Unlike a conventional storage-type system, a tankless water heater does not store any hot water. Instead, the heating is instantaneous which provides for greater energy efficiency (up to 30%) due to the complete absence of standby losses.
Only paying for hot water that you are using will save you money in the long run. And that’s not all. You also get an endless supply of hot water and a tankless water heater requires very little space.
The advantages that electric has over gas are that the former is cheaper to purchase & install, it operates more efficiently, it lasts longer, and you don’t have to worry about venting.
But how do you find the best electric tankless water heater? Don’t worry, we’ve got you covered!
On This Page You Will…
|Model||Our Rating||Price||Type||Power||El. Service|
Best Rated Electric Tankless Water Heater for Whole Houses: Stiebel Eltron Tempra 24 Plus
|$$$$||Whole House, 240 V||2x 12 kW||2x 50 A Breakers|
Best Seller: EcoSmart ECO 18 (Whole House)
|$$$||Whole House, 240 V||2x 9 kW||2x 40 A Breakers|
Cheapest Whole House Electric Tankless Water Heater: Hyperikon
|$$||Whole House, 240 V||3x 9 kW||3x 50 A Breakers|
Best Point-of-Use Electric Tankless Water Heater: Rheem RTEX-13
|$$||Point of Use, 240 V||2x 6.5 kW||1x 60 A Breaker|
Best Selling POU Water Heater: EcoSmart ECO 11
|$||Point of Use, 240 V||2x 5.5 kW||1x 60 A Breaker|
Our #1 120 V (110 V) Heater: Stiebel Eltron DHC 3-1
|$||Point of Use, 120 (110) V||1x 3 kW||1x 25 A Breaker|
Before we get started with what you should consider when buying an electric tankless water heater (ETWH), we wanted to mention real quick that whether you call them tankless, on demand, instant or instantaneous, they all describe the same thing: Water is heated only when needed which has a number of advantages listed above.
With that in mind, “instant” does not mean that you will not have cold water sitting in the line to your bathroom sink when you wake up in the morning. Even with a tankless heater this cold water must be flushed first before you get the warm.
If you want truly instant hot/warm water you should look into recirculation which requires an extra pump and a recirculation line where appropriate (more on this matter below).
Choosing the best tankless electric water heater always starts with sizing.
Your ideal system size depends on how many people live in your home, their water using habits, and also how many bathrooms and hot-water appliances you have.
Simply put, small, medium or large depends on how much hot water you need at times of peak consumption. If you go too small, hot water will be limited, so you either have to use less or it won’t be as warm. Going too large means overspending.
We also have to differentiate between point-of-use (POU) and whole house units. The former may feature no more than a single heating element while the latter comes with 2, 3 or even 4.
Another very important factor when sizing a water heater is where you live in the country which translates to feed water temperature. Because if you live in a colder climate the temperature rise that’s needed is naturally higher.
The southern states have warmer input water, but if you live in the north and it’s winter, you might not be able to run more than one shower without experiencing a loss in temperature or flow.
So as a general rule, the farther north you live, the larger a water heating system you need.
Pro tip: Refer to the sizing chart provided by most of the manufacturers. This will help you determine which system size is the best fit. Just remember to take the information with a grain of salt. Some companies tend to exaggerate with what their systems can do…
For comparability, in each review we tried to quote how many gallons of water a system provides at 105 °F which is considered the upper end of the temperature range most comfortable for showering.
First of all, most DIYers might say that installing an ETWH is simple. However, if you don’t know what you are doing you should definitely not try to do this yourself just to save a few bucks. It’s simply too dangerous and not worth the risk.
Also, with some manufacturers their systems must be installed by licensed contractors or else the warranty will void.
Another thing to bear in mind is that not every home is suited for a whole house unit, simply because the amp draw would be too high. The Stiebel Eltron Tempra 24 Plus (reviewed below), for example, requires 2 separate dedicated 50A breakers and a minimum of 150A electrical service. And the even larger 36 Plus requires a 300A main service.
“But I thought that a tankless water heater does nothing 99% of the time!” That’s correct, but when it needs to heat it has to do so much more quickly which requires more power (and more heating elements).
This could mean that you have to upgrade your old electrical service panel with bigger wires and bigger breakers, or you have to run a completely new one entailing a couple of thousand dollars worth of electrical work.
Now, again, this is for large whole house water heaters and there are many smaller ones available.
By the way, your electrical breaker box that can usually be found outside the house will tell you the amps that your house was wired with. If you can’t find it or you want to be on the safe side, ask your electrician.
Plumbing & Electric Codes
Keep in mind that your water heater installation must comply with all applicable national, state and local plumbing and electric codes.
Tankless water heaters last much longer than regular tank heaters if properly maintained. 15 to 25 years can be reasonable if you remember to delime regularly. Deliming means to remove possible scale residues that stick to the heating elements when they are used to heat hard water.
Another option would be to install a water softener upstream of the heater.
What about energy efficiency? Well, it turns out that this plays a minor role when choosing a new ETWH, since they are all highly energy efficient (at least 95 percent).
For more information you can refer to a system’s Energy Factor (EF). It rates the energy conversion efficiency. A higher factor equals higher efficiency.
Order of Reviews
We will begin this tankless electric water heater review series with the best rated model currently available on the Amazon marketplace: The Stiebel Eltron Tempra 24 Plus, designed for whole house use (apartments are fine too) and light commercial applications.
Most importantly, how much hot water can the Tempra 24 Plus provide? Enough for up to 2 showers to run simultaneously:
Not enough water? Well, the Stiebel Eltron Tempra line features many different models, some less and some more powerful than the 24 Plus. That being said, the 24 Plus is currently the most popular.
Anyway, if you need more water check out the 29 or 36 Plus. For example, the 36 Plus which is the largest unit supplies up to 5.45 gpm at 59 °F feed water and 105 °F output water temperature.
You have to keep in mind, though, that it requires 300 amps electrical service (3x 50A breaker) minimum, says Stiebel Eltron. The 24 Plus, on the other hand, requires only 2 separate dedicated 50A breakers and a minimum of 150A electrical service.
It’s probably best if you take a look at the sizing chart here.
But no matter which version you choose, they all have the same size and will deliver any water temperature between 86 to 140 °F – only at different flow rates.
You can set the desired temperature using the large knob on the front cover. Both °F and °C scales are available. By the way, the system is really quiet, and easy to use also thanks to the large backlit display that shows the output temp.
How about the installation?
Like we said, if you don’t know what you are doing, we definitely recommend you hire a licensed technician. In fact, the manual states that this water heater “must be installed by a licensed electrician and plumber“. Furthermore, “Failure to comply with the installation and operating instructions or improper use voids the warranty.”
Customers that did install the system themselves said it was simple.
In terms of maintenance, it is recommended to remove scale and dirt that may build up at the screen in the cold water inlet from time to time – easy.
The Tempra Plus series has been extremely well received and there isn’t really much that we don’t like, except for the high price tag, of course.
Just a couple of issues that a handful of users had:
Stiebel Eltron’s Tempra Plus water heaters and the Tempra 24 Plus in particular do exactly what they are supposed to do: Deliver continuous hot water whenever you need it. Solid, excellent performance and large enough to heat all hot water applications of an entire house. This is the best electric tankless water heater out there in our opinion. 4.5 stars!
Next, we are going to take a look at the best selling ETWH at the time of writing this guide, namely the EcoSmart ECO 18.
Just like the Stiebel Eltron Tempra reviewed above, the EcoSmart ECO is available in a variety of sizes. The main difference between the two water heater series, however, is that the latter is much more affordable.
ECO 18, 24, 27 and 36 is what EcoSmart recommends for larger apartments, condominiums or townhomes, whereas the smaller ECO 11, for example, is for residential or commercial point-of-use applications.
Being the most popular, the ECO 18 can provide enough water for a single shower, maybe a shower and a faucet, depending on where you live in the country:
Now, this might not be enough water for you and your family. In this case, there is the larger ECO 27 or ECO 36. The latter can provide up to 5.3 gallons per minute (estimated) at 59 °F input water temperature and 3.7 gpm at 39 °F.
For more info, check out the sizing chart included in the product description.
System size has no effect on the min/max temperature that you can set. The lower end is 80 °F, the upper end 140 °F. Simply use the large front knob to choose your desired temperature in 1-degree increments – child’s play!
What’s more, the self-modulating feature allows all ECO water heaters to adjust their energy input based on how much hot water is needed. In other words: No more energy is used than necessary for the current demand. Good for the environment and your wallet.
One advantage that this water heater has over the Stiebel Eltron Tempra is that it activates at 0.25 gpm water flow rather than 0.5 gpm. This means that it’s not as sensitive and won’t shut off producing a cold water rush if you slightly turn down the hot water while showering.
And last but not least, we have an UL Standard 499 safety certification, an ETL listing, and all EcoSmart ECOs are tested and certified against NSF Standard 372 for lead-free compliance.
Limited lifetime warranty? Check! (Requires registration within 30 days of purchase + installation by licensed professional)
Browsing dozens of customer reviews we stumbled upon 2 issues, although both were quite rare:
And while some reviewers said that tech support was “easy to reach” and replacement parts were shipped promptly, some complained that they could not get hold of a service representative or that they were difficult to work with.
Another difference to the Tempra is that EcoSmart ECOs are manufactured in China. Tempras are Made in Germany.
For most users, the EcoSmart ECO 18 and its siblings have been doing great: Consistently hot water combined with great energy savings. On top of that, the price is hard to beat. 4 stars!
Next in line is the Rheem RTEX-18. It’s a popular alternative to the EcoSmart providing 2 gallons per minute at a temperature increase of 62 °F, 3 gpm at 41 °F, and 1.5 gpm at 82 °F. This makes it comparable to the EcoSmart ECO 18.
One difference, however, is that self-installation does not void the 5 year limited warranty. So if you know what you are doing you can save a few hundred bucks!
Other than that, there is not much new to say. We have the standard 80-140 °F temperature range (increments of 1 °F) which can be easily adjusted using the dial control. The system is self-modulating, meaning it uses no more energy than needed to meet you hot water demand. And we have an ETL listing, UL standard certification and a certification for lead-free compliance – this is about as safe as it gets.
Actually, there is one more thing: The Rheem RTEX-18 is the most stylish water heater in case that’s something you care about.
On a side note, another popular model is the RTEX-24. It’s a little bit bigger than the RTEX-18 and thus can supply more hot water in the same amount of time.
A few issues with leaks here and there and 2 or 3 systems that failed – nothing out of the usual.
We also read about problems with warranty claims.
The Rheem RTEX-18 works exactly as advertised, nothing more and nothing less. As long as you pay attention to the right sizing it’s unlikely that you will experience any problems. Taking into account the higher price tag, we rate it with 4 stars.
Let’s make this quick:
The Hyperikon 27 kW electric on-demand water heater stands out due to its low price tag. This does not mean, however, that it won’t provide plenty of hot water: 4 gallons per minute at a 46 °F temperature increase and 3 gpm at 52 °F increase.
You can’t go as high as 140 °F, though, like many of the other heaters allow. 126 °F is the maximum (minimum: 86 °F). A Celsius scale is also available.
What we don’t like? The instructions could do with an upgrade. Also, some of the parts are lower in quality which you kind of have to expect considering the price.
Another drawback is that the heater won’t activate at a flow rate lower than 0.85 gallons per minute. So not using enough warm water could cause the unit to remain inactive.
And lastly, the Hyperikon is not self-modulating as far as we can tell and uses more excess energy.
If you are on a tight budget the Hyperikon might be just what you are looking for. 3.5 stars.
Let’s continue this guide with a bunch of point-of-use (POU) water heaters, such as the Rheem RTEX-13.
Wait, Rheem RTEX-13? This sounds pretty familiar…
You are right! This is the smaller version of the RTEX-18 from before. So it comes with all the same features such as self-modulation to save energy and an intuitive control panel (read more above).
How much hot water are we talking about? About 1 to 1.5 gallons per minute, depending on feed water temperature, so not a whole lot but enough to shower without fluctuation.
It seems like there are slightly more issues with the newer version such as random leaking.
A single bathroom or kitchen sink, or a weekend cabin is what the Rheem RTEX-13 was designed for. Highly efficient, super small and stylish – 5 stars!
The EcoSmart ECO 11 is another familiar face. Again, it shares the same features as all models that are part of the EcoSmart ECO series (learn more here).
But since this is a POU heater, the hot water supply is significantly lower:
All in all, the EcoSmart ECO 11 is ideal for a single bathroom or sink and in cooler climates perfect for hand washing.
As mentioned before, rare issues include leaking or systems that just stopped producing hot water. Opinions about the EcoSmart customer service are mixed.
A tad more affordable than the Rheem RTEX-13 but at the same time a little less well received. 4.5 stars!
The ECOTOUCH is the cheapest point-of-use ETWH that runs on 240 volt.
5.5 kW are enough to heat 1.2 gallons from 67 °F to 109 °F. In other words: The unit is mainly for sinks, not for shower applications.
Alternatively, you can use the remote control to turn the system on/off and adjust water temperature.
Speaking of adjustment, the hot water heater adjusts power input based on flow rate and temperature settings in real time. When water flow is reduced, the system applies less power and vice versa. This allows for the most stable temperature management and optimal energy efficiency.
ETL safety approval and UL qualified for peace of mind? Check!
And the installation is very simple, too.
Our only concern is that the minimum required water flow for the unit to activate is 0.475 gallons per minute which is quite a lot when you consider that this is a point-of-use system. That means that the ECOTOUCH might not turn on (or turn off!) when you are not using enough hot water.
Keep in mind that the ECOTOUCH is for low-flow POU applications. We mention this because some users complained that they did not get very hot water which is not the system’s fault. All in all, solid performance and highly affordable. 4 stars!
Stiebel Eltron’s DHC 3-1 is our number 1 when it comes to point-of-use electric on-demand water heaters that run on 120 respectively 110 volt.
Bathroom or kitchen, this is a single sink unit, mind you. At 0.43-1.14 gpm flow, it won’t provide enough hot or warm water for showering.
This is also why the DHC 3-1 gets shipped with an aerator for pressure compensation that fits most faucets.
Anything else? Yes, the water heater is inexpensive, made in the USA according to German engineering, and includes a 7-year warranty against leakage and 3 years against defects in workmanship & materials through the manufacturer.
All safety standards are followed.
For one, the DHC 3-1 didn’t last very long for some users, between a few weeks and up to 10 months. At least the tech support is great.
Secondly, not everyone could get a steady stream of hot water, not even for a single sink. This might have to do with the minimum flow that is required for activating the heater (0.32 gpm).
And lastly, you can’t adjust output temperature. It’s controlled by input temp and flow rate alone which can be inconvenient.
Here we have a top rated 120-volt ETWH that is reasonably priced and works as advertised. 4 stars!
The US3 is part of the Bosch Tronic 3000C Pro heater series but is the only model that runs on 110/120 volt.
Apart from the fact that the unit is the most popular 120-volt water heater, there is not much to add.
Bosch Tronic 3000C Pros are compact and lightweight systems for point-of-use applications – the US3 supplies .5 gallons per minute at 41 °F temperature rise – such as kitchen sinks.
And they are backed by a 5-year limited warranty that covers the heat exchange tube(s) against leaking. All other parts are warranted for 1 year after original installation.
As with the Stiebel Eltron DHC 3-1, the main issue seems to be that in some cases this electric on-demand water heater simply stops working after a couple of months use. Usually, troubleshooting does not help.
Another problem is that the US3 is sensitive about water flow and shuts off if the flow rate drops below a certain threshold (0.5 gpm). This has to do with the built-in flow switch. As explained earlier, the result is that reducing water temperature at the faucet only slightly might result in getting no more warm water at all.
The system also does not allow you to regulate water temperature. It’s either on or off.
To be honest, we prefer the Stiebel Eltron DHC 3-1 over the Bosch Tronic 3000C Pro US3. The former has far fewer issues with systems that simply quit working for no apparent reason. Above that, it is less flow sensitive. As for the Bosch US3, our final verdict is 3 stars.
We will wrap things up by reviewing the two following electric tankless shower head water heaters:
Let’s start with the Dltsli that requires 240 volt.
What’s good is that the LCD touch display allows you to control output water temperature in 1-degree increments. It’s super simple to use.
In addition to the shower head, the package includes everything that’s needed:
The minimum required flow for the heater to activate is 0.3 gpm which is low, so that’s good.
As far as the GARLAT Boccherini is concerned, like we said it runs on 110 volt and offers 3 temperature settings: Cold, warm and hot. To adjust the water temperature in between these 3 stages, you have to increase/decrease the water flow.
A stainless steel hose and a dual shower head/handheld combo including installation accessories are part of the deal.
What we don’t like about the Dltsli is the overall low quality.
First of all, the flow control valve says “Temperature” and the scale is labeled with “Low” and “Hight” (no spelling mistake from us). Furthermore, the plastic valve is poorly constructed and prone to leaking.
Next, you can only set the temperature in Celsius, not Fahrenheit.
Speaking of temperature, don’t expect water that’s really hot, unless you reduce the flow by a large margin. On full flow which is 1.2 gallons the water is best described as lukewarm.
On top of that, the directions are badly written. And some customers received no instructions at all. Either doesn’t help if you want to access the hard-to-find power settings (there are 3).
The GARLAT Boccherini is the only ETWH on this page that has more negative reviews than positive ones at the time of writing this guide, and it’s obvious why: It does not work for too many users. Even the instructions are in another language for the most part.
These are not our favorite water heaters, although they are super affordable. We recommend you invest a bit more and buy one of the point-of-use water heaters reviewed further above, such as this one. Our verdict: 2 stars each.
More on ETWHs
In section 1, we reviewed the top rated electric tankless water heaters on the market. Next we are going to answer some of the most common questions our readers have about them.
As mentioned in the introduction, if you want truly instant warm or hot water whenever you open a tap you need a recirculation pump. To be more precise, you require a pump with a temperature sensor. What it does is measure the water temperature in the line where it sits – this can be near the heater or at a certain fixture – and pump the water back into the heater when a certain temp is fallen short of.
The water is re-heated and as a result, the time until you get hot water drops to a few seconds. Another benefit of recirculation is that almost no water goes to waste. But of course, a recirculation pump only makes sense if there is a long distance between the heater and the respective outlet(s).
Laing Recirculation Pump with Timer & Thermostat – Available on amazon.com
How can the water circle back? There are two options:
Pairing a recirculation pump with a tankless water heater requires a little more thought, though. This is because
If you have any questions about ETWHs please don’t hesitate to leave a comment below!
And don’t forget to come back to this page from time to time as we might find the next best electric tankless water heater.