A hot shower is a great way to ward off winter blues and summer exhaustion. But water heaters are among the most expensive appliances in the average household. They can drive up your energy bills like no other, especially in the winters. If you are using a traditional tank water heater, now might be a good time to consider an upgrade.
Tankless electric water heaters have some proven advantages over their older counterparts, especially when it comes to driving down your energy bill. Should you upgrade? If so, which is the best tankless electric water heater out there at the moment? Check out our reviews and the short, but detailed buyers guide section at the end to find out the answers to these questions now!
Best Electric Tankless Water Heater Comparison Table
|Stiebel Eltron Tempra Plus 36 KW||Whole House||36||7.5||3 yr parts/7 yr leakage|
|EcoSmart ECO 36||Whole House||36||6||Lifetime|
|Atmor||Whole House||27||5||2 yr parts/7 yr leakage|
|Rheem RTEX 18||Small House||18||4||1 yr parts/5 yr heating chamber|
|Rheem RTEX-13 Residential||Small House||13||4||1 yr parts/5 yr heating chamber|
|Titan SCR2 N-120||Small House||11.8||4||1 yr electrical components/10 yr water components|
|Marey ECO 110||Small House||11||4||5 years|
|EEMAX HA008240||Point of Use||8||3||5 yr|
|Stiebel Eltron DHC-E 8/10||Point of Use||7.2 - 9.6||2.5||3 yr|
|Bosch||Point of Use||7.2||1.1||5 yr|
|SioGreen IR260 POU||Point of Use||6||3||2 yr|
|DLTSLI||Point of Use||5.5/4.5/3.5||1.2||n/a|
|Zinnor 8L||Point of Use||1.5||n/a||60 days|
Best Electric Tankless Water Heater Reviews
Stiebel Eltron Tempra Plus 36 KW – Most Powerful Model on the List
The 36 KW Tempra Plus is a massive tankless water heater from the German brand, ideally suited for large homes/families. Despite the massive output, this tankless water heater keeps a slim profile, with dimensions of approximately 15 x 17 x 5 inches. And it has the same simple grey design, with a detailed control panel with a colorful dial and LED display for temperature controls.
The best thing about the Tempra Plus 36 is its output flow which is more than any other unit we have reviewed so far. In cold weather (42 degrees water temperature), this unit is capable of consistently delivering nearly 4GPM of hot water. That is enough to run three fixtures simultaneously, like two showers and your kitchen sink for instance. And if you live in a warmer locale like Florida, expect that GPM to top out at 7.5, which can run four showers at the same time.
And yet you do not need to worry about creating structural changes to your home during installation, as this model does not need any venting system. The controls are also incredibly simple, which is another brilliant aspect of this heater. Stiebel has also included auto modulation in the Eltron Tempra range, which reduces unnecessary usage of electricity.
Stiebel is one of the more premium brands in the mix, and you will have to pay above market average for their heaters. And despite the premium pricing, some of the heaters in the Tempra range seem unable to handle hard or alkaline waters, with heating elements frequently encountering malfunctions.
EcoSmart ECO 36 – Most Powerful Tankless Water Heater from EcoSmart
With a 36 KW rating, this is the most powerful tankless water heater from EcoSmart. It has the same design as other water heaters in the Eco range, with a white exterior, large and colorful decals and a long black control panel with temperature control dial. The body of the heater measures roughly 17 x 19 x 3.8 inches, making it remarkably compact as well, despite all that power inside.
The most eye-catching feature on board this heater is its output capacity of 6 GPM in warm weather conditions. If you live in Florida or Texas, this water heater can power a bathtub or jacuzzi, or multiple showers and sinks simultaneously. Very few tankless water heaters have that kind of capacity. It also has self-modulated heating elements that reduce power consumption and provide efficient heating.
But the Eco 36 truly shows its worth further up north, in sub-40 degree cold water conditions. Very few tankless water heaters provide decent heating performance in the weather for one shower or one tap at a time. With a hot water outflow of 3.5 GPM in these cold conditions, the heater can run several hot showers simultaneously.
Such a powerful device poses its own set of challenges for installation and maintenance, as can be expected. You might need to upgrade the wiring of your home to be able to accommodate this device. EcoSmart does not provide a full unlimited warranty for their tankless water heaters, which can create inconveniences and additional expenses later down the line. If your local water quality is poor, the heater elements will probably malfunction much sooner as well.
EcoSmart Eco 27 – Best Electric Tankless Water Heater For Cold Climates
The Eco 27 is powerful tankless water heater from EcoSmart. The heater has a square shape, with a white stainless steel exterior. Measuring around 17x17x3 inches, it is still flat and compact when compared to a tank storage water heater. The exterior is white, with the bold branding of the company and a colorful logo of planet Earth in the shape of a droplet. On the side, there is the long vertical black control panel, with a small display and a temperature control dial.
The main advantage of the Eco 27 has to be its performance. Even in colder parts of the country where water temperature drops below 37 F, this unit is still capable of delivering hot water at the rate of 3GPM. That is enough water to run multiple taps or showers in a medium-sized home. In the warmer South, the output jumps to 6 gallons, which is more than enough for larger households.
Another great advantage is the temperature control settings. The dial is easy to use and can increase the temperature by increments of one degree. This device is capable of delivering water at temperatures between 80 to 140 degrees F. With self-modulating technology and three separate heating elements inside; the Eco 27 also saves on energy costs.
Despite the high performance, or maybe due to it, this unit does not last very long. And the limited lifetime warranty may not cover all the issues you experience with it. You might need to upgrade your home wiring as well, as this is a very power hungry unit.
Atmor 27kW/240V – Most Affordable Model for Whole House
This is the biggest tankless water heating unit from Atmor, with three heating coils inside a very industrial looking box. This device is a rectangular unit, measuring around 11x9x4 inches. The exterior is coated in dark metallic grey, with a small digital display unit and silver dial controller on the left. With minimal branding and small logos, the Atmor unit has a very understated look.
The powerful trio of heating elements ensures that you can get hot running water even in northern winters. This heater is capable of running a shower and sinks simultaneously, even if the water input temperature is under 40 F. The available temperature control range is also pretty impressive, at between 90-135 degrees. In warm weather down south, you could easily run a bathtub with this heater.
The digital display shows accurate temperature levels, and the dial makes it very easy to regulate the heat in one-degree increments. The body of the heater is very durable, made of stainless steel.
The heating performance is adequate, but the unit can take some time to get up and running. It also suffers from seemingly poor QC, as some parts malfunction.
Stiebel Eltron Tempra Plus 24 KW – Best Tankless Electric Water Heater For The Whole House
The Eltron Tempra Plus is an advanced tankless water heater from the famous German brand. At approximately 16x14x4 inches, it is a very compact device. The face of this rectangular box gets a very subdued treatment in grey. There is a light colored vertical control panel on the side, with a small digital display and simple knob controls. This is a made in Germany product.
The main advantage of the Stiebel is its tried and trusted German engineering and reliability. Also, this is a very powerful water heater, capable of running tap and shower simultaneously even in cold conditions (at 42 degrees F water temperature). The sleek design doesn’t take up much space and can fit snugly pretty much anywhere.
And it has a special design which does not need extra venting arrangements. That makes installation much easier. The digital temperature controls are easy to use and have a rich, colorful dial with a lot of useful information. The system has auto modulation and advanced flow control, which keeps energy use down while still guaranteeing constant temperatures.
The Stiebel is a high-quality device, and all that quality does come at a premium price. Yet it does not offer whole house performance, which is slightly disappointing. The heating elements are also vulnerable to high pH water and prone to frequent failures.
Rheem RTEX 18 – Stylish Residential Tankless Water Heater
Rheem heaters tend to have a very elegant look, and this whole house model doesn’t disappoint on that front. It has an upright rectangular shape, with silvery metallic exteriors and a petite black control panel in the top corner. Since this is a digital water heater, the control panel has an LED display and simple dial-based temperature controls.
The main advantage of this water heater armed with dual heating elements is the self-modulation. You don’t need both heating elements to keep burning all the time. Auto modulation saves electricity (and costs) by maintaining a flexible approach to heating water. It only uses both elements during peak demand.
The installation of the RTEX heater is very simple and straightforward. The capacity is not the highest out there, but it is still better than most. In warm weather, you can expect a peak output of 3 GPM, which is enough to run a shower and sink simultaneously. In the colder groundwater conditions up north, the output is reduced to 1.5 GPM, which is still enough to run a shower.
Though the RTEX 18 performs better than other weaker water heaters from the same brand we reviewed, its performance is still not up there with the best. It does suffer from fluctuating temperatures in cold weather conditions. Also, it may not provide enough hot water for larger shower heads.
Rheem RTEX-13 Residential – Best Electric Tankless Water Heater For Shower
The Rheem RTX 13 is a very classy looking tankless water heater indeed. It has a curved rectangular shape, with compact 9X4X13 inch dimensions. The exterior has a metallic rim, with silver shade inside. The control panel is dead center and small, with an LED display and a silver dial for temperature controls. The box has a very minimalist ethos, with a small Rheem logo on top.
The RTX 13 is a capable little heater that can easily power a single hot shower with minimum fuss. If you want a POU tankless heating system, this is worth a look. Thanks to its compact dimensions, it should work well even in small homes, cabins, or RVs.
It has self-modulating controls that help save power while delivering a consistent output. The twin elements are made from durable copper, which increases the longevity of this unit. The installation is also one of the easiest among all the products we reviewed. The digital display and dial controls offer a simple and streamlined user experience.
The performance of the RTX 13 is not the best, especially in colder temperatures. If you live in the northern US, this unit probably will disappoint with its feeble heating abilities. But if you live in tropical or warm weather areas like Hawaii, Texas or Florida, this might be a better fit. Also, the whole unit feels a tad overpriced.
The Titan N-120 is a very functional looking box, without any premium design elements. The metal box measures 10x12x5 inches, and has a white painted exterior, with a small control panel with push-button controls. It also has a digital temperature display. This unit is primarily intended to serve as a whole home heating system in warm weather locations.
The one thing we like about the Titan is that it is not a very pretentious product. Thew design is simple, industrial, and functional. They tell you upfront that this device will only work in warm weather, the kind you find in California or Florida. It can run 1-3 bathrooms, in optimal conditions.
The box is solidly built and looks very durable. It is also rather compact and should snugly fit even in cramped locations. This can probably do the work of a 40-gallon electric heater and deliver a lower energy bill as well.
Titan used to be a very reliable manufacturer in the past, but in recent years they seem to be having issues with Quality Control. Some units start malfunctioning within a few months. And the warranty also leaves a lot to be desired.
Marey Refurbished (ECO 110) – Inexpensive Model for Small Homes
The Eco 110 is a very sleek tankless water heater from Marey. It is a very compact device, ideal for use in small homes and cabins. The Eco 110 has a very minimalistic look, with a clean white exterior and simple control buttons and small LCD. The black teardrop shaped console is a nice and attractive touch on the white surface.
The main advantage of this refurbished device has got to be the bargain pricing. And you still get a five-year warranty on it from the manufacturer, which is comparable to what you get for a more expensive tank storage water heater. The controls on the digital panel and simple and very easy to use.
Measuring just around 11x7x3 inches in size, this is a very compact product. The wall hanging box can fit just about anywhere, which is a great aspect. And despite its petite size, the Eco 110 can still deliver 4GPM of hot water flow, which is enough to handle two separate fixtures. The Eco range from Marey uses special elements which are not affected by sediment build up due to hard water.
This particular product is not brand new. Though you get manufacturer warranty, it is less than what you would get from a new model in this category. The device is also not powerful enough to deliver water at a high enough temperature to two different outlets simultaneously. If you want optimum performance, you should only run one tap at a time. It may not work very well in cold climates.
The Eeemax offers something different on the color and design front, with a softly curved rectangular box unit. Shaded in powder blue or lilac coating, the box measures roughly 18x14x4 inches in size. This is more of a POU device, rather than a whole house heater.
The compact Eemax HA008240 is a decent choice for situations where you need a heater for a flow of 1.5GPM. This heater will work well with kitchen and bathroom sinks, as well as showers if you have low flow fittings installed. The box looks nice, and the knob-based controls are easy to use as well. In optimal conditions, it can increase your water temperature by 35 degrees.
The main issue with the Eemax is not so much its flaws as its limitations. This works best as a kitchen or bathroom sink attachment in southern weather. It cannot get the job done in cold northern conditions, with a max temperature rise of just 35 degrees.
The DHC-E 8/10 is a smaller, more affordable POU heater from the German brand Stiebel Eltron. The unit has a slim rectangular tower shape, measuring 8x14x4 inches approximately. The white colored box has a central control panel in stark black, with the trademark Stiebel dial controls and colorful labeling.
One noticeable advantage of this unit is the flexible voltage requirements. During installation, you can opt for either the standard 240V or the lower 207V option using a particular jumper. The device is well built and delivers excellent heating performance as advertised. It can reliably run a single shower with hot water.
The compact size means that it can be installed under your kitchen sink or in other cramped spaces in the house. You can easily install a couple of these in your home for different uses. The temperature adjustments are easy to make, and the labeling helps a lot as well.
The DHC-E 8/10 is not the most powerful tankless electric water heater out there. It can run a single shower, but that is its upper limit. You cannot run two fixtures simultaneously with this water heater. And it might struggle in cold winters as well.
Bosch 7.2 KW – Best Small Tankless Electric Water Heater
Bosch is probably the most famous name on this shortlist. And this a very compact POU water heater from their range of tankless water heaters. The design is very minimalist, with a plain white rectangular body measuring around 6x13x3 inches. That makes it an ultra-compact unit.
The Bosch is a very straightforward product. It will raise the temperature of your water by 35 degrees F and sent it out at a constant flow rate of 1.1 GPM. This unit works well under your kitchen or bathroom sink, where it will sit unobtrusively.
The design is very clean, and it does not have any controls because there is nothing to control! It starts automatically and shuts down automatically as well. This is a great option for home as well as office use. In its 120V variant, it is also perfect for boats and RVs. It also has an Energy Star rating.
There are very few drawbacks for such a minimalist and limited device. The only thing we could identify were minor quirks that seemed to prop up after regular use. This seemed to indicate a lack of quality control from Bosch.
The IR260 is one of the smaller POU devices we have ever tested. Measuring just 13.5x8x3 inches approximately, this compact device seems perfect for a small cabin, RV, or your home kitchen sink. And it also has a very minimalist design, with a white rectangular face, with simple three button controls (power, high and low temperature) at the bottom.
The IR260 is a great option to hook up to your kitchen or bathroom sink. It offers enough heating performance for this kind of use. With low flow fittings, you might even be able to get a shower to function using this unit. But the main feature is the advanced quartz heating element used in this heater. It doesn’t get affected by hard pH water, which can be a serious issue for copper heating elements.
Its diminutive size means that you really cannot use this device for anything more than washing hands at the sink. The 30 Amp rated IR260 is simply not big enough to run a full-sized shower on its own. The heating performance is also rather underwhelming.
DLTSLI – Compact and Affordable
Though they call it a water heater ideal for both bathroom and kitchen, the DLTSI looks made for one purpose mainly. It comes with an attached shower head which would look very much out of place in a kitchen! The body is a tall rectangular tower design, made of white ABS plastic. The unit measures around 12x5x3 inches and is one of the most compact tankless water heaters out there.
The max temperature limit of this unit is about 120 degrees F, which is pretty decent for such a small device. It looks very clean and well put together. The inclusion of a shower head is a great feature. The water does not have to travel very long from the heating element to reach the shower. The device is also very affordably priced, which has to be its strongest suit as well.
Despite the inclusion of a shower head, this heater cannot deliver a proper hot shower in all weather conditions. It can heat up the water but at the cost of a very low flow level. The plastic body is also not the best option in this category.
Zinnor 8L – Low Power Model
The Zinnor is made from white plastic with metal bits and has a very clean shape and design. The control panel with temperature control knob is situated at the bottom of this rectangular box unit. The unit is pretty thick, at 10x10x1 inches approximately.
The one redeeming quality of the Zinnor 8L is its cheap and affordable pricing. The water heater also has a very pleasing design. It might be useful as a backup option to complement an existing heater in your home. Or it could be used in other areas like a garden shed.
The product seems like a cheap, Chinese manufactured item, with a lot of noticeable issues. The plastic build quality is a concern. It also has severe Quality Control issues, and does not seem to function properly in many instances. The heating action is also underwhelming, to say the least.
Best Electric Tankless Water Heater Buyers Guide & FAQs
What are tankless water heaters?
You probably have a storage tanker water heater at home. These are easy to understand. They collect water from your pipes in a dedicated tank. The heating element inside the tank creates hot water for your taps and showers. Simple and straight to the point.
Tankless water heaters take an altogether different approach to heating water. Instead of collecting water in a storage tank and continuously running to keep it hot, these heaters work on the “on-demand” principle. They use powerful heat exchangers to raise the temperature of water very quickly.
This means that these devices can supply hot water on demand when you turn on the tap. They do not need to store the hot water in a large tank, hence the name tankless water heaters. They are also called on-demand water heaters.
They have been around for a long time in parts of the world like Europe and Japan. But it is only recently that these water heaters have been making inroads here in America. The green movement is partially responsible for the increased interest in these heaters, as they are more environment-friendly than old-school water heaters.
How do tankless electric water heaters work?
In a storage tank water heater, the water stored in the tank is kept hot continuously. The storage tanks have a capacity of anywhere from 20-120 gallons. When you turn on the hot water tap/shower, this water is delivered to you through pipes. But in tankless water heaters, the cold water from the mains is not stored in a tank for heating.
Instead, the device starts working when the water is brought to the heat exchanger inside the water heater. When you turn on the tap, the cold water is sent to the heater via the inlet pipes. This water is quickly heated up and sent through the pipes to your tap or shower head. As long as you keep the tap open, the hot water is supplied continuously.
The capacity of a tankless water heater is calculated in gallons per minute or GPM. Typically, you can expect such heaters to deliver between 2-5 gallons of hot water per minute. When the tap is closed, the device also stops working.
How does tankless electric water become more energy efficient?
For starters, an electric water heater does not use any gas to heat up your water. That in itself is a huge factor, as it can help slash your gas bills by a considerable margin if you are using a gas water heater. Gas powered heaters are less efficient, as it is not as easy to start and stop heating an element using gas (in contrast to electricity).
Beyond the gas costs, a tankless electric water heater has some significant efficiency advantages over all storage tank water heaters. In the traditional heaters, there is a concept called standby heat loss. Those heaters are constantly working to keep the water in the tanks hot. And inside the storage tank, that hot water is constantly losing heat energy. Even insulated storage tanks suffer from this kind of inefficiency.
Tankless water heaters circumvent this kind of inefficiency with an on-demand supply model. Department of Energy estimates indicates that electric variants are 99% efficient, compared to traditional electric heaters which are 93% efficient.
What are some pros and cons of tankless water heaters?
- They do not run out of hot water.
- They are more energy efficient, as there is no standby heat loss.
- They last longer than traditional water heaters.
- They are more compact and space saving than ordinary storage water heaters.
- They can reduce your energy bills.
- Some models can be operated by remote.
- Electric variants do not produce any greenhouse gases.
- Initial costs are much higher when compared to storage tank water heaters.
- You might have to install extra wiring and vents for a new tankless water heater.
- They might increase electricity bills slightly.
- The output is restricted by the flow rate and temperature of water in your pipes.
- Some water can be wasted in the initial moments when you turn on the device.
Are there different kinds of tankless water heaters?
Yes indeed, there are several different types of tankless water heaters available in the market. The main differences relate to the type of energy source used, and the size and location of the water heater.
Point of Use (POU) Vs. Entire Home Systems
POU systems are installed closer to the output plumbing fixture and serve just one tap or shower. These tend to be smaller electric tankless water heaters. POU systems can be installed underneath your kitchen sink or inside your shower. As the name suggests, an entire home system is larger and installed in a central location. It is designed to handle all the hot water applications in your home.
Smaller POU units are more efficient as they are located closer to the tap or shower. So the hot water has to travel a shorter distance, which means that less heat is lost in transit. But with a central system, the water has to travel a longer distance to reach some fixtures, and you might end up getting less warm water in some pipes.
POU systems are ideal as a supplement to an existing tank water heater. You can use these on specific fixtures to reduce the load on your existing water heater. But if you want to provide hot water to your entire home using these, you will have to buy multiple POU systems. Entire home systems function more as an out and out replacement for your main tank water heater.
What is the deal with Energy Star Certification and Federal Government rebates?
Tankless water heaters come with some considerable positive effects on the environment due to their higher energy efficiency when compared to traditional heaters. The Energy Star label is a government-backed standard for improving energy efficiency. It was formed to encourage efficient use of energy, reduction of greenhouse gases, and to help consumers pick products that achieve these aims.
Currently, this rating is only available for gas powered tankless water heaters as they offer more energy efficiency and savings than old gas-powered heaters. Electric tankless heaters are also more efficient than electric storage tank heaters, but the difference does not qualify for an Energy Star rating.
The same also applies for Federal Government rebates, which apply to new purchase of gas-powered tankless water heaters. This was established to encourage consumers to buy these gas-saving devices despite their high cost. Electric heaters do not need this system, as they are very affordable already.
What is the relationship between flow rate, water temperature and output of tankless electric water heaters?
These water heaters work on-demand, meaning they only switch on when the input water flow rate pressure reaches a set limit. This happens whenever you turn on the tap or shower, or connected water fixture.
In a storage tank system, the elements have more time to heat up the water. But this luxury is absent in the case of tankless water heaters.So, the heating capacity of the element inside these heaters depends on the initial temperature of the water.
For example, if you live down south in Florida or Texas, you can expect the heater to deliver more hot water per minute, and at a higher temperature as well. In the colder northern states like Vermont or Montana, the same heater will deliver less water at the same temperature, due to the colder input water.
Tankless electric water heaters are a varied bunch. There are some European imports as well as Chinese and US made products in our list. They range in price fro, just over 100 bucks to close to 1 grand. There is also wide variation in performance levels, with some working only in warm weather. But we have tried to create an all-inclusive list highlighting all these diverse products and user niches. Hope you found this review useful. Thanks for visiting!