Best Tankless Water Heater Reviews of 2019

If you’re looking for a swift and efficient system that will deliver warm water into your home, then you’ll be wanting a best tankless water heater. These nifty little things are much smaller than a storage water heater, more reliable and long-lasting, and much more efficient.

If you’re in need of one, then you’re in the right place – stick around as we unveil top ten best water heater contestants (and teach you a little bit about them too) on the market.

Top Ten Best Tankless Water Heater






3.0 GPM


Takagi T-KJr2-IN-ING

6.6 GPM


Takagi TH-H3-DV-N

Editors' Choice

10.0 GPM


Rheem RTE 13

4.0 GPM


Stiebel Eltron Tempra 24 Plus

Refer to customer

support for size

and capacity.


Takagi T-KJr2-IN-LP

6.6 GPM


Eccotemp Systems L5 Portable

1.4 GPM


Stiebel Eltron Tempra 29 Plus

Refer to customer

support for size

and capacity.


EcoSmart ECO 18

2.5 GPM


EcoSmart ECO 36

Editors' Choice

3.5/6.6 GPM


Last update on 2020-03-19 at 19:48 / Affiliate links / Images from Amazon Product Advertising API / Amazon Disclosure

Best Tankless Water Heater for The Money Reviews

Gas Heaters vs. Electric Heaters


Starting with gas heaters, this type of device is generally more powerful. Gas heaters usually have a much better flow capacity, and are able to heat up the water faster and in larger quantities. These heaters are able to deliver hot water almost immediately, no matter the distance between the heater and the place where hot water is being used.

However, gas is more expensive. For every bit of power you squeeze out of a gas heater, your gas bill will go up. Conversely, these devices have been built for maximum efficiency, and they will try to reduce your gas bill, and some of them will reduce it quite significantly. Some of the like products above have been known to reduce gas bills by as much as $50. Even so, the gas is much pricier than electricity.

That being said, it becomes obvious what is the main strength of electric heaters. They are extremely effective, especially if fitted with self-modulation technology, as is the case with EcoSmart ECO series of heaters. These heaters are rated to be 99.8% energy efficient, and they reduce electricity consumption by 50%, effectively saving you money on the electric bill.

However, it also becomes clear where they lag behind the gas heaters. They usually produce much less energy, and their capacity is less than their gas counterparts. With an electric heater, you will be able to run but a few appliances and maybe 2 showers at the same time. Usually, they are rated to 4-6 gallons per minute, while gas heaters produce about 6-10 gallons of hot water per minute.

On other note, electric heaters are long-term investments. They are usually much pricier to install, which they compensate by reducing the electricity bill. As is the case with Stiebel Eltron heaters, they require you to call both the plumber and the electrician.

Best Electric Tankless Water Heater

EcoSmart ECO 36 Electric - The Best Tankless Water Heater for Your Money - Editors' Choice

And at last, we come to the end of our list. The last item we have for you is the ECO 36, another member of the EcoSmart ECO family. This product is much the same as the ECO 24, in the sense it has also been built to handle lower water temperatures. The system is able to handle water temperature of about 37 degrees, making it perfect for the northern part of the States and Canada.

Like the other heaters in this series, ECO 36 features the self-modulating technology. Like we explained, the system is capable of introducing just as much energy as it needs to warm up the water to the desired temperatures, without using excess energy, conserving as much of it in the process. The system is rated to be 99.8% energy efficient, just like the others.

As for the capacity, this system is quite good. In the colder climate and colder weather in general, the heater can deliver about 3.5 gallons of hot water. However, in warmer climates and when working with warmer water, the system is able to deliver a very decent 6 gallons of water per minute.


  • Small and compact design meant to take as little space as possible.
  • The system is very efficient, saving 50% more energy.
  • Works well with very cold water.


  • The system needs 150 amps dedicated to run properly.
  • The system, as you can see, has a much lower flow capacity in colder weather.
  • Professional installation needed for a warranty to cover the product.

EcoSmart ECO 27 Electric Tankless Water Heater

If you’re living in the northern States, or Canada, then your best bet for a healthy supply of hot water is this outstanding EcoSmart ECO 27 water heater. As a member of the ECO series, this water heater poses excellent characteristics and is rated to very high volume. But the reason we recommended it for those living in northern States and Canada is because it is optimized for cold weather.

Not all heaters work in cold weather well. Not all of them can heat up very cold water, giving you a solid stream of lukewarm water instead. However, ECO 27 is capable of working with water which temperature is as low as 37 degrees Fahrenheit. Such low water temperature can cause damage to the heater itself, or make it overexert itself, again ramping up the electric bill.

ECO 27 has a smart sensor that reads the temperature and then calculates just how much energy it needs to heat the water. It also has a digital display where you can set the water temperatures yourself. The heater is rated to be able to heat a large amount of water quickly, such as that you can turn on four showers and a dishwasher, and you will still be getting searing hot water.


  • Able to operate at extremely low temperatures.
  • Able to heat water which temperature is as low as 37F, and not sustain damage.
  • The heater has a very high volume rating, and is able to heat up enough water for four showers and a dishwasher simultaneously.


  • The device is rated to very high amperage, so make sure how much can your circuit stand, so as not to overload it.
  • The warranty on the heater is only valid if you install it with professional help.
  • The heater is prone to cold water sandwich effect.

Rheem RTE 13 Electric Tankless Water Heater

Coming up next, we have the Rheem RTE 13 Electric Tankless Water Heater. For those wanting a more point-of-use type heater, this is a very reasonable choice. The heater is small and compact, very sturdy and reliable, and, most importantly, very affordable. Overall, this is one of the least expensive items on our list.

Rheem RTE 12 is a very simple device to use and install. It comes with a standard 1/2’’ water connection. The unit has a simple temperature control, coupled with LED lights that indicate active elements, and a standby mode. You can set the temperature of the water yourself. The unit uses a rugged brass/copper heat exchanger for reasons of reliability and efficiency. The heater is very efficient when it comes to electricity expenditure, and will have a positive effect on your electric bill.

As for the flow capacity this unit delivers, it isn’t half bad. It’s still weaker than the Takagi heaters, but electric heaters tend to be less powerful overall. Rheem RTE 13 can deliver a total of 4 gallons per minute, limiting its use to about one shower. Best electric water heater? It just might be!


  • A very compact and small device, easy to install and operate.
  • The device is quite inexpensive
  • The device is very efficient, and is guaranteed to reduce your power consumption.


  • The unit is limited to 4 gallons per minute flow, which will be enough for a single shower.
  • While the device can be installed by you, you ought to live it to the professionals, as the warranty only covers a device that has been installed professionally.
  • The device is perhaps ill-suited for use in colder climates.

Stiebel Eltron Tempra 24 Plus Electric Tankless Water Heater

We always say that German products are the best products. When it comes to machines, the Germans are above else in ingenuity and craftsmanship. This is also true for the Stiebel Eltron Tempra 24 Plus Electric Water Heater.

This heater is one of the most efficient heaters on our list. The good thing is that you can choose the size of the unit, and attune it to the needs of your own home. The device is blocky and rather fitting, and it will go anywhere nicely. This is the device’s main advantage over the much larger tank heaters. The second advantage is that this water heater can trim up to 20% off your electric bill. With efficiency such as that, it is hard not to like this device.

Alas, Tempra is not without problems. The device is not the most affordable one, carrying a hefty price tag. But the real problem is installation. The device is very hard to install by your average Joe, as you need to know a lot about plumbing as well as to be a good electrician. That’s why you’ll probably choose to rely on professionals, but that will ramp up your expenditure for the unit significantly.


  • A very efficient system; reduces your total power expenditure by up to 20%.
  • The unit is very compact and its blocky design makes it perfect for fitting into corners and out of the way.
  • The unit is very reliable and very sturdy.


  • The device is not as efficient in colder climates, as it overexerts itself, increasing power expenditure.
  • The device has trouble with harder water and less than ideal pH (above 7).
  • The device is hard to install and you will most likely need professional help. This will also increase the overall cost of the whole unit, adding to the already costly heater.

Eccotemp Systems L5 Portable Tankless Water Heater and Outdoor Shower

If you’re looking for a product that will fit well in your cabin, then you should definitely check out the Eccotemp Sytems’ L5 portable heater and shower. This little thing is quite affordable, and is amazingly portable and easy to install.

For anyone wanting warm water at their campsite or cabin, this heater could not be a better choice. It comes with all possible adapters, and installation is a breeze. The heater is able to deliver about 1.4 gallons of hot water per minute, which is more than enough for a single shower.

On other note, the device uses 2 D cell batteries that can be recharged. This is very useful, as you don’t have to mess with electrical cables every time you want to relocate it. The device is pretty small, and can thus be easily carried around. It also comes with its own showerhead.


  • A very compact and portable water heater and outdoor shower, perfect for cabins, campsites, even washing cars and the like.
  • Comes with every adapter you need and a showerhead. The installation is quick and easy.
  • The device uses onboard batteries so you would avoid messing with electrical installations every time you want to move it.


  • Small flow capacity. Not intended for the entire household.
  • The system experiences issues with heat at 5500 feet and beyond.
  • The system seems to be sensitive to the wind in that it will shut off when an ample amount hits it.

Stiebel Eltron Tempra 29 Plus Electric Tankless Water Heater

Like we said, the Germans are matchless when it comes to machines and devices of all kinds. We already talked about Stiebel Eltron’s Tempra 24, and we praised it for its efficiency and small size, but condemned it for the technical difficulties when installing. Tempra 29 is pretty much the same device, only this time it is more powerful, but just as efficient and complicated.

Just like with the 24, the overall consumption of electrical energy with this device will surely drop by 20%. Tempra 29 is very fast, and you will get hot water almost instantaneously. However, the system is prone to cold water sandwiches from time to time, so don’t just jump into the shower but wait for about 10 seconds for the stream to become steady.

The heater is fairly small for its power, about the size of a satellite TV box. It has a digitalized display where you can set the water temperature to anywhere between 80 and 120 degrees Fahrenheit. The system is a little simpler to install, but you will definitely need professional help, at least with electrical installations. The system also runs on very high amperage (about 150) and you will need to keep that in mind when putting up the system.


  • A very efficient system, reduces electricity consumption by up to 20%.
  • Compact and small, will not get in your way.
  • The system provides unlimited hot water supply, and has very high flow capacity.


  • You will need professional help to install the system.
  • The system leaves a little bit of water that cannot be cleaned out. The water does not cause damage if frozen.
  • The device alone is quite expensive, and you will need to pay extra for the professional help.

EcoSmart ECO 18 Electric Tankless Water Heater

Unlike its cousin, the ECO 27, ECO 18 is a water heater intended for use by people living in warmer climates. The heater works with water which temperature exceeds 62 degrees Fahrenheit. Just like its cousin, ECO 18 is highly efficient, rated to 99.8% energy efficiency.

The reason behind the device’s incredible efficiency is the self-modulating technology it features. This technology allows the machine to track the temperature of the water, and apply exactly enough energy to heat it the desired temperature. By applying the correct amount of energy, the system does not overexert itself, and saves you a lot of money on your electrical bill.

As far as flow capacity goes, the system is a bit weaker than its cousin. This particular heater can deliver about 2.5 gallons of hot water per minute, allowing for maybe two water efficient showers to run simultaneously. The product is also quite affordable, which is definitely a plus, and very easy to install.


  • A very affordable system, compact, small and efficient.
  • The heater possesses self-modulating technology, allowing it to apply just enough energy to heat the water to a certain level, increasing efficiency.
  • The system can be installed by yourself.


  • Not viable for use in lower temperatures and colder climates.
  • The warranty only covers systems installed professionally.
  • Prone to cold water sandwich effect.

Best Gas Tankless Water Heater

The Best Gas Indoor Tankless Water Heater - Takagi TH-H3-DV-N - Editors' Choice

However, if you’re not impressed with Takagi T-KJr2’s 6.6 gallons, Takagi has an even more powerful water heater. The TH-H3 Condensing Gas Water Heater is the pinnacle of efficiency and effectiveness. Just like the previous model, this one is also very small and compact, but abundantly more efficient and faster. If we were impressed by the T-KJr2, then TH-H3 blew our minds.

So, why all the ranting about this model? Takagi H3 can deliver up to 10 gallons of water per minute. This is enough for four showers (and they don’t even have to be energy efficient) and a dishwasher or a washing machine. With this model, you will never be at odds whether the unit will deliver enough hot water, and will you be able to take a shower while the washing machine finishes washing the laundry.But the H3 goes even further. Many gas heaters use pilot lights. The pilot lights can be a bit unstable. That is why H3 uses a completely computerized safety system, and utilizes no pilot light.

One more note about this product. For all its efficiency, this water heater is not as effective in the cold climate. At lower temperatures, the unit will suffer a drop ion efficiency, and will be able to produce about 3 showers’ worth of hot water.


  • Amazing flow capacity; the heater is able to produce 10 gallons of hot water per minute.
  • The water heater uses no pilot light, making it very safe; the chances of it exploding are minimal.
  • Very compact and space saving device.


  • Due to its outstanding features, the heater has quite a price tag on it (costs almost twice as much as the KJr2).
  • The efficiency of the heater drops significantly in colder climates (four showers to three).
  • The device can be quite loud at times.

Takagi T-KJr2-IN-ING Indoor Tankless Gas Water Heater

If you require something powerful, high-tech and compact, then Takagi Natural Gas Water Heater is the thing to get. This small, blocky and unassuming little heater is not to be underestimated – it is a real beast. After all, it comes from Japan, and the Japanese specialize in compact devices that are as efficient as their bigger and brawnier counterparts.

What makes this model a contender for the best gas water heater is its incredible power and capacity. Gas is much more effective when heating is needed, Takagi works very swiftly, heating the water in mere seconds. But what’s most impressive is that the device can deliver up to 6.6 gallons of water per minute, which is more than twice that of the ECO 27.

Of course, since the water heater is using gas, you will have to vent it. But this particular Takagi requires horizontal ventilation instead of usual vertical one the unit, however, does not suffer from any deficiencies in its efficiency, so it’s totally fine. On that note, you would think that, with such a powerful device, you will have start seeing a much heftier gas bill, but the device is so efficient it cuts the gas spending by about 40%. This is indeed a strong contestant for the title of the best hot water heater.


  • A very effective gas heater, able to deliver a total 6.6 gallons of hot water per minute.
  • The heater is very efficient, cutting the gas expenditure by about 40%.
  • The heater is very small and compact, which makes its efficiency, effectiveness, and speed all the more impressive.


  • The heater is prone to the cold water sandwich effect.
  • The heater is pricey to install and must be installed by professionals.
  • The system is not as efficient in cold climates, and you may experience trouble with freezing.

Takagi T-KJr2-IN-LP Indoor Propane Tankless Water Heater

Yet again, we have a Takagi product on our hands. Takagi, as we said, is a Japanese company, and one of the best companies in the world. It produces some of the best tankless water heaters in the entire industry, and some of the most compact. This tendency for Japanese products to be in such small size comes for experience with incredibly small and space-efficient apartments predominant in Tokyo, so every has to fit in just right.

That is exactly the idea behind Takagi T-KJr2-IN-LP. As you may have noticed, this heater carries the same name as the T-KJr2 we mentioned earlier. However, there is a difference between the two, albeit slight. The KJr2-LP runs on propane. Aside from that, the units are completely the same. They both have the same BTU (140.000) and the same flow capacity of 6.6 gallons per minute.

That being said, both units share the same disadvantages. Though gas powered units have a tendency to be more powerful, they are also much less reliable in cold weather. In colder climates, you may experience a drop in the overall performance of the unit.


  • A very effective gas heater, able to deliver a total 6.6 gallons of hot water per minute.
  • The heater is very efficient, cutting the gas expenditure by about 40%.
  • The heater is very small and compact, which makes its efficiency, effectiveness, and speed all the more impressive.


  • The heater is prone to the cold water sandwich effect.
  • The heater is pricey to install and must be installed by professionals.
  • The system is not as efficient in cold climates, and you may experience trouble with freezing.

Well, that’s it for our tankless water heater reviews and our buying guide. We hope you learned something from the guide, what makes the best electric tankless water heater, and that you’ll have a much easier time picking out the heater for yourself.

Also, here we want to let you know what products we favor the most. We will unveil our best tankless water heater, and our best value product.

Our best tankless water heater award goes to Takagi TH-H3-DV-N Condensing High-Efficiency Gas Indoor Tankless Water Heater. This particular heater is gas operated, and has amazing flow capacity. That being said, the heater is incredibly small and efficient, which is why, in our opinion, it stands much higher above the competition.

The best value product, and possibly the best electric hot water heater in our opinion, is the EcoSmart ECO 36 Electric Tankless Water Heater. With great capacity, and ability to work well in colder weather, the EcoSmart ECO 36 heater is an excellent product that will keep installation costs low, and provide simple and effective use, as well as great energy efficiency.

Tankless Water Heater Buying Guide

So, now that you know the top tankless water heaters, it’s time to learn something about them too. Without this knowledge, you might as well stare at the blank paper, as these numbers and words don’t mean anything to you, really. That’s why we decided to introduce this guide into to help you make a better, more informed decision.

So, what is a tankless water heater and what is the best water heater brand? Obviously, it’s a water heater. But the system and the size of the device is much different than, say a storage water heater. Storage water heaters have a huge tank that takes up a lot of space, and this tank stores water that is then heated and used. That being said, the tank can be depleted, and you need to refill it and reheat the water.

On the other side, tankless water heaters heat the water as it flows through it. This eliminates the need to wait for the water to be reheated, as the water is heated on the fly. In essence, they supply you with an endless stream of hot water. In this way, they’re faster and more efficient. They also conserve more energy and, ultimately, lower your water-heating bill.

Tankless Water Heater Problems


However, there is a problem (let’s call it that) with such heaters. Tanked water heaters have a very large capacity, making them suitable for supplying the entire household. With tankless, the capacity is measured differently. Such water heaters are rated to gallons per minute, or, how much gallons of water can they heat in one minute. What this often means in practice is that you will not be able to use more appliances that use hot water at the same time.

As your shower takes up a certain amount of hot water, as does a laundry machine and as does the dishwasher, your tankless water heater will need to meet the requirements for all of these for them to be useful.

Once again, you won’t be able to use several appliances at the same time, if your heater doesn’t have the same capacity.

Types of Tankless Water Heaters

Secondly, there are two types of tankless water heaters. These types are referring to the type of fuel they use for generation of energy. Mainly, there exist gas heaters and electric heaters. Both types have their advantages, as well as their disadvantages over one another, but they are both very much interchangeable and suited for use. This is more a matter of personal preference, and characteristics trade-off.

The Price Element

Speaking of electricity, you have to be wary of the electrical requirement of an electric heater. This is measured in amps. If you’re installing an electric heater, you have to check your circuit’s capacity, and purchase or adjust accordingly. That being said, if the heater’s requirement exceeds the system’s capacity, you might experience system overload, which might cause severe damage to the system and thousands of dollars in damage.

Lastly, electric water heaters also have one more advantage over gas heaters. They can operate much better in colder weather. In cold weather, gas compresses, and the gas-oxygen balance is offset, which makes the ignition much harder to achieve. That is why electric heaters are largely sought after in the Northern United States and Canada.

Overall, both heater types have their pros and cons, and you have to weigh them and figure out what are your needs and capabilities. That being said, they’re much more efficient than tank heaters, as they operate more smoothly while taking less space.

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