On demand water heaters are one appliance that has been gaining quite a good popularity recently. This is due to its money saving advantage as its use of special technology allows saving quite a lot over the long term. Tankless water heaters are available in different types. Each offering its own advantages. The advantage of electric tankless water heaters is the most simplistic installation. It requires no venting or exhaust line, so it has more installation possibilities than the other types. You can place it in a small place where it would stay unobtrusive and not in the way. A common place to place them would be in a closet or even in the cabinet under the sink. They are suitable for both point-of-use applications and whole house water heating.
If you are on the market looking for the best electric tankless water heater in 2021, then the comparison chart and electric tankless water heater reviews below will help you choose the right model for your home’s water heating needs. This list of top 6 models was compiled based on research of the best options available in 2021.
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- Rheem RTE 9
- Water flow: 3 gpm
- Dimensions: 7.2 x 7.2 x 10
- Stiebel Eltron Tempra 20 Plus
- Water flow: 4 gpm
- Dimensions: 21.2 x 19.4 x 8.5
- Ecosmart ECO 18
- Water flow: 2.5 gpm
- Dimensions: 20 x 20 x 6.5
- SEISCO RA-28
- Water flow: 2.5 gpm
- Dimensions: -
- Stiebel Eltron DHC-E12
- Water flow: 1.5 gpm
- Dimensions: 4.1 x 7.9 x 14.2
- Bosch AE115
- Water flow: 2.6 gpm
- Dimensions: 4.2 x 15.2 x 15.5
- 1 Top 6 Electric Tankless Water Heaters
- 2 Ecosmart ECO 18 Electric Tankless Water Heater
- 3 Rheem RTE 9 Electric Tankless Water Heater
- 4 Stiebel Eltron Tempra 20 Plus
- 5 Seisco RA-28
- 6 Stiebel Eltron DHC-E12 E Series
- 7 Bosch AE115 PowerStar
- 8 Best Electric Tankless Water Heaters Comparison Chart
- 9 How Electric Tankless Water Heaters Work?
- 10 Efficiency
- 11 Traditional VS Electric Tankless Water Heaters
- 12 Electric Tankless Water Heaters Pros and Cons
- 13 A Complete Guide to Choosing the Best Tankless Electric Water Heater
- 14 Installing Electric Tankless Water Heater
- 15 Tankless Electric Water Heater Problems
- 16 Tankless Electric Water Heater FAQ
- 17 Conclusion
Top 6 Electric Tankless Water Heaters
Ecosmart ECO 18 Electric Tankless Water Heater
If you are looking for a whole house application model, the top rated electric tankless water heater is the Ecosmart ECO 18. It is suitable for your home if you have the incoming water temperature 62 degrees and above. To provide you with the best experience possible, the water heater uses the self-modulating technology. It works by adjusting the water temperature as per the set requirements. So you don’t need to worry about the temperature going up or down, the technology keeps it at a stable level.
This energy efficient model is capable of heating 2.5 gallons of water per minute, which should be enough to have one shower and one sink tap in use simultaneously. If you have showers with water saving shower heads, you can even use two showers simultaneously. With energy efficiency of 99.8%, it can be considered a green product.
The user-friendly features include a digital temperature control with which you can control the water temperature in 1-degree increments. The stylish and compact design of the unit is made from copper and stainless steel components. Though all the components are durable, in case something goes wrong you can easily replace them. If you are using this model for residential use, it also comes backed with a lifetime warranty. The minimal electrical requirement is 150 amp.
Rheem RTE 9 Electric Tankless Water Heater
On the other hand, if you are looking for a model with a point of use application, a good electric tankless water heater to buy is Rheem RTE 9. It’s also very compact and provides the users with continuous hot water on demand using the same power modulation technology. Depending on your water demand and the location of the points of use, the unit can also be used for two applications. There are a few great features that make this model one of the top options.
The durable brass/copper heat exchanger for durability. RTE 9 has a power rating of 9 kW and for the electrical connection requires a 40 amp breaker and an 8 AWG wire. The maximum power of this model is 38 amp. Like all Rheem models, RTE 9 is also installed without the T&P valve.
Depending on the incoming water temperature, the flow rate the RTE 9 provides is up to 3 gallons per minute. The minimum flow rate it can work with is 0.4 GPM, which is the rate that is required to activate the unit. RTE 9 is not recommended for use in colder climates. As for example, if you will need an 80-degree rise, you will only get 0.5 flow rate.
This water heater has a good response time, allowing you to have hot water much faster than with any gas tankless water heater. The easy to use controls allow to set the temperature from low to high. A LED light also shows if the unit is active or in standby mode. There’s also good warranty protection for this appliance. The heat exchanger is backed by a 10-year warranty, while other parts with a one year warranty.
Stiebel Eltron Tempra 20 Plus
This model comes from the most advanced Stiebel Eltron Tempra series. This series has upgraded both the design and technology. The improvements include heavy-duty electronics, advanced flow control, a hinged cover for easy access, and a single flow sensor design.
The Tempra 20 Plus is also suitable for whole house water heating if the incoming water temperature is above 60 degrees. So it’s more suitable for you if you live in the southern U.S. But can also be used in colder areas if your smaller unit is not working.
The digital temperature display features a convenient dial control, using which you can set the desired temperature anywhere between 86 and 140 degrees.
What makes this model one of the most energy efficient is the full power modulation which also includes a thermostatic temperature control. So this system works by calculating both water flow and incoming water temperature. Then based on this calculation adjusts the power required to heat the water to the required level. So while maintaining a stable temperature output, the unit uses as less power as possible.
The advanced flow control system also works to maintain the same temperature level, even if the hot water demand exceeds the unit’s capacity. It works by making automatic adjustments to the water flow.
The Tempra 20 Plus’ capacity is up to 3gpm, which it achieves with a 44-degree rise. The safety guard in this model protects it by not exceeding the water heating over 140 degrees.
To get it installed is very easy as it is done without any venting. The unit works with either 208 or 240 volts. Depending on the voltage used, the maximum amps will be either 80 amps for 240 volts or 70 amps for 208 volts. For the installation, it requires two 50 amps breakers and two 8 AWG copper wiring.
RA-28 is the most popular model from the Seisco brand. It’s also ideal for whole house application. It’s also suitable for commercial application. For example, if you have a restaurant or a salon. This model makes a powerful replacement for a conventional tank-type water heater, being able to support multiple hot water demands simultaneously. For the installation, the power requirement is minimum 150 amps.
It features lightweight modular construction and a very compact design for fitting it in tight places. The model can be used for both 208 V and 240 V. Seisco RA-80 is a four chamber unit. It features a power sharing distribution system. It works by providing an equal amount of heater to the water as it passes through the heating elements. The result is no temperature fluctuations, but an even level. The full power control works to maintain a stable water flow in order to conserve energy. So if your hot water demand goes down, the water heater will decrease the power level.
Seisco RA-28 also includes some essential safety features, such as dual low level detectors for preventing dry firing of the heating elements, self diagnostics, and a built-in leak detection and alarm.
With Seisco RA-28 you get more capacity as the highest water flow it can output is 4 GPM. Though with 4 GPM water flow, the temperature rise will be only 48 degrees. You can set the desired water temperature output anywhere between 90 and 130 degrees. For the installation, RA-38 requires 4 breakers with the size 30 amps each.
Stiebel Eltron DHC-E12 E Series
This compact package of an electric tankless water heater also provides over long term energy saving. The energy efficient technology it uses has the output of just 12 kW. This electric unit is ideal for bringing hot water to your sink or to one shower that has a water saving shower head.
It’s a 208/240 Volt electric tankless water heater with an output of 9,000 and 12,000 Watts accordingly. It’s a lower capacity heater, so it is suitable for application with lower temperature rise. On the front cover of the unit, there’s a small knob located that you can use as a dial to set the desired temperature. Stiebel Eltron DHC-E12 can heat the water to a temperature in the range between 86 and 125 degrees.
For the installation, you will need a 60 amp breaker and a 6 gauge copper wire. One more advantage of this system is the unique 3-year warranty for the parts of this electric tankless water heater.
Bosch AE115 PowerStar
The Bosch AE115 you can use as either a point-of-use unit or install it for the whole house application. It does provide the maximum output of only 2.6 GPM. It’s enough to run only one home appliance at a time. However, in some situations, it can provide enough hot water for two applications simultaneously. For example, you can use it to run two sinks at a time or to run two showers that have shower heads with low water flow rating. So if you have a busy household, with a very high hot water demand, this might not be the ideal option for you.
Bosch AE115 can either be placed on the floor or mounted on the wall. For the installation, the minimum electrical service to your home should be no less than 150 amps.
Best Electric Tankless Water Heaters Comparison Chart
|Product name||Water flow||Dimensions|
|Rheem RTE 9||3 gpm||7.2 x 7.2 x 10|
|Stiebel Eltron Tempra 20 Plus||4 gpm||21.2 x 19.4 x 8.5|
|Ecosmart ECO 18||2.5 gpm||20 x 20 x 6.5|
|SEISCO RA-28||2.5 gpm||-|
|Stiebel Eltron DHC-E12||1.5 gpm||4.1 x 7.9 x 14.2|
|Bosch AE115||2.6 gpm||4.2 x 15.2 x 15.5|
How Electric Tankless Water Heaters Work?
Electric tankless water heaters apply the same principle a conventional gas operated heater applies, only that they have a plug in socket for power and not a gas inlet. They also lack a tank and thus save as much energy that would have been used in standby mode as possible. A basic tankless water heater comes with a cold water line and an electric hookup. Other functions like expensive pipes, complicated designs and materials are extras.
Usually, there must be intricately designed coils that are either installed underneath the heater’s pipes or installed as part of the pipes that heat immediately the power switch is turned on. A great heater however only heats up the coils in the presence of water. If switched on while no water flows, you risk burning the piping elements. Also, many designs these days come with a microprocessor that ensures the ideal temperature levels are maintained.
A typical tankless electric water heater provides hot water at a rate of 2.5-7 gallons per minute, which unfortunately is often limited by the water consumption rate in a home. When the water demands are overstretched, even the most powerful coils are made inefficient, which is why you should think about buying an extra tankless water heater or buy a more powerful model. On the other hand, the simplicity of how a tankless electric water heater works makes them more reliable and more durable than any other models. Their parts can easily be replaced and overall maintenance costs are relatively low.
Traditional VS Electric Tankless Water Heaters
So, which one is better; a traditional water heater or a modern tankless electric water heater? Well, that’s your decision to make. However, we can highlight some differences between these two types of devices.
Traditional water heaters heat and store water in a 30-80 gallon tank. The preheated water is what you and your family use for showering, washing dishes and for other needs. When depleted, the water heater preheats water again and refills the tank. On the bright side, traditional water heaters are cheap and easily available. In addition, they are very easy to install. However, they consume a lot of power and don’t tend to last long.
Electric tankless water heaters, on the other hand, heats water as it passes through them; or what some people call heat water ‘on demand.’ There is no storage with an electric tankless water heater, therefore. You also don’t require spending on gas expenses. The greatest benefit with these tanks is that you get hot water throughout, plus they also consume far much less power. In addition, they save on storage space and could last for decades. Unfortunately, they are quite expensive, but sometimes they are worth every penny.
Electric Tankless Water Heaters Pros and Cons
On demand electric tankless water heaters have proven to be a good replacement for conventional tank type water heaters. Below you can learn the main benefits these systems offer, as well as the very few disadvantages they might have.
- An endless supply of hot water. One worry that instantaneous electric water heaters eliminate is running out of hot water. You won’t been worrying that someone showering before is going to use up all the hot water and leave none for you. So even if your family members take really long showers, you will still have enough hot water for yourself as well. Or if you are doing laundry, the endless supply allows washing load after load.
- Energy efficient. Electric on demand water heaters work on the same principle as all the other tankless water heating systems. It’s consuming power only when it needs to produce hot water, only when you turn on the tap. All the remaining time it’s just in standby mode. So these appliances have shown to result in up to 60 percent in savings on energy costs. As most of these models are rated over 99% efficient, you can expect some great savings on your monthly water heating costs.
- Environmentally friendly. As the electric simultaneous water heaters start using energy only when you require hot water, these units use less electricity and therefore cause less damage to the environment. Also, a lot of the modern models are manufactured from materials that can be recycled.
- Ease of installation. Electric type of tankless water heaters is probably the easiest to install. With just some basic plumbing and electrical skills, most users should be able to do it on their own. There’s no more complicated venting to do as with gas tankless water heaters.
- Space saving. These systems include no tank, so most of them have a very compact size. Due to their compact design, you can install into any spare place you have.
- There is only one con that is worth mentioning. Most whole house tankless water heaters don’t give such a high water flow. On many of the models, you will find the water flow is rated at only 2.5 GPM which would be enough to provide for one shower at a time. However, many people use these systems for point of use applications. So 2.5 GPM for one application is adequate.
A Complete Guide to Choosing the Best Tankless Electric Water Heater
A great tankless electric water heater could reduce your energy bills by up to 50%. When it comes to storage, you don’t have to worry about a tank taking up all your bathroom space, because these tanks are very small in size and take very little space in your house. They are also popular these days, but if you don’t know enough about them to make you buy one, read the following comprehensive guide for buying a tankless electric water heater.
Water Heater In Flow and Out Flow
Since there is no tank to store hot water, one of the main factors to consider here is the efficiency and volume of the water flowing in and out of the heater. You shouldn’t worry about capacity, therefore. Instead, consider the amount of hot water you use in your house on a daily basis or the frequency of using the showers and dish washers for instance. This is because most electric water heaters can only let out a certain amount of hot water per minute, and if the showers and dish washers take so much hot water in your home, you might consider going for a heater with the capacity to heat more amounts of water per minute.
Sizing an Electric Water Heater
In the absence of a tank, the only way to differentiate the size and power of a tankless water heater is by its flow rate. The water flow rate is measured in Gallons per Minute, but these can only be calculated once you know the device’s British Thermal Unit (BTU). The higher the BTU readings, the better the water flow rate. On average, a tankless water heater with a flow rate of 5.7GPM requires about 190,000 BTUs. There are however smaller sized tankless water heaters which deliver water at a speed of 1.2GPM. Such devices are probably only good for delivering water to single outlets, like one kitchen faucet or a single bathroom sink.
Energy Efficiency Ratings
Electric tankless water heaters can be ruthless power consumers. If you especially have a whole-house tankless electric water heater, be sure to only choose a model with the best energy efficiency ratings. Usually, the ratings range from 78-87%, and a device with the highest ratings means it converts more energy into heat at a faster rate.
Your Home Location
Tankless electric water heaters are some of the few home gadgets that are affected by ground temperatures. If you live in a generally cold location, or if you plan to install the device in a cold basement location, go for a water heater with a higher water flow rate. This is because, at the colder locations, the heater will have to raise its temperatures well above the ground temperatures to achieve a desired delivery rate.
Check out for Smart Functions
Go for a device with an oxygen depletion sensor or a fill wrap to shut off the device if it overheats. Also, check out for a warranty or any other smart feature you may deem helpful.
Installing Electric Tankless Water Heater
Select a location
Due to the small size of the tankless units, the location for the installation can be almost anywhere. It can be a small closet, under the sink, under stair storage area, or any other available space. However, when choosing the appropriate location, you should keep several points in mind which will in the future ensure safe operation and ease of accessibility to the unit.
Unless stated otherwise, most tankless water heaters are for indoor use only. For outdoor installation, it will need a suitable enclosure that will provide it protection from the rain, debris, sunlight, and insects. An important point to keep in mind is that the chosen location should not be subject to freezing temperatures. Frozen water inside the water heater can cause permanent damage to the unit, which will not be covered by the warranty.
Choosing the installation location, it’s recommended to choose one that is close to the application fixtures and to the main electrical panel. If you will install the unit very from the electrical panel, you will need a lot of wire to connect the water heater. Depending on how close the tankless electric water heater is to the hot water applications, the time it takes for the warmed up water to reach from the heater to your tap will vary. In most situations, that time is really fast. By installing the unit closer, you will make that time even shorter.
One more consideration is the ease of accessibility as you will need to do future servicing. Avoid choosing a location that will be difficult to access when you will need to perform maintenance of the unit.
Avoid also the following locations: next to combustible materials, underwater pipes, above electrical boxes or junctions, in a location with excess humidity, dust, or moisture.
Mount the unit
After choosing the location, the electric unit is ready to be mounted. If the model is designed for wall mounting, the back panel should have mounting brackets which using screws you should attach to the mounting surface. Make sure that the unit is even, then tighten the screws. Prior to mounting, make sure that the surface is solid and smooth.
Tankless Electric Water Heater Problems
If you are tired of spending hundreds of dollars on a water heater, maybe you should go tankless. But before then, electric tankless water heaters have some very concerning drawbacks which ironically not very many people give much attention. Read below to learn more
- Tankless electric water heaters are rather expensive, sometimes costing a thousand dollars more than conventional water heaters. And that is before you factor in installation costs, and especially the costs of changing your home’s wiring systems to suit the electric model. In some case, be prepared to spend in the upwards of $5000 on upgrading the electrical system in your home, and retrofitting your home with the help of professional plumbers.
- They don’t really save a lot of money to people living alone. In fact, expect to see your energy bills go up if you live alone and do spend a lot of water in the showers or with your dish washer.
- Electric tankless water heaters require regular descaling, and in most cases by a professional. And by the way, note that these devices are so new that it is not very easy to find a technician who can deal with them. On the contrary, you don’t require any technical maintenance costs on traditional water heaters, and if any, not as regular.
- They are not very effective in cold temperatures, yet- In very cold temperatures, these devices have to struggle to raise the minimum temperatures required to heat water, and ill often deliver hot water at a lower rate. Sometimes you might need to install more electric power if you live in cold climatic regions.
- They are not as easily available as other models-Okay, today tankless electric water heaters are more common than they were five years ago, but still, they are not very popular among consumers. Maybe it is because they are not as efficient as gas powered models are, or maybe it is because they are more expensive.
- They are easily affected by hard water- In the absence of a hard water softener, these water heaters get ruined fast.
- Tankless electric water heaters can get damaged if left unprotected in outdoor environments. It is better that you seal them tightly to prevent against water damage.
Tankless Electric Water Heater FAQ
- Can a tankless water heater be installed outdoors?
Yes, you can install a tankless electric water heater outdoor, albeit with a lot of care. Remember that its elements must be protected against freezing, rain or hot weather.
- Do electric tankless water heaters require Venting?No, Venting is mostly required if you heater also uses another fuel type, like gas.
- How to descale a Tankless water heater?To start with, understand that descaling varies depending on the softness of the water you use and on the quality of your water heater. All in all, here is how you can flush out built up scale;
- Disconnect the power source, close all service valves and caps
- Add a gallon of water into a bucket and add a quart of Flow aide
- Connect one side of a hose pump into the bucket and the other end onto the water heater’s cold valve
- Connect another hose pump into the hot valve and the other side into the bucket
- Plug the pump into ground receptacles and allow it to run for about 45 minutes
- Flush the heater for five minutes and reassemble everything back to normal
- Do tankless water heaters save money?Yes, they could save up to 50% in energy and maintenance costs.
Electric tankless water heaters are one of the most commonly chosen water heating systems due to their benefits. It’s advantageous for both your household and your savings as it uses much less energy if you compare them to traditional water heaters. These 6 best electric tankless water heater models were chosen as they are this year the most popular products on the market of this industry. The tankless electric water heater reviews were written on the basis of deep comparison and research of honest consumer feedback. So whether you are looking for a whole house electric tankless water heater or a point of use unit, We hope this guide has been helpful to you.