Best Electric Tankless Water Heater Reviews 2020

Electric tankless water heaters (also known as “electric on demand water heaters”) consistently provide hot water on demand without needing to preheat a tank of water as you would with a traditional storage heater. The benefit of this is that you don’t need to wait for hot water if someone has been hogging the shower all the day!

When hot water is in demand, for example if you were to turn your hot tap on, the water enters the hot water heater directly from your main water supply. It is then quickly heated up by a heating element. Gas tankless water heaters on the other hand, use a burner instead of a heating element.

If you have a storage heater and you find you are getting no hot water, or if you are just in the market looking for an upgrade, you’ll find valuable information about water heaters, including Rheem water heater reviews and some electric tankless water heater installation help in this expert guide.

Quick Picks: Best Tankless Electric Water Heaters

Stiebel Eltron Tempra Plus
  • Flow: 0.77gpm
  • Fixtures: Up to 6
  • Watts: 12 – 36kW
  • Volts: 240V
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Rheem RTEX-24
  • Flow: 5.9gpm
  • Fixtures: Up to 2
  • Watts: 24kW
  • Volts: 240V
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Ecosmart ECO 36
  • Flow: 6gpm
  • Fixtures: Up to 3
  • Watts: 36kW
  • Volts: 240V
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Marey ECO150
  • Flow: 5gpm
  • Fixtures: Up to 2
  • Watts: 14.6kW
  • Volts: 240V
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The first tankless water heater to mention is the Stiebel Eltron Plus range which gives you all you need from a water heater at a fair price.

These water heaters are of a robust and high quality construction with a sleek, almost flat design so they can pretty much fit anywhere!

You can choose which of the models in the range is suited for you based on the location you live and the amount of simultaneous hot water fixtures are likely to be used at once.  

The range starts with the Tempra 12 Plus which can only run on 0.37 gpm flow rate and operate one faucet at a time. It ends with the Tempra 36 plus with a 0.77 gpm flow rate and the ability to operate up to 5 or six simultaneous hot water fixtures!

The control panel is extremely easy to use allowing you to set the temperature of the water and also limit the usage to certain activities. It runs completely silents too so this heater won’t disturb you when it’s in use.

Stiebel has their own advanced internal flow regulation technology built in too, so even if the hot water is in a higher demand than your model can handle, instead of the water going cold for one fixture, the flow will be reduced. This is a far sight better than getting a shot of cold water while in the shower!

Being an tankless hot water heater there is no need to vent it as you would a gas water heater, as there is no carbon monoxide output. This makes installation costs a little cheaper for you and with a water heater as proficient as this, it’s very much worth the asking price. 

The anticipated Rheem water heater review does have to start out by pointing out that Rheem is an excellent brand who are widely trusted to provide reliable and high performing heaters.

Their electric tankless water heater is no different and is constructed with the same high quality as their other products. 

This particular model is easy to install and compact enough to fit in any room or storage closet.

It’s not as powerful as the Stiebel Eltron Tempra 36 Plus with a flow rate of up to 5.9gpm and is only really suited for smaller households as it can’t run on more than two hot water fixtures at once. Sometimes even two is a struggle for this heater.

Having said that, it’s perfect for a small household as it provides hot water extremely fast and will continue for as long as you need it. The heat owes its ability to respond quickly to the three heating element set up it has allowing for cold water to warm up in no time at all.

The user interface is extremely simple, allowing you to simply turn a dial to change the output temperature of the water. It has an LED screen to display the temperature you have chosen which is large, clear and easy to read.

The Ecosmart range of hot water heaters are brilliant for those who live in the colder states as it has its own self regulatory technology.

It allows it to heat water up to the desired temperature quickly. Even if the water input is as low as 37 degrees Fahrenheit!

It’s somewhat more powerful than the Rheem RTEX-24 and for small households it provides ample hot water for up to 3 hot water fixtures and can even handle more.

It even has the capacity to run a jacuzzi!

Also similar to the Rheem tankless water heater it has a simple interface with an easy to use dial that allows you to adjust the temperature. Your desired temperature is displayed on a bright and clear LED screen.

If you only have a small household or are living alone, you could save yourself a lot of money by having the Marey ECO150.

It’s a small and compact water heater with a low capacity for delivering hot water. However, it is inexpensive and suitable for those on a budget.

It’s powerful enough to operate two hot water fixtures at a time, but doesn’t perform like the best electric tankless water heater. 

When two hot water fixtures are active it can only heat them up to 41 degrees Fahrenheit and this is at a flow rate of 2.5gpm.

A positive side of this water heater is its high quality stainless steel water channel that is corrosion resistant and prevents the build up of chlorine or calcium which serves to extend the lifespan of the water heater.

Benefits of an Electric Tankless Water Heater

You may be wondering if these water heaters are worth it, and the answer is a confident yes! There are many benefits to having a tankless water heater, beginning with their energy-efficiency and ending with saving you money on a month to month basis. 

Let’s take a look at the advantages of having an electric tankless water heater when compared to storage heaters:

Electric Tankless Water Heater vs Storage Tank Water Heater


In the case of water heaters, efficiency is a measurement of how much energy is spent transfering heat from one medium (fuel source) to another (cold water). It takes into account energy loss which is why tankless water heaters in general are considered a to have a higher efficiency (at 80% on average) than storage tank heaters.

The reason is tank heaters suffer from standby heat loss which occurs because the water in the tank isn’t heated throughout the day in an effort to save energy. The tank may already be hot, but will lose heat as time goes on and will need to heat the whole tank again.

According to; if your home uses less than 41-gallons of hot water daily, tankless water heaters are 24-34% more efficient. This efficiency increases by 8 -14% for homes that use around 86-gallons of hot water per day.

On-Demand Hot Water

As mentioned earlier in the article, the main benefit of having a tankless water heater is being able to get hot water whenever you want it without having to wait for the heater to warm up a storage tank of water.

Storage tank heaters can at times struggle to meet the hot water demands of large families, even if everybody is having a quick shower in the morning before work or school. The last one to get into the bathroom may find that there’s no hot water left for them. There’s a few choices in this situation, first you can upgrade the size of storage tank water heater you have in your home. A second option is to switch to a whole house tankless water heater. A third option would be to consider installing a 

Given all the other benefits of having a tankless water heater, it is certainly the smart choice.

Space Saving

Without the big, bulkty tank attached to it, and all the mechanical workings of a gas tankless water heater; an electric tankless water heater is the ultimate compact water heating method for a home.

They are really easy to fit in closets and on walls giving you much more storage space for other things. They’re the best option for those who would like to have a dedicated water heater for a particular room because its super easy to fit a small electric tankless water heater into the bathroom just to be used for the hot water faucets in there.

They are really easy to fit in closets and on walls giving you much more storage space in your closets, basements and rooms.


They’re the best option for those who would like to have a dedicated water heater for a particular room because its super easy to fit a small electric tankless water heater into the bathroom just to be used for the hot water faucets in there.

Need help with a repair or install? Get a free estimate online from top local home service pros in your area.

Not Instantaneous

Tankless water heaters do not provide you with hot water on demand the very instant that you run the hot tap, this is a misconception. The water is heated on demand but then it has to travel through the pipes to the faucet that has requested it.

This doesn’t mean that it takes a long time to get your hot water but it can be longer depending on how far away your faucet is from the heater combined with the ignition start up sequence, that’s why electric tankless water heaters are quicker.

Storage heaters on the other hand, already have the water preheated and so will deliver water to your chosen faucet quicker. But when the tank runs out on a storage heater you will be waiting for even longer for hot water while the tank is reheated. So there is a trade-off.

With that being said, that does depend on how good the water heater you buy is. As we mentioned earlier, the internal components of the water heater determine is lifespan and also its performance, with higher qualities being better able to provide hot water at faster rates.

Those with in-built recirculation capabilities are even more proficient and able to deliver hot water faster to the degree where it would be pretty much instantaneous.

Electric Tankless Water Heater vs Gas Tankless Water Heater


A great advantage that electric tankless water heaters have over gas is that they do not require any ventilation and they have no carbon monoxide risk. This means that installation costs can be a little cheaper too as the technician isn’t having to deal with fitting flue pipes through walls.

Running Costs

Natural gas is generally a cheaper fuel than electricity and because of this, electric tankless water heaters do cost more to run on a daily basis than gas. Exactly how much depends on the price for utility fuels in your state.


Electric tankless water heaters are more reliable than gas as they have a lower number of parts which experience damage just from over time use, such as the pilot light. As a result, electric water heaters last longer before needing to be serviced.

Power Outages

Gas tankless water heaters may be a better choice if you are prone to experiences power outages for whatever reason. The pilot light and combustion of gas is independent of the electrical system and so will work during an outage.

Energy Efficiency

We have already mentioned the standby energy loss that occurs in storage heaters. Well, you save energy with an electric tankless water heater because it does not experience this issue.

Gas tankless water heaters also do not suffer from standby energy loss but they do have a constantly running pilot light which costs as much energy as what is loss through standby energy loss and so in that respect they can be less efficient than an electric one.

Tankless Water Heaters in Cold Climates

A common concern for electric tankless water heaters is whether or not they work well in cold climates. The truth is they do not generally perform as well in colder climates than their gas counterparts.

In towns and cities that happen to be situated in a state with a particularly cold climate, the water supply temperature would naturally be lower. This in effect requires more work from the water heater to heat it up, in effect extended the time it takes for you to get your hot water.

However, this is only true when a low quality water heater is used, as high quality water heaters with a better build and as mentioned earlier: internal recirculation capabilities would be able to deliver hot water quicker no matter the temperature of the cold water input.

Need help with a repair or install? Get a free estimate online from top local home service pros in your area.

Downsides of an Electric Tankless Water Heater

There’s not many things in this world that comes without drawbacks:

The cost of purchasing and installing a tankless water heater can be a little more expensive than a storage heater.


With that being said, you will save money on the energy bills and will most likely make up the expense within a few years. Given the longer lifespan that tankless water heaters have over storage heaters, you’ll have up to 30 years to make back the difference!

Tankless water heaters have a lower gpm (gallons per minute) capacity than storage heaters and so are usually not powerful enough to provide hot water for multiple uses at a time. This is not usually a problem for small or medium households, but for homes with many family members and guests it could be a problem.

You may be wondering what a cold water sandwich is, it does sound weird doesn’t it? Some of you will already know and it does make sense when you hear what a cold water sandwich is.


A cold water sandwich is when water temperature fluctuate dramatically for a moment. The water can be nice and hot and then suddenly you get a burst of freezing cold and then it returns to hot again.


This is an unfortunate common occurrence in tankless water heaters, particularly gas ones, and it happens when the hot water turned on and off and then on again in quick succession.


It’s because every time the hot water is requested, the ignition sequence has take up to 10 seconds to begin heating the water and when the hot water is turned off and then on again, the ignition sequence restarts.


A way to avoid this is to ensure you aren’t turning the hot tap on and off frequently, and if you had no choice but to do that, be aware that you may get a shot of cold water. It’s quite a nasty experience when in the shower but otherwise, it shouldn’t pose too much of an issue.

What Size Electric Tankless Water Heater Do You Need?

While gallon capacity, recovery rate, and first-hour rating are used when selecting traditional storage water heaters, tankless water heaters are chosen based on flow rate, otherwise known as water capacity.

Therefore, when selecting a tankless hot water heater for your family disregard the capacity of the unit and instead think about the flow rate. Other important values given to tankless units, which are important when determining flow rate include BTU (British Thermal Unit) input and efficiency ratings.

It’s also important to note that although tankless units don’t run out of hot water like storage units, they may not heat water fast enough to meet all of your demands. This is why it’s important to think about your hot water use when you are making a decision based on size.

BTU value – This value is used to determine the temperature increase per 1 pound of water by 1 degree. Therefore, the higher the BTU value, the greater the flow rate. Typically, 190,000 BTUs are required to provide 5.7 GPM of water.

Flow rate/Water Capacity – This is given in gallons per minute (GPM), which hinges on a given heat increase and typically falls into the 4 gallons to 10 gallons per minute categories. For example, a unit capable of supplying enough water for 3 water demands at once i.e. a single faucet and two showers is typically between 6 and 10 GPM.

Efficiency – The efficiency rating is important to consider if you want to make substantial energy savings, which in the long term will help save you money.

Efficiency is a metric of heat transfer from the fuel source to the hot water. The great thing is that today you can easily attain a tankless water heater with 90% and above efficiency rating.

Electric Tankless Water Heater Installation

If you consider yourself particularly handy around the home or even if you are a contractor, you maybe able to save some money and handle your tankless water heater installation yourself.

It’s important that if you are considering doing this, pay attention to state regulations regarding this type of installation and contact your local authority on obtaining a permit and water heater installation codes.

You will need to refer to the manufacturer’s instructions because different models have different installation requirements regarding the type of electric cables and breakers that are used. Most models don’t need a water heater hose and supply a pressure fitting install the heater right onto the water pipe.

After installation but before powering the heater on it’s wise to flush your home water system of any air bubbles by turning the main water supply off and opening the faucets. After this, turn the main water supply back on and then power the water heater.

2 Pole Circuit Breaker

Need help with a repair or install? Get a free estimate online from top local home service pros in your area.

If you are unable to perform the installation yourself or if you are wise enough to know you are not quite skilled enough to do so, it’s always best to get a contractor to get the job done to a professional level.

If it’s installed and maintained properly, it will be more optimized for your home, increasing its energy efficiency and your savings on utility bills over the long term. A professional HVAC technician would be taking into account multiple factors when doing an installation including your local climate, the building requirements and safety.

About the Author

Dave Miller is a HVAC technician with over 10 years in the industry. Dave created HeatTalk with the ambition for it to become a resource for individuals looking for answers, whether they be a layman, student or a professional.