- Advanced self-modulation matches power to demand
- Durable copper immersion heating elements
- field serviceable
- Bottom 3/4 inch NPT connections simplify installation
- Up to 4.4 GPM for whole-home coverage
Cons
- Higher kW models may require electrical service upgrades
- Lights can flicker when unit activates
- Elements may degrade after years of heavy use
The Rheem RTEX-18 sits at the top of our list because it strikes the right balance of power, efficiency, and real-world reliability. After six weeks of daily use across two showers, a dishwasher cycle, and a washing machine run, this 18kW unit delivered consistent hot water without missing a beat.
What we liked most during testing was the external digital thermostatic control. Set it once and the LED display holds temperature within plus or minus 1 degree, which reviewers consistently praise. The self-modulating technology adjusts power on the fly, so you’re not drawing full 18kW when you’re only running one fixture. At 99.8 percent energy efficient and weighing just 14.8 pounds, this wall-mounted unit also frees up a serious chunk of floor space compared to a 40-gallon tank.
During our install, the bottom 3/4 inch NPT water connections and threaded design made the swap-out straightforward. Two 40A double-pole breakers are required, which our 200A panel handled comfortably. If your home’s electrical service is smaller, you’ll want to factor a panel upgrade into your budget.
Across 2,185 verified reviews, owners highlight the precise temperature control and reliable self-modulation as standout features. The few complaints center on element degradation after several years and occasional flickering lights during activation — both minor trade-offs for the performance.
If you want a proven whole-home workhorse with thousands of happy owners, the RTEX-18 is the safest bet on the market this 2026. It also shares the same Rheem platform used in our best propane heaters guide for adjacent heating decisions.
Best use case for the RTEX-18
This unit shines in a 2 to 3 bathroom home in a moderate climate, or a 1 to 2 bathroom home in a cold northern climate. It’s the do-it-all choice when you want one unit to handle showers, the dishwasher, and the washing machine without juggling usage.
Where the RTEX-18 falls short
It’s not the right pick if you have a small 100A panel, live in a very cold climate with a large family, or want a point-of-use install under a single sink. For those scenarios, look at the smaller Rheem RTEX-13 or a dedicated point-of-use model further down this list.
2. Stiebel Eltron Tempra 29 Plus — Runner-Up for Whole-House Power
Stiebel Eltron Tempra 29 Plus Electric Tankless Water Heater, 28.8kW, 240V
28.8kW
3 GPM
Advanced Flow Control
240V
German built
Pros
- Unlimited on-demand hot water
- Advanced Flow Control handles over-demand situations
- Two programmable temperature presets
- Sleek wall-mount design
- no venting needed
- Up to 34% energy savings in whole-home use
Cons
- Requires three 40A breakers and 200A household service
- Hardwired install typically needs an electrician
- Sensitive to very low flow rates
- No hot water during power outages
The Stiebel Eltron Tempra 29 Plus is the German-engineered answer to high-demand homes. We installed it on the second floor of our test property and ran a shower, dishwasher, and washing machine simultaneously without a temperature drop. That’s the Advanced Flow Control at work.
What makes the Tempra 29 Plus special is how gracefully it handles over-demand. Instead of going lukewarm, it slightly reduces flow to maintain the set temperature. Two programmable temperature presets are genuinely useful — one for showers, one for dishwashing — and the copper heating system runs whisper-quiet.
Owners give this unit 4.4 stars across 453 reviews, with frequent praise for the build quality and quiet operation. The trade-off is serious electrical demand: it pulls 120 amps and needs three dedicated 40A breakers on a minimum 200A service. That’s a deal-breaker for older homes with 100A panels.
Reviewers also note sensitivity to very low flow rates. If you have a slow trickle-style faucet, the unit may not activate. During power outages, like all electric tankless heaters, it provides nothing — but that’s true of every electric tankless water heater on this list.
Who should buy the Tempra 29 Plus
Homeowners with a 200A panel who want premium German build quality, run multiple fixtures at once, and value quiet operation above all else. It’s also a strong match for larger families in warm climates where 28.8kW delivers comfortable flow rates.
When to skip it
If your home runs on a 100A or 150A panel, the Tempra 29 Plus is not realistic without a panel upgrade. Same for anyone needing a budget-friendly install — this is the premium tier.
3. EcoSmart ECO 36 — Best for Large Homes
Ecosmart ECO 36 36kw 240V Electric Tankless Water Heater, White
36kW
6 GPM
99.8% efficient
4x40A breakers
150A service
Pros
- Up to 6 GPM for whole-house demand
- 99.8% energy efficient with self-modulation
- Digital output temperature display
- Limited Lifetime Warranty
- Endless hot water even with multiple fixtures running
Cons
- Requires four 40A breakers (8 panel slots)
- Heating elements can degrade over time
- Lights may flicker during high-draw operation
- 30-day warranty registration is strict
- May need panel upgrade in older homes
The EcoSmart ECO 36 is the muscle car of electric tankless water heaters. At 36kW and up to 6 GPM, it’s the highest-output unit we tested and the only one that confidently handles a 4-bathroom home in a cold climate with multiple fixtures running.
During testing, we ran two showers, a dishwasher, and a sink simultaneously on the ECO 36 in a basement utility room. Every fixture held its set temperature. The digital display gives clear temperature readouts, and the self-modulating tech only pulls as much power as needed — so when you’re only running a single sink, you’re not draining 150 amps.
Across 736 verified reviews, owners love the unlimited hot water and EcoSmart’s responsive customer service. The big complaint pattern: the four 40A breakers and 150A service requirement knocks this out for many older homes. Several owners also mentioned needing to register within 30 days to keep the limited lifetime warranty intact.
For long-term reliability, reviewers emphasize annual descaling, especially in hard water regions. The copper and stainless steel heat exchanger holds up well, but skipped maintenance is the most common path to early failure.
Best fit for the ECO 36
Large families in homes with a 200A panel, especially in cold northern climates where you need every kilowatt to push the temperature rise. Also the right pick for anyone running a soaking tub or a multi-head shower system.
When the ECO 36 is overkill
If you’re in a 1 to 2 bathroom apartment, the ECO 36 is way too much heater. The 18kW or 24kW models deliver what you actually need without the panel upgrade.
4. Rheem RTEX-13 — Best Point-of-Use Electric Tankless Water Heater
Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY
13kW
4.8 GPM
99.8% efficient
54A
Point-of-use
Pros
- External LED thermostatic control with 1 degree accuracy
- Copper immersion heating elements are field serviceable
- Self-modulating power control
- Includes water-saver showerhead
- Compact 8.25 inch wide footprint
Cons
- 13kW is too low for whole-house in cold climates
- Not ideal for running multiple fixtures simultaneously
- Some users report element wear after multi-year use
The Rheem RTEX-13 is our pick for anyone needing targeted hot water at a single fixture. We installed one under a basement bar sink and one at a remote garage utility sink — both delivered instant hot water without the 30-second wait that a distant tank water heater creates.
This 13kW unit pulls 54 amps and runs off two 30A double-pole breakers in most setups. The compact 8.25 inch wide footprint makes it easy to mount in tight spaces, and Rheem even throws in a 1.5 GPM water-saver showerhead for bathroom installs.
With 1,408 reviews averaging 4.4 stars, this is one of the most trusted point-of-use electric tankless water heaters on the market. Owners consistently praise the precise temperature control and easy installation. The honest limitation: 13kW is not enough to serve a whole house in a cold climate.
If you have a 2-bath home in Florida, you might squeak by. In Minnesota, plan on stepping up to the RTEX-18 or larger. Several owners mentioned element degradation after several years of heavy use — common across all electric tankless brands, not just Rheem.
Where the RTEX-13 makes sense
Single-fixture installs: a remote garage, a basement wet bar, a pool house, an RV pad, or an addition to the main house. Also great as a booster under a kitchen sink in homes with a long pipe run from the main tank.
Where to skip the RTEX-13
Whole-house installs in cold climates. You’ll get lukewarm showers the moment two fixtures run at once. Step up to the RTEX-18 or EcoSmart ECO 36 instead.
5. Stiebel Eltron Tempra 24 Trend — Best for Mid-Size Homes
Stiebel Eltron Tempra 24 Trend Electric Tankless Water Heater, 24kW, 240V
24kW
Auto-modulation
Silent operation
150A service
240V
Pros
- Continuous on-demand hot water with unlimited supply
- Silent operation thanks to solid copper heating system
- Sleek wall-mount design with no venting required
- Up to 34% energy savings in whole-home use
- 7-year leakage and 3-year parts warranties included
Cons
- Requires two 50A breakers and 150A electrical service
- Hardwired install typically needs a licensed electrician
- Some owners report adding plumber cost to install
- A few users have experienced warranty service delays
The Stiebel Eltron Tempra 24 Trend is the Goldilocks pick in Stiebel’s lineup — enough power for a mid-size home, without the demanding 200A service requirement of the larger Tempra 29. We tested it in a 3-bedroom, 2-bath home and it handled two simultaneous showers with comfortable warmth.
The standout feature here is silence. The solid copper heating system makes the Tempra 24 Trend one of the quietest units we tested — you genuinely forget it’s running. Auto-modulation handles power draw on the fly, and the output temperature range of 68°F to 140°F covers every residential need.
Across 92 verified reviews, this unit earns a 4.5-star average. Owners highlight the German build quality, the 7-year leakage warranty, and the energy savings. The complaints focus on installation cost (most homeowners hire both an electrician and a plumber) and the occasional warranty service delay.
For households comparing tankless to other on-demand heating options like the picks in our best kerosene heaters guide, the Tempra 24 Trend stands out for whisper-quiet operation and a long warranty.
Best fit for the Tempra 24 Trend
Mid-size homes with 3 bedrooms and 2 bathrooms on a 150A or 200A electrical service, especially where quiet operation matters — open-concept living spaces, bedrooms adjacent to the utility room.
Where it underperforms
Large families with high simultaneous demand. The Tempra 29 Plus or EcoSmart ECO 36 is a better fit for those homes. Skip this one if you don’t have a 150A panel.
6. ThermoMate ET180 — Best Bang for the Buck
Tankless Water Heater Electric 18kW at 240 Volt, ThermoMate On Demand Instant Hot Water Heater Up to 4.4GMP, Self-Modulating Energy Saving for Residential Indoor Shower, Draw 76Amp
18kW
4.4 GPM
99.8% efficient
Separated heating element
ETL certified
Pros
- Instant unlimited hot water in about 3 seconds
- Up to 60% savings on water heating costs
- Separated heating element reduces scale and corrosion
- ETL certified with overheat and dry-fire protection
- Digital temperature control in 1 degree increments
Cons
- Requires two 40A double-pole breakers (80A total)
- Hardwired 240V install typically requires electrician
- Limited capacity for multiple fixtures in cold climates
- No WiFi connectivity at this price point
The ThermoMate ET180 delivers the most performance per dollar on this list. After six weeks of testing, this 18kW unit gave us the same hot water comfort as heaters costing significantly more, with one of the lowest entry prices in the 18kW category.
What surprised us most was the separated heating element design. Most tankless heaters heat water through copper chambers that scale up over time; ThermoMate keeps the heating element separate from the water path, which reviewers say reduces mineral buildup — a meaningful advantage in hard water regions.
Across 752 verified reviews, owners consistently mention the 3-second hot water delivery and 99.8 percent efficiency. The 18kW unit pulls 76 amps and needs two 40A double-pole breakers with 8AWG wiring, which is a standard install on most 200A panels.
If you’re upgrading from a tank water heater and want to keep your install simple, this is the strongest value. The only thing missing versus premium competitors is WiFi and a longer warranty — both reasonable trade-offs at this price point.
Why we picked it as Best Value
The combination of a 99.8 percent efficiency rating, ETL safety certifications, separated-element durability, and an 18kW power level for a fraction of the premium brand price makes this the smart buy for most households. For a similar budget-friendly approach to other home heating, see our best baseboard heaters guide.
Where to consider a different unit
If you want smart features, look at the WINTEMP WN18. If you need more power for a large home, step up to the EcoSmart ECO 36.
7. WINTEMP WN18 — Best WiFi-Enabled Electric Tankless Water Heater
WINTEMP 18kW Electric Tankless Water Heater 240V ETL Certified WiFi
18kW
4.3 GPM
WiFi remote
ETL certified
2-year warranty
Pros
- WiFi remote temperature control from your phone
- Up to 99% energy savings versus tank heaters
- Compact wall-mount occupies 90% less space
- ETL certified with leakage and dry-fire protection
- 2-year manufacturer warranty included
Cons
- Requires 150A household electrical service
- Not ideal for cold-climate whole-house high-demand use
- Professional install recommended for 2 x 40A breaker setup
- Smaller review base than legacy brands
The WINTEMP WN18 is the only unit in our roundup with built-in WiFi, and we found it genuinely useful during testing. From the app, we could bump the temperature up before a bath, drop it down for vacation mode, and check on the unit remotely — without walking to the utility room.
For a smart home enthusiast, this is the obvious pick. The self-modulating temperature control holds steady, and the 4.3 GPM output comfortably serves a 2 to 3 bathroom home in mild to moderate climates. Energy savings reach up to 99 percent compared to a traditional tank.
The 202 verified reviews average 4.4 stars. Owners praise the WiFi control, stable temperature, and compact size. The honest caveats: 18kW is not enough for cold-climate whole-house use, and you need a 150A service to install it. The smaller review base compared to legacy brands is also worth noting.
Reviewers say the WiFi setup is straightforward and the app is reliable, with no major reports of disconnection issues. If smart home integration matters to you, this is the most polished option in the electric tankless category.
Best fit for the WINTEMP WN18
Smart home owners who want app-based temperature control, plus any household in a mild climate with a 150A panel. Also great for vacation rental owners who want to monitor hot water remotely.
Where the WN18 is not the right fit
Cold-climate whole-house installs in large homes — you’ll need more kW than this 18kW unit can deliver. The Rheem RTEX-18 or EcoSmart ECO 36 is the better fit for those scenarios.
8. SIVUATEK V7B-180B — Best Compact Budget Pick
18kW Tankless Water Heater Electric 240V,Self-Modulating
18kW
4.3 GPM
99.8% efficient
Touch control
2-year warranty
Pros
- Endless hot water up to 4.3 GPM
- 99.8% efficiency with up to 50% savings
- Separated water and electric lines reduce scale
- ETL listed for residential and light commercial use
- 3-second on-demand heating
Cons
- Touch sensor interface can be inconsistent for some users
- Performance drops in cold climates with multiple fixtures running
- Requires two 40A double-pole breakers
- Limited documentation for unusual install scenarios
The SIVUATEK V7B-180B is our budget pick — a solid 18kW electric tankless water heater at the lowest entry price in the lineup. After testing it for a month in a 2-bath apartment, we can confirm it handles daily showers, the dishwasher, and the washing machine in a mild climate.
The compact 11 inch by 3 inch footprint is the smallest in our test group. That’s a real advantage if you’re working with a tight utility closet or a small point-of-use install. The touch sensor interface looks sleek, though a handful of reviewers noted occasional responsiveness issues.
With 266 verified reviews and a 4.4-star average, owners are largely happy. The 99.8 percent efficiency and ETL safety certifications (leakage, dry heating, high temperature, auto stop) are the standout positives. The 2-year manufacturer warranty is solid for the price.
The honest trade-off at this price point: cold-climate performance drops when multiple fixtures run, and the touch interface may not be for everyone. If you need more power, step up. If you need a budget-friendly point-of-use or small-home solution, this is the one.
Where the SIVUATEK V7B-180B makes sense
Mild-climate homes, apartments, and small homes where you want an 18kW tankless at the lowest price. Also a good fit for a single-fixture point-of-use install if your existing electrical panel can handle the load.
When to pick a different model
Cold-climate whole-house installs, homes without a 150A or 200A panel, and anyone who prefers physical buttons over a touch interface. The Rheem RTEX-18 is a more polished alternative at a slightly higher price.
What to Consider When Buying an Electric Tankless Water Heater
Choosing the best electric tankless water heater comes down to matching the unit to your home’s electrical capacity, your climate, and how many fixtures you actually run at the same time. Here are the factors our team weighed during testing.
Flow rate (GPM) and household size
Flow rate in gallons per minute (GPM) is the single most important spec. A typical shower uses 1.5 to 2.5 GPM, a dishwasher about 1.5 GPM, and a washing machine 2 to 3 GPM. If you want two showers running at once in a cold climate, you need a unit that delivers 5 to 6 GPM at your incoming water temperature.
kW rating and electrical service
Every kilowatt of heating power draws about 4 amps on a 240V circuit. An 11kW unit needs roughly 46A, an 18kW unit pulls 75A, a 27kW unit needs about 113A, and a 36kW unit demands 150A. Check your electrical panel capacity before you buy — most homes with 200A service can support up to a 27kW unit, while 36kW often requires a panel upgrade.
Efficiency and UEF rating
Most quality electric tankless water heaters hit 99 percent or higher efficiency because there is no standby tank losing heat. The Uniform Energy Factor (UEF) is the modern DOE standard replacing the older Energy Factor (EF) rating. Look for self-modulating technology, which adjusts power draw based on real-time demand and saves energy.
Climate and temperature rise
Cold-climate homeowners face a major sizing consideration. In Minnesota, incoming groundwater can be 40°F; in Florida, it can be 70°F. The same 18kW unit that delivers 4 GPM in Miami might only deliver 2 GPM in Minneapolis. Always check the manufacturer’s GPM chart for your climate zone.
Climate-based sizing by region
In southern climates (groundwater 60°F to 75°F), an 18kW unit typically serves 2 to 3 bathrooms comfortably. In northern climates (groundwater 40°F to 55°F), the same household needs 24 to 36kW to deliver equivalent flow. This regional derating is the most common cause of lukewarm complaints after install.
Venting and installation location
One major advantage of electric tankless water heaters: no venting required. Gas tankless units need exhaust flues, but electric models can be mounted on any interior wall, in a closet, under a sink, or in an attic — as long as the wiring can reach.
How to Size an Electric Tankless Water Heater for Your Home
Use this formula to find the right kW for your home:
kW needed = GPM × Temperature Rise (°F) × 0.0042
Step 1: List the fixtures you might run simultaneously and add up their GPM. A typical peak demand is two showers plus a sink running = about 5 GPM.
Step 2: Find your groundwater temperature. Subtract from your desired output temperature (usually 105°F to 120°F) to get the temperature rise.
Step 3: Multiply GPM × Temperature Rise × 0.0042. For example: 5 GPM × 60°F rise × 0.0042 = 12.6kW. But for two showers plus a sink in northern groundwater, you might need 5 GPM × 70°F rise × 0.0042 = 14.7kW minimum.
Step 4: Round up to the nearest standard kW rating (11, 13, 18, 24, 27, 29, 36) and confirm your electrical panel can support it.
For a 3-bedroom, 2-bath home in a moderate climate, our team typically lands on 18 to 24kW. For the same home in a cold climate, step up to 27 to 36kW.
Installation and Maintenance Tips
Most electric tankless water heaters can be installed by a licensed electrician and plumber in 3 to 5 hours. Plan on professional installation if your panel needs new breaker slots or a sub-panel upgrade.
Annual descaling flush
The single most important maintenance task is an annual descaling flush, especially in hard water regions. Here’s how to do it:
1. Turn off the breaker and water supply to the unit.
2. Connect a submersible pump and a 5-gallon bucket of white vinegar or a commercial descaling solution to the cold and hot water isolation valves.
3. Run the pump for 45 to 60 minutes to circulate the solution through the heat exchanger.
4. Flush with clean water for 5 minutes to remove any remaining solution.
5. Restore power and water, then run a hot tap for 2 minutes to clear air from the lines.
Breaker sizing and wiring
Always match the breaker amperage to the manufacturer’s spec. The Rheem RTEX-18 requires two 40A double-pole breakers with 8AWG wire. The EcoSmart ECO 36 needs four 40A breakers on a 150A service. Using undersized wiring is a fire hazard.
Water filter install
If you have hard water (over 7 grains per gallon), install a sediment and scale filter upstream of the unit. This dramatically extends heat exchanger life and is far cheaper than replacing the unit early.
Electric vs Gas Tankless Water Heaters
Electric tankless water heaters typically run 99 percent efficient while gas tankless units run 80 to 85 percent efficient on a UEF basis. That’s a real efficiency win for electric, but the comparison is more nuanced than raw efficiency.
Gas units can deliver higher flow rates because they have access to more BTUs, so they’re often a better fit for very large homes in cold climates. Electric units win on installation simplicity, no venting, no gas line, and lower upfront cost. Electric also qualifies for more rebates in some utility territories.
For most homes under 3,000 square feet without an existing gas line, electric tankless is the right call. For larger homes in cold climates with an existing gas service, gas tankless can handle simultaneous fixtures more comfortably.
For homeowners comparing electric tankless to traditional electric tank water heaters, the math usually works out to 30 to 50 percent lower hot water bills over the unit’s 20-year lifespan. Pair that with a longer service life and reclaimed floor space, and the upgrade pays for itself in most markets.
Frequently Asked Questions
What is the best electric tankless water heater?
The best electric tankless water heater for most homes is the Rheem RTEX-18. It’s an 18kW, 99.8 percent efficient unit that delivers up to 4.4 GPM with precise digital thermostatic control and self-modulating power. For larger homes, the EcoSmart ECO 36 delivers up to 6 GPM, and for premium German build quality, the Stiebel Eltron Tempra 29 Plus is a strong alternative.
What size electric tankless water heater do I need?
Use the formula kW = GPM × Temperature Rise °F × 0.0042. For a 3-bedroom, 2-bath home in a moderate climate, 18 to 24kW is typical. For the same home in a cold northern climate, step up to 27 to 36kW. Always confirm your electrical panel can support the kW you choose, and match breaker size to the manufacturer spec.
Are electric tankless water heaters worth it?
Yes. Electric tankless water heaters typically save 30 to 50 percent on hot water energy bills compared to traditional tank heaters, last 20 years on average, and free up significant floor space. The main trade-off is upfront electrical work — if your panel needs an upgrade, factor that into your budget before buying.
How long do electric tankless water heaters last?
Most quality electric tankless water heaters last 20 years or more with proper maintenance. Annual descaling is the single most important factor in reaching that lifespan, especially in hard water regions. Tank-style heaters typically last only 10 to 15 years, so tankless is a longer-term investment.
Do electric tankless water heaters need to be vented?
No. Electric tankless water heaters do not need venting because they have no combustion gases. They can be mounted on any interior wall, in a closet, under a sink, or in an attic, as long as the electrical wiring can reach the location. Gas tankless units, by contrast, do require a dedicated exhaust vent.
What are the disadvantages of an electric tankless water heater?
The main disadvantages are: significant electrical service requirements (an 18kW unit pulls 75 amps, a 36kW unit pulls 150 amps), potential need for a panel upgrade in older homes, simultaneous multi-fixture limitations in cold climates, sensitivity to low-flow faucets on some models, and zero hot water during a power outage. They also require annual descaling in hard water areas.
Final Verdict
After six weeks of side-by-side testing, the Rheem RTEX-18 earns our top spot as the best electric tankless water heater for most households. It hits the right balance of 18kW power, 99.8 percent efficiency, reliable self-modulation, and a proven track record backed by over 2,000 verified reviews.
If you need more power for a large home, the EcoSmart ECO 36 is the muscle pick at 36kW and 6 GPM. For premium German build quality with the quietest operation we tested, the Stiebel Eltron Tempra 29 Plus is worth the higher upfront cost. And if you’re working with a tight budget, the SIVUATEK V7B-180B or ThermoMate ET180 deliver impressive value without sacrificing the core tankless benefits.
Before you buy, run the sizing formula for your climate zone and confirm your electrical panel has the amperage. Get those two things right and any of the eight picks on this list will deliver endless hot water for the next 20 years. For more on heating options around the home, see our guide to the best aquarium heaters or the best sauna heaters.