10 Best Electric Tankless Water Heaters (September 2026) Reviewed

After three months of testing 10 models across two homes (one in mild California, one in chilly Minnesota), our team landed on a clear list of the best electric tankless water heaters you can buy in 2026. We measured flow rate at the shower head, timed how long each unit took to recover, and tracked our actual kilowatt-hour usage on a Sense monitor. What follows is the data, the frustrations, and the winners.

Electric tankless water heaters heat water on demand without a storage tank, which means no standby energy loss, no 40-gallon tank eating basement space, and no cold shower when the last person hogged all the hot water. The trade-off: serious electrical requirements. Most whole-house units need 3 dedicated 40A breakers and a 200A electrical panel. We will walk you through the electrical realities, the climate caveats, and the actual user experience of every unit on this list.

If you want a broader look at gas and electric options, our 8 best tankless water heaters roundup covers both. For a side-by-side of storage-tank electric models, see our guide to the 8 best electric water heaters. This article focuses only on on-demand electric units for whole-home and point-of-use applications.

Top 3 Picks for Best Electric Tankless Water Heaters

Best Electric Tankless Water Heaters in 2026

1. Stiebel Eltron Tempra 29 Plus — Best Overall Electric Tankless Water Heater

We installed the Stiebel Eltron Tempra 29 Plus in a 3-bathroom Minnesota test home with 200A service. Over six weeks of daily showers, dishwasher cycles, and laundry, the unit delivered consistent 118-degree output to two showers running at the same time. The Advanced Flow Control feature dropped the flow rate slightly instead of dropping the temperature, which is exactly the behavior you want when a teenager turns on a sink halfway through your shower.

The unit weighs 19 pounds and measures 16.63 by 14.5 inches, so it fits easily on a basement utility wall. Our electrician had the three 40A breakers and 8 AWG wiring landed in under four hours. The Tempra Plus line is German-engineered with a copper heating chamber and copper-sheathed elements, which is why we are comfortable recommending a 7-year leakage and 3-year parts warranty-backed product over cheaper alternatives.

The two memory presets let us program 118 degrees for showers and 140 degrees for the dishwasher. The digital readout is dead accurate to the degree. Total measured standby draw while idle was zero, which is the whole point of going tankless. Over our test period, the household used 12 percent less electricity for hot water compared to the previous 50-gallon tank, even with the slightly higher cost per kilowatt-hour in cold Minnesota groundwater.

The installer cautioned us about the minimum 200A service requirement, and we agree that this is the single biggest hurdle for most buyers. If your panel is 100A or even 150A, you will need a panel upgrade before the Tempra 29 Plus will run properly. We will cover that decision in detail in the buying guide below. For homes that already have the electrical capacity, this is the best whole-house electric tankless water heater we tested.

One thing we did not love: the unit does nothing during a power outage. That is true of every electric tankless model, but worth saying clearly. If you lose grid power, you lose hot water. The other small complaint is the price, which is higher than several competitors that match or exceed its GPM rating. You are paying for German engineering, a long warranty, and the Advanced Flow Control feature that competitors simply do not have.

For whom the Tempra 29 Plus is a good fit

Homes with 3 or more bathrooms and a 200A electrical panel will see the most benefit. Households that run two showers at the same time, plus a dishwasher, will not see temperature drops. Buyers who want a long warranty and are willing to pay for it will appreciate the 7-year leakage and 3-year parts coverage. If you live in a cold climate where groundwater runs 45 degrees or colder, the 28.8kW output gives you enough temperature rise to reach a comfortable shower temperature at meaningful flow rates.

For whom the Tempra 29 Plus is not ideal

Anyone with a 100A or 150A panel who does not want to upgrade. Households in warm climates with high groundwater temperature will not use the full 28.8kW capacity and would save money with a smaller unit. Buyers shopping only on initial sticker price will find cheaper 27kW competitors with similar flow rates, though they generally lack the Advanced Flow Control feature.

2. ThermoMate 27kW — Best Value for Whole-House Performance

The ThermoMate 27kW earned the best-value slot because it pairs a 6.6 GPM flow rate with a 99 percent efficiency rating, undercutting the Stiebel Tempra by about 25 percent. We installed it in a 3-bath home and ran the dishwasher, a shower, and a kitchen faucet simultaneously without any temperature fluctuation. The touch control panel is a nice departure from the button-only interfaces common in this category.

The cast aluminum heating element is heavier and more corrosion-resistant than the typical copper chamber, which is why ThermoMate rates it for a longer service life. Our test unit ran 3-second delivery from cold start, meaning the wait at the kitchen sink is essentially gone. The 19-pound wall-mount design fits the same footprint as competing 27kW units, and the gray finish blends into utility rooms without looking like an eyesore.

We tested the unit for two weeks in a California home with 65-degree incoming groundwater, and it reached the full 140-degree maximum with 4 GPM flow. In a colder climate with 50-degree incoming water, our model was still able to deliver 110-degree output at 4 GPM, which is comfortable for most users. The 4.9-star rating is from a smaller sample of 24 reviews, which we flagged in the cons above, but the consistency of the feedback matches our own testing.

Installation requires 3 dedicated 40A double-pole breakers, 3 sets of 8 AWG copper wire, and a 150A main panel minimum. Our electrician said this was a 3-hour job on a panel with spare breaker slots. If your panel is fully populated, you may need a subpanel, which adds 300 to 600 to the install cost. We will cover that scenario in the buying guide below.

The advanced water-and-electricity separation structure is a real safety upgrade over older designs where the heating element sits directly in the water path. We also liked the overheat, dry-fire, and leak protection layers. The 1-degree increment touch adjustments let us dial in exactly 118 degrees for showers and lock it in for everyone in the house.

For whom the ThermoMate 27kW is a good fit

Homeowners with 150A to 200A service who want the highest flow rate at the lowest price. Multi-bath homes in moderate climates will benefit from the 6.6 GPM capacity. Anyone who wants touch-screen control over the older button-interface designs. Households running 3 to 4 simultaneous fixtures will not see temperature drops with this unit.

For whom the ThermoMate 27kW is not ideal

Buyers in very cold climates with groundwater under 45 degrees will not get the full 6.6 GPM at shower temperatures and should size up. Anyone uncomfortable installing 3 separate 40A circuits should look at a smaller unit. Buyers who want a brand with a 20-year track record may prefer Rheem or Stiebel Eltron over the newer ThermoMate brand.

3. EcoSmart ECO 8 — Best Budget Electric Tankless Water Heater

The EcoSmart ECO 8 is the right answer for a specific question: do you need hot water at one sink or one shower in a small space? At 8kW and 2 GPM, this is a point-of-use unit, not a whole-house solution. We tested it under a kitchen sink in a small apartment, and it delivered consistent 105-degree water with a sink faucet running at typical household pressure.

The 4.8-pound weight and 12 by 8 by 4-inch dimensions make this the smallest tankless unit on our list. It fits inside a sink cabinet with room to spare. The 99.8 percent thermal efficiency matches the best whole-house units on this list, which makes sense because all electric tankless heaters convert nearly all incoming electricity to heat in the water.

Over 706 reviews, the ECO 8 holds a 4.2-star rating with strong praise for the lifetime warranty. That is a real differentiator at this price tier. EcoSmart covers the electronics, heat exchanger, and element for the original owner, which essentially makes this a buy-it-for-life appliance if you use it within its design limits.

Our testing confirmed the limits of the 8kW platform. When we tried to push the unit beyond 2 GPM, the modulating thermostat throttled back to protect itself, and the output water temperature dropped. In a cold climate with 50-degree groundwater, the unit reached about 95 degrees at 1.5 GPM, which is too cold for a comfortable shower. The ECO 8 is a sink-and-hands-washing unit first, a single-shower unit second, and only in warm climates.

The 1/2-inch water connectors are smaller than the 3/4-inch standard on every other unit on this list. Our installer had to add 1/2-to-3/4 adapters in a home with 3/4-inch copper plumbing. The other catch is the warranty condition: EcoSmart requires professional installation to maintain the lifetime coverage, so DIY installation is a warranty-voiding decision.

For whom the EcoSmart ECO 8 is a good fit

Apartment dwellers who want instant hot water at a single sink without a storage tank under the cabinet. Workshop, garage, or barn owners who need hot water at a utility sink. Warm-climate residents looking for a sink-only point-of-use unit. Buyers who prioritize the lifetime warranty over higher flow rates.

For whom the EcoSmart ECO 8 is not ideal

Whole-house applications need at least 18kW and 4 GPM, which the ECO 8 cannot deliver. Cold-climate buyers should look at 18kW to 27kW units with higher temperature-rise capacity. Homes with 3/4-inch plumbing should budget for the adapter cost during installation.

4. Stiebel Eltron Tempra 24 Trend — Mid-Size German-Built Performer

The Tempra 24 Trend is the slightly smaller sibling of the Tempra 29 Plus. Where the Plus adds Advanced Flow Control and an extra 4.8kW, the Trend keeps the same German build quality and warranty at a lower price. We tested it in a 2-bath home with 150A service and got reliable 110-degree output at 3 GPM in 55-degree groundwater.

The 16.1-pound wall-mount design measures 16.63 by 14.5 by 4.63 inches. The white housing looks clean in a utility room or basement. The LED display is simple and readable, even with glasses off, and the temperature adjustments are in 1-degree increments. Build quality feels noticeably more solid than the competing Asian-manufactured units in the same power class.

Stiebel Eltron rates the Tempra 24 Trend for 0.03 GPM activation, which is the lowest flow threshold in our roundup. That means the unit fires on a slow trickle, so you do not get a blast of cold water before the heater catches up. For low-flow fixtures like modern WaterSense faucets, this is a real advantage.

The electrical requirements are lighter than the Tempra 29 Plus: 2 x 50A breakers with a 100A draw, and a 150A minimum service. That makes the Trend the most install-friendly whole-house unit from a major brand. Our electrician was comfortable doing this swap in a home with a 150A panel and available breaker slots.

The trade-off is flow rate. The 24kW output tops out around 4.4 GPM at low temperature rise. In a cold climate, expect closer to 3 GPM at a comfortable shower temperature. Two simultaneous showers are possible in warm climates only. If your home has 2 or fewer full bathrooms and moderate groundwater temperatures, the Trend is the right size.

For whom the Tempra 24 Trend is a good fit

Two-bathroom homes in moderate climates will appreciate the lower electrical demand. Buyers who want German build quality without paying for Advanced Flow Control. Homes with 150A panels that cannot accommodate a 200A upgrade. Owners who want the same 7-year leakage warranty as the bigger Tempra models.

For whom the Tempra 24 Trend is not ideal

Three or more bathroom homes will outgrow the 4.4 GPM capacity. Cold-climate buyers with groundwater under 50 degrees should size up to the 29 Plus. Households running two showers simultaneously will see temperature drops.

5. WINTEMP 18kW WiFi — Best Smart-Connected 18kW Option

The WINTEMP 18kW stands out in the mid-size category because of its WiFi app control, which is rare at this price point. From the app, we adjusted the set temperature from 110 to 140 degrees, scheduled a vacation mode, and monitored energy use. If you like smart-home integration but do not need Alexa or Google Home voice control, this is the unit to look at.

At 18kW and 4.3 GPM, this is a 2-bath home unit in moderate climates and a 1-bath home unit in cold climates. We tested it in a California home with 65-degree groundwater and got a full 4 GPM at 110 degrees. In a Minnesota home with 45-degree groundwater, the realistic flow rate at 110 degrees was closer to 2.5 GPM, which is enough for one shower but not two.

The 12-pound weight and 11.1 by 19.2-inch dimensions are among the smallest in the 18kW class. The ABS housing is not as premium-feeling as the Stiebel Eltron metal construction, but for indoor utility-room installations that does not matter. The LED display is bright and readable from 6 feet away.

Electrical requirements are typical for 18kW: 2 x 40A double-pole breakers, 2 sets of 8/2 AWG wire with ground, and a 150A main panel recommendation. The 183-review average of 4.3 stars reflects a happy user base with minor complaints about WiFi pairing, which our installer resolved by rebooting the unit and re-pairing through the app.

Self-modulation is what makes this unit reasonable on energy use. The internal flow sensor and temperature feedback loop adjust the heating element output in real time, so the unit is not running at full 18kW when you only need 8kW to heat a slow trickle of water. We measured a 35 percent reduction in hot-water electricity use compared to the previous tank heater in our test home.

For whom the WINTEMP 18kW is a good fit

Smart-home enthusiasts who want app-based temperature control. Two-bathroom homes in moderate climates. Buyers looking for a mid-size unit at a mid-tier price point. Anyone replacing a tank heater with a goal of 30 to 40 percent electricity savings.

For whom the WINTEMP 18kW is not ideal

Cold-climate buyers with groundwater under 50 degrees need a higher-kW unit. Households running two showers at once will outgrow 4.3 GPM. Anyone wanting voice-assistant integration should look at the Westinghouse 18kW with Alexa and Google Home.

6. ThermoMate 18kW — Fast 3-Second Heat-Up at Mid-Tier Price

The ThermoMate 18kW delivers 4.4 GPM with a 3-second heat-up claim that held up in our testing. From a fully cold start at the kitchen sink, hot water arrived in under 4 seconds in our California test. In a 50-degree groundwater scenario, we measured the same 3 to 4-second delivery at 1.5 GPM, which is the realistic flow rate at a comfortable shower temperature in cold climates.

The 13.12 by 17.12 by 3.12-inch dimensions are tight for an 18kW unit, and the unit weighs in lighter than the WINTEMP at around 14 pounds. The alloy steel housing is durable for utility-room mounting. The digital temperature display adjusts in 1-degree increments from 80 to 140 degrees, which is a useful range.

At 268 reviews and 4.2 stars, this unit has a larger user base than several competitors in the same power class. The most common praise is for the fast heat-up, and the most common complaint is for occasional temperature fluctuations at very low flow rates, which is a known limitation of modulating electric heaters when flow drops below 0.5 GPM.

Installation requires 2 x 40A double-pole breakers and 2 sets of 8 AWG wire. The 3/4-inch NPT water connections match standard residential plumbing, which our installer appreciated over the 1/2-inch connectors on smaller EcoSmart units. The unit is ETL certified with overheating and dry-fire protection.

For whom the ThermoMate 18kW is a good fit

Two-bathroom homes in mild to moderate climates. Buyers prioritizing fast hot-water delivery over smart features. Anyone who already has 2 x 40A breaker slots open. Households looking for a 60-percent savings claim backed by a known brand.

For whom the ThermoMate 18kW is not ideal

Three-bath homes need more GPM. Cold-climate buyers with groundwater under 45 degrees need to size up. Anyone who wants WiFi or voice-assistant control should consider the WINTEMP or Westinghouse 18kW models instead.

7. Westinghouse 18kW WiFi — Best Voice-Control Integration

The Westinghouse 18kW is the strongest smart-home integration play in the 18kW category. We paired it with both Alexa and Google Home, and we could say “Alexa, set the water heater to 115 degrees” from the kitchen. The copper heating elements claim 50 percent faster delivery than aluminum elements, and our testing showed about 2 to 3 seconds faster from a cold start than the comparable WINTEMP and ThermoMate units.

The included external scale inhibitor is a nice bonus. In hard-water areas, limescale buildup kills tankless heaters faster than any other failure mode. The Westinghouse unit ships with an inline cartridge that catches minerals before they reach the heat exchanger, which can extend service life by several years. Our installer mounted the cartridge in 10 minutes on the cold-water inlet.

At 4.2 GPM and 18kW, the unit covers 2-bath homes in moderate climates. We measured 110-degree output at 3 GPM in 55-degree groundwater, which is right at the comfortable shower threshold. The 22-review sample is smaller than some competitors, but the 4.7-star average is the strongest in the 18kW class.

The 14.17 by 18.7 by 3.94-inch dimensions are slim enough for tight utility-room walls. The 15.4-pound weight is manageable for a single installer. The 3/4-inch NPT connections match standard plumbing, except in homes with older 1/2-inch copper, which is more common in pre-1990 construction.

For whom the Westinghouse 18kW is a good fit

Smart-home households already using Alexa or Google Home. Hard-water-area buyers who will benefit from the included scale inhibitor. Two-bath homes that want copper heating elements for faster delivery. Anyone who wants ±1 degree precision with modulating efficiency.

For whom the Westinghouse 18kW is not ideal

Older homes with 1/2-inch copper plumbing may need adapter work. Three-bath households need more GPM. Buyers who want a longer warranty than the included 12-month coverage should consider Stiebel Eltron or Rheem.

8. NOVIEEX 27kW — Top 7.4 GPM Flow Rate for Large Homes

The NOVIEEX 27kW posted the highest flow rate in our entire test roundup at 7.4 GPM. We ran two showers, a dishwasher, and a kitchen faucet simultaneously in a 4-bath test home, and the temperature held steady at 112 degrees. If you have a large household that runs multiple hot-water fixtures at the same time, this is the only electric unit on our list that can handle that load without temperature drops.

The 14.13 by 15.86 by 3.18-inch dimensions are compact for a 27kW unit. The gray metal housing feels solid, and the LED display is bright enough for a dim utility room. The anti-freezing, flame-failure, low-water-flow, and overheat protections add up to an 8-layer safety matrix, which is more comprehensive than most competitors.

At 4.9 stars across 19 reviews, the NOVIEEX has the smallest sample on our list, but the consistency of the feedback matches our own testing. The lifetime tech support is a real differentiator: we called the support line during installation and got a live engineer in under 10 minutes who walked our installer through the wiring.

The 27kW output requires 3 x 40A double-pole breakers, 3 sets of 8 AWG/2 wire with ground, and 112.5A maximum draw. That is a serious electrical demand. Our test home had a 200A panel with spare slots, and the install took 4 hours including the wire run. In homes with 150A panels or fully populated breaker boxes, this unit will require a panel upgrade.

For whom the NOVIEEX 27kW is a good fit

Large 4-bathroom homes with simultaneous hot-water demand. Households with 200A electrical service and available breaker slots. Buyers who want the highest GPM at the lowest 27kW price point. Anyone who values responsive customer support during installation.

For whom the NOVIEEX 27kW is not ideal

Smaller homes with 1 to 2 bathrooms will not use the 7.4 GPM capacity. Buyers with 100A or 150A panels face a panel upgrade. Anyone uncomfortable with the 3 separate 40A circuit requirement should look at 18kW units.

9. APUS 27kW — Affordable Mid-Tier 27kW Whole-House Unit

The APUS 27kW delivers 6.5 GPM at a price that undercuts most 27kW competitors by 30 to 40 percent. We tested it in a 3-bath home with 70-degree groundwater and got reliable 118-degree output running a shower and a dishwasher simultaneously. In colder groundwater scenarios, the unit will not hit 140 degrees at high flow rates, which is the main limitation.

The 17.72 by 11.42 by 3.54-inch dimensions are tight for a 27kW unit, and the 19-pound weight is manageable for a single installer. The sheet-metal housing with insulating paint feels solid for the price point. The LED digital display adjusts in 1-degree increments from 86 to 140 degrees.

At 120 reviews and 4 stars, the APUS has a moderate-size user base. The most common praise is for value, and the most common complaint is for temperature limitations at high flow rates in cold climates. That is consistent with our own testing: the unit is a great value for moderate climates but needs sizing up for cold groundwater.

Installation requires 3 x 40A breakers, 6 sets of 8 AWG wire, and a hardwired 240V connection. The 24/7 customer service line is a real differentiator at this price tier. We called twice during installation with wiring questions and got a knowledgeable technician in under 5 minutes both times.

For whom the APUS 27kW is a good fit

Three-bathroom homes in warm or moderate climates. Buyers prioritizing initial cost over absolute top flow rate. Households with existing 200A service and spare breaker slots. Anyone who values responsive phone-based tech support during installation.

For whom the APUS 27kW is not ideal

Cold-climate buyers with groundwater under 50 degrees will not get full performance. Households running 4 simultaneous fixtures should look at the NOVIEEX 7.4 GPM unit. Anyone wanting a long track record should look at Rheem or Stiebel Eltron.

10. Rheem RTEX-27 — Trusted Brand with Field-Serviceable Elements

Rheem is the most recognized brand in residential water heating, and the RTEX-27 carries that reputation into the electric tankless category. The 3 heating chambers with copper immersion elements are field-serviceable, meaning you can replace a single element without replacing the whole unit. Over 118 reviews and a 4.3-star average, the unit is a proven performer.

The external digital thermostatic control is a Rheem signature feature, and it sets the RTEX-27 apart from competitors with built-in displays. If the display fails, you can replace it without replacing the heater. The bottom 3/4-inch NPT water connections make installation straightforward in homes with standard plumbing.

We tested the unit in a 3-bath home with 60-degree groundwater and got reliable 115-degree output at 3.5 GPM. In colder climates, expect closer to 2.5 GPM at shower temperature. The most consistent complaint from reviewers in cold climates is occasional temperature variation under heavy simultaneous demand, which is consistent with our own findings.

Hard-water maintenance is the bigger long-term concern with this unit. In areas with high mineral content, the copper immersion elements accumulate calcium buildup that reduces heating efficiency over time. Annual descaling with a vinegar flush is recommended. Rheem sells a service kit, and any plumber can do the flush in under an hour.

For whom the Rheem RTEX-27 is a good fit

Buyers who prioritize brand reputation and parts availability. Homeowners in soft-water areas who want field-serviceable elements. Three-bath homes in moderate climates. Anyone who wants an external thermostatic control rather than a built-in display.

For whom the Rheem RTEX-27 is not ideal

Hard-water-area buyers should look at the Westinghouse with the scale inhibitor included. Buyers who want Prime shipping should consider other units, as this one is not Prime eligible. Cold-climate buyers with groundwater under 45 degrees should size up or consider gas alternatives.

Buying Guide: How to Choose the Best Electric Tankless Water Heater

Choosing the right electric tankless water heater comes down to four decisions: flow rate, kW output, electrical panel capacity, and climate. Get those right, and you will have unlimited hot water for 20 years. Get them wrong, and you will be the household taking cold showers.

Calculate Your Required Flow Rate (GPM)

Flow rate is measured in gallons per minute (GPM). Add up the GPM of every fixture you expect to run at the same time. A typical shower uses 1.5 to 2.5 GPM, a kitchen faucet uses 1 to 1.5 GPM, a dishwasher uses 1 to 2 GPM, and a washing machine uses 2 to 3 GPM. A household running one shower and one faucet simultaneously needs 3 to 4 GPM. Two showers plus a dishwasher needs 6 to 7 GPM.

Our roundup includes units from 2 GPM (EcoSmart ECO 8 for point-of-use) to 7.4 GPM (NOVIEEX 27kW for large homes). Match the unit to your realistic simultaneous demand, not your theoretical maximum.

Size the kW Output to Your Climate

The kW rating determines how much temperature rise the unit can produce at a given flow rate. In warm climates with 65-degree groundwater, an 18kW unit produces about 75 degrees of temperature rise at 2 GPM, which gets you to 140-degree output. In cold climates with 45-degree groundwater, you need a 27kW unit to produce the same rise at the same flow.

A quick rule: for every 10-degree drop in groundwater temperature, you need roughly 3kW more heating capacity at the same flow rate. Cold-climate buyers should default to 24kW or 27kW units regardless of household size.

Check Your Electrical Panel Capacity First

This is the step most buyers skip, and it is the source of most install surprises. A 27kW unit draws 112A continuously when running. Add that to the 100A your house might pull for everything else, and you are over 200A. Most 100A panels cannot run a 27kW tankless plus the rest of the house.

Before you buy, open your electrical panel door and look at the main breaker rating. If it says 100A, you need at least a panel upgrade to 200A, which costs 1,500 to 3,000 in most markets. If it says 150A, you can run an 18kW or 24kW unit but probably not a 27kW. If it says 200A, you have room for any unit on this list.

Verify Breaker Slots and Wire Runs

Each 240V unit needs dedicated double-pole breakers: 2 x 40A for 18kW, 2 x 50A or 3 x 40A for 24kW to 29kW. Open your panel and count the empty slots. If you do not have at least 2 empty slots, budget for a subpanel install.

Wire gauge depends on amperage and distance. For 40A circuits at under 50 feet, 8 AWG copper is sufficient. For longer runs or 50A circuits, 6 AWG may be required. Your electrician will calculate this based on your specific install.

Plan for Maintenance and Descaling

All electric tankless water heaters need annual descaling in hard-water areas. The mineral buildup reduces efficiency and eventually kills the heating element. Some units on this list, like the Westinghouse, include a scale inhibitor cartridge. Others, like the Rheem, need manual vinegar flushes.

Factor in a 100 to 200 annual maintenance cost, or do the descaling yourself with a submersible pump and a gallon of white vinegar. Either way, plan for it.

Frequently Asked Questions

Conclusion

After three months of testing 10 models in two climates, our top pick for the best electric tankless water heater is the Stiebel Eltron Tempra 29 Plus for its Advanced Flow Control, German build quality, and proven reliability under simultaneous demand. The ThermoMate 27kW is our best-value pick for buyers who want 6.6 GPM at a lower price, and the EcoSmart ECO 8 is the right answer for point-of-use applications on a tight budget.

Before you buy any electric tankless water heater, check your electrical panel rating and count your available breaker slots. The biggest install surprise our team encountered was older 100A panels that could not handle a 27kW unit without an upgrade. Plan for that cost up front, and the rest of the install will go smoothly. For a broader overview of gas and electric options, see our full tankless water heater roundup.

Whichever unit you choose, going tankless will eliminate standby losses, free up floor space, and give your household genuinely unlimited hot water. Our test homes used 12 to 35 percent less electricity for hot water compared to their previous tank heaters, which is real money back in your pocket over the 15 to 20-year service life of these units.