tankless water heater on wall

Our BEST Tankless Water Heater Reviews (for 2019)

The Best Tankless Water Heater Reviews for 2019

Today we are turning our attention to your hot water needs, and bringing you tankless water heater reviews of what we believe are the best products on the market.

Maybe you’ve heard how much more convenient and economical these products can be.

Maybe you’re intrigued by the fact that they heat water only when you need it, eliminating the need for a large and cumbersome tank.

Maybe you want to be more Eco-friendly and have chosen to invest in the best tankless water heater as a way to lower your costs and help the environment in the process.

Or, maybe your old heater just sprung a leak for the umpteenth time and you’ve had just about enough of this nonsense.

Whatever the reason, we’re here to help you choose an appliance that suits you.

Below you will find reviews of the best electric and gas-powered tankless water heaters, divided into two groups.

The first one features bigger and more powerful units capable of meeting the demands of large households or small office buildings.

In the second we showcase more affordable, but nevertheless viable units that you can use to adequately supply smaller homes or apartments.

We’ve also outlined some key factors you should consider before purchasing anything.

These will help you determine what product will get you the most bang for your buck while being suitable both to your climate and living conditions.

Following this guide will streamline your decision making and help you understand exactly what you are buying.


Name Type Suitability Max. Temperature (F) Rating Price
Tempra 29 Plus Electric Indoor 140 4.7 $$$
Ecosmart ECO 27 Electric Indoor 140 4.4 $$
Takagi T-KJr2-IN-NG Natural Gas Indoor 140 4.2 $$
Ecosmart ECO 18 Electric Indoor 140 4.2 $$
Rheem RTG-64XLN Natural Gas Outdoor 140 4.2 $$$
EcoSmart ECO 11 Electric Indoor 140 4.3 $$
Eccotemp L5 Liquid Propane Outdoor 140 4.3 $
Rheem RTE 13 Electric Indoor 125 4.2 $$
Eccotemp L10 Liquid Propane Outdoor 140 4.1 $$
Rheem RTE 9 Electric Indoor 125 3.9 $$


Tankless Water Heaters: Our Picks

1. Stiebel Eltron Tempra 29 PlusStiebel Eltron Tempra 29 Plus

Stiebel Eltron is a long established European brand that has been making a foray into the US market in recent years as well. Their newest model, the Tempra 29 Plus is a strong contender in the market today.

Many professional reviewers and satisfied customers alike consider it to be a top quality tankless water heater. Let’s take a look and see what exactly makes it so.

The first thing that pleasantly surprised us was its advanced temperature control system. Regardless of the amount of water you use, the Tempra is sure to deliver a constant flow on demand.

Since it is tankless, there is no loss of energy due to water having to be stored in the product itself. This also makes it much more practical, enabling installation closer to points that draw off the water and ensures minimal energy expenditure in order to get it there.

The product comes in various sizes depending on your household’s needs and the climate you live in. Therefore be sure to get the model that is best suited to your daily requirements.

Speaking of which, the Tempra 29 plus tankless water heater delivers up to 8GPM for up to 6 heating elements. Its heater is engineered to provide you with water at the precise temperature you currently desire in less than a minute.

The built-in thermostat is very precise, having been outfitted with an Advanced Microprocessor technology, ensuring that with the turn of its knob you will actually get the kind of temperature you had in mind. This ranges from 86 to 140 degrees Fahrenheit which does not fluctuate regardless of volume.

Another beneficial feature is that this product doesn’t need to be vented to the outside. Installation can therefore be carried out more cheaply and efficiently.

Unlike conventional gas heaters where a sizeable percentage of energy can be lost due to heat dissipation that occurs through pipes, the Tempra’s design makes for an almost complete transfer of electric energy into heat.

Since there are no other factors to consider, such as the outdoor environment or having to ensure an optimal air to gas mixture, no heat is lost in this process.

Stiebel Eltron offer a generous seven year warranty, provided the product was installed by a licensed technician. During the whole period leakages that might occur are covered, and there is also a shorter three year period that covers possible workmanship defects.

While you have to ensure that your electrical service has a minimum of 200 AMP and the installation costs might prove to be substantial, the Tempra 29 Plus could be one of the best investments you make in the long run.

Its superb craftsmanship as well as its potential to save you a lot of money on electrical bills down the road make it the best choice for a more efficient and greener household.

2. Ecosmart ECO 27Ecosmart ECO 27

Another tankless water heater to consider when supplying your house with on demand hot water is the ECO 27 manufactured by Ecosmart. The premise is similar – in this product you have a very energy efficient system that adapts itself to most climates and can be used both for domestic hot water and for operating a whole baseboard system.

The ECO 27‘s most striking feature is its ability to operate in very cold climates. Water that reaches into the thirties can be heated up to as high as 105 degrees Fahrenheit at a flow rate of 2.7 GPM.

At temperatures as low as that, the amount of water that can be heated up in a pinch is naturally somewhat lower than usual, but definitely enough for a shower or other smaller needs.

The flow does seem to fluctuate a bit in the first minute, but after that there have been no other problems reported.

It’s other major selling point is the unit’s energy efficiency – the manufacturer claims that by using it, costs associated with heating can be cut by up to 60 percent.

The entire system is of a sound build and is compact due to the fact that it does not require a tank. The unit comes with replaceable elements that can be interchanged with ease, making potential repairs a less painful experience.

It’s design is sleek and functional – a digital display above its knob makes all the information and settings readily available.

Customers will be pleased to know that the ECO 27 comes with a lifetime warranty applicable to the United States and Canada. There are some reasonable limitations however.

One is that the warranty only covers parts, meaning you’ll have to pay for labor yourself. The other is that in order for the warranty to be honored, the installation of the water heater as well as all repairs need to be conducted by a licensed professional.

Judging by some Amazon customer reviews and our personal experience, the time it takes for hot water to actually arrive at the designated tap is somewhat prolonged. When it does arrive however, expect the temperature to be constant and the flow to be uninterrupted.

As with the other water heater above, the installation process can become quite tedious as well.

Setting up a product like this requires both plumbing and electrical work to be done, increasing the initial costs and increasing the time before real savings can be felt in the household.

As with most of its competitors, the ECO 27 requires a strong electric service, 240 volts to be exact, meaning that some households might need to upgrade in order to accommodate it.

Finally, the Ecosmart ECO 27 seems to be the best choice for people who need a steady and reliable source of hot water even in unforgiving climates. It does have a few shortcomings, but its adaptability and energy saving features more than make up for this, making the ECO 27 a viable purchase.

3. Takagi T-KJr2-IN-NG

The market wouldn’t be what it is today if not for Takagi, a Japanese manufacturer that was the first to introduce the tankless heater to American consumers.

The T-KJr2-IN-NG is one of the smaller units on our list, but its features and performance more than make up for its lack of size, making it one of the best choices if you wanted a gas tankless water heater.

It’s performance is that of an equivalent 40-gallon tank type water heater, but without the added hassle of having to heat an actual tank and with the accessibility a much smaller size can bring.

It’s best and most important feature is an uninterrupted supply achieved in part by the company’s implementation of an air-fuel ratio sensor which actively checks for and can help reduce hazardous emissions.

This is also a very safe system – in the event of too much hot water its sensors turn it off and prevent the unit from overheating.

Built-in DIP switches assure that you can adjust the unit to almost any climate type with ease. Added to that are protection from electrical surges as well as freeze protection and a step-by-step troubleshooting guide which should help to resolve most common issues.

Its longevity is nothing to scoff at as well – with proper use the The T-KJr2-IN-NG can work for more than a decade without any problems.

The T-KJr2-IN-NG is gas-powered, requiring no electricity to operate. Its gas input ranges between 19500 and 140,000 BTU/h, with a flow rate of 6.6 GPM. As with other gas-powered models, this one requires outdoor venting to be provided.

The installation process is straightforward enough, and although it comes with a simple step-by-step guide, be sure to have the installation performed by a licensed technician so as not to void the warranty.

Attempts at DIY can cause an installation to be faulty, so use of better judgement is encouraged.

Although customer reviews suggest that this water heater is ideal for smaller households, some disadvantages are apparent as well. On one hand, insisting on a professional installation can hurt your budget in addition to purchasing the heater itself.

What’s more, due to the fact that gas poses a serious fire hazard when used in proximity with electrical equipment, it can not run at the same time as other household appliances, making the additional time management something of a chore.

In the end, if you are on the fence on whether to exchange your old and leaky water heater for a new tankless one, the The T-KJr2-IN-NG is a solid choice. Its small size and wide availability make it one of our best choices for this year.

4. Ecosmart ECO 18

Ecosmart ECO 18Another one of Ecosmart’s tankless water heaters, the ECO 18 is somewhat smaller and a bit less capable than its big brother, the ECO 27, but it is still one of the best options to consider if your day-to-day requirements are somewhat smaller than what its bigger counterpart can supply.

What makes this model stand out is that it only needs an activation flow of 0.25 GPM which is less than most competitors. The flow as well as the current temperature are measured with a set of sensors that help to ensure a consistent temperature and quantity.

The ECO 18 might not be the best choice for colder climates where water can dip below the 40 Fahrenheit mark, but in temperate climates it manages to output a continuous stream without much fuss at a flow rate of about 2.5 GPM.

Ecosmart prides itself in engineering energy-efficient products that save their buyers money in the long run. It is no different with this model of which the company claims that it can cut down on costs by up to 60 percent.

Due to its build, the ECO 18 is not suitable to be installed in outdoor areas susceptible to rapid temperature changes or increases in humidity. It is content however to find its place inside apartments and smaller houses where it will be able to satisfy demand both in the bathroom and the kitchen, so depending on your requirements, this could be the best choice.

Temperature adjustments are easy and precise due to the built-in digital display and responsive knob.

You can install the heater yourself since its instruction manual explains the whole process in an easy to understand manner. As with each tankless water heater we’ve mentioned before, this leads to the warranty being void, so consider that before committing to doing anything yourself, especially since it comes with a life-time warranty.

Installation of the ECO 18 requires an electrical service of at least 150 amps, but it does not need venting to the outside.

At the end of the day, the ECO 18 is a unit that might fall short of some buyers’ expectations, but will be perfect for customers that want a small yet capable device that gets the job done in a cost-effective and clean manner.

Its low flow requirements ensure that it will work in apartments and houses with plumbing that might not be optimal, and its compact size will make it blend into such environments seamlessly.

5. Rheem RTG-64XLN

Rheem RTG-64XLNGoing tankless is a new experience for most people, and a gas-powered unit is just the thing to start you off.

Enter Rheem’s RTG-64XLN, a robust outdoor water heater capable of supplying you with hot water even in somewhat harsh environments. Temperature adjustments are easy to accomplish either manually or by use of a remote control.

Its water flow rate can reach 6.4 GPM in warmer climates, which is more than enough if you plan on operating more than one shower and sink simultaneously. Depending on the season and outdoor conditions, the flow can sink to as low as 3 GPM, which is still enough to supply you with ample hot water for the time being.

The minimum flow rate requirement for the unit to function properly is 0.26 GPM, meaning that it can perform its job adequately even in homes with older plumbing.

With a weight of 54 pounds, it can easily be positioned anywhere outside that you see fit.

The RTG-64XLN ‘s power requirements are about 150,000 BTUs, and its energy efficiency of 0.82 makes it competitive among similar products available today.

Even though it is a methane unit, one of the RTG-64XLN’s advantages is its “low NOx” function, a special feature that reduces the requirement for venting, saving you money on expensive steel equipment where a cheaper PVC equivalent will suffice.

Nevertheless, this unit needs to be installed outdoors as fume build-up is a real possibility and can potentially cause health risks. Installation is straightforward however, and Rheem makes it even easier for you by throwing in some extras, like temperature wire.

It might not be the best choice nor powerful enough to satisfy the needs of a larger household or that of a commercial building, but this unit is nevertheless a good choice for customers with more modest needs.

Its output does not fluctuate and the time it takes for water to reach your taps is satisfactory. Add to that its low emissions, and the RTG-64XLN becomes a hot water heater you should seriously consider when browsing for your next purchase. It does very well in our list of tankless water heater reviews and can still be the one of the best options to consider depending on your requirements.

The Best Affordable Models to Consider

1. The EcoSmart ECO 11 Tankless Water Heater

The EcoSmart ECO 11 Tankless Water HeaterWhat can we say, Ecosmart makes high quality products, hence three of them have found themselves on our list. The last one, and in our opinion, one of the best products within its price range is the ECO 11, a smaller more affordable variant of the aforementioned ECO units.

It’s size doesn’t diminish its performance however – the ECO 11 comes with most of the features we’ve come to expect from the more expensive models – a sturdy build, Ecosmart’s own energy efficient technology, a life-time warranty with conditions that are easy to uphold, and with a digital readout that makes controlling the unit simple and intuitive.

Its small size and light construction make the ECO 11 perfect for indoor use. This also makes it portable should the need to switch its location arise. It works best with water where temperatures don’t drop below 67 degrees Fahrenheit.

It can heat about 2 gallons of water in under a minute, supplying your bathroom or kitchen sink with enough water for quick daily tasks at a rate of 1.5GPM.

Thanks to its built-in self-modulating technology, the water this heater produces will always be at the exact temperature that you specify via its knob, which enables you to set how warm the water will be in increments of 1 degree.

The way in which it is constructed allows for heat exchangers to ensure that 99.8 percent of the energy used to power the unit is actually converted into useful heat.

You can install the unit in no time and it only needs a power source of 60 watts to function properly. As with other Ecosmart tankless water heaters, consider having it installed by a professional.

Alas, the ECO 11 does suffer from some drawbacks.

For starters, it is designed for separate cold and hot water lines, meaning that you can’t start using it as if your home has only one water line. Instead, a restrictor will have to be set up first for the device to function properly.

Apart from that, its small size means that not much volume can be produced in a short amount of time. It is recommended that it be used in conjunction with an existing heating system in larger houses.

In spite of all this, the ECO 11 is a smart, reasonably priced solution for a smaller household which doesn’t require that much hot water to be available at any given time.

If one takes this into consideration, the unit does what it’s supposed to adequately, providing you with water and savings at the same time.

2. Eccotemp L5

Eccotemp L5Many smaller-sized units feature portability as one of their prime strong suits. If that alone doesn’t satisfy you however, and you’d like your water heater to come with a shower head, the L5 from Eccotemp has got you covered.

With a capacity to deliver up to 1.4 gallons of hot water to its shower, the L5 should be able to handle most of your outdoor hot water needs. It uses propane as its power source, ensuring that the water will heat up quicker than it would in an electric model of similar size.

The propane consumption clocks in at 37,500 BTU. Its built-in regulator ensures that the heater provides uninterrupted hot water as long as there is propane, and that can reach up to 18 hours if connected to a 20 gallon gas tank.

  • To ensure safe operation, there is also a shut-off timer which shuts the gas off after 20 minutes of uninterrupted use have passed.
  • Pressure of 20 psi or higher is required for the unit to operate properly.
  • The supplied water can then be heated constantly from 80 to 150 degrees Fahrenheit, adjustable by a standard knob.

The L5 also comes with some welcome attachments. Included are a 1/2″ NPT to garden hose adapter, a shower nozzle that can be turned on and off via a switch, and a hardware pack.

Despite it being marketed as an outdoor heater, the L5 suffers from one annoying problem – its flame can be blown out by a mere breeze, forcing you to consider placement in a sheltered area. The accessories are also not of the highest quality and are prone to leakage.

Still, this tankless hot water heater is a fine outdoor unit. Setup is minimal and quick, gas consumption is reasonable, and it can even be used while camping. If you are the outdoorsy type but don’t want to forgo some of home’s comforts, this is the right product for you.

3. Rheem RTE 13

Rheem RTE 13Rheen’s RTE 13 is a small water heater that packs a big punch. With output reaching as much as 4GPI in the right climate and under the right plumbing conditions, this unit is able to provide more than one source with continuous hot water at once.

Heating by about 50 degrees results in an output of 1.75 gallons per minute. It has LEDs that light up indicators for standby and power, as well as its temperature controls.

Ideally, the RTE 13 should be set up in close proximity to the fixtures it will be supplying. It requires 240 volts and 60 amps, much more than most regular appliances, so make sure your home meets the requirement before purchasing.

Special care should be taken when installing the unit as an improper setup can cause power fluctuations and can decrease the temperature of the water being heated.

There is a one year warranty on parts and a 10 year one for its heat exchanger, with the same conditions as outlined in the tankless water heaters above.

The best value for money, surprising output capabilities for the price range and a compact build make the RTE 13 a good replacement for clunkier and more power-hungry models.

4. Eccotemp L10

Big brother to Ecotemp’s other model, the L10 isn’t as compact, but it provides hot water to remote locations and outdoor enthusiasts alike.

It can heat water up to a whopping 165 degrees Fahrenheit and uses a heating power of 74,500 BTU to do so. The lighter is battery-powered, making this tankless water heater suitable for use both in off-the-grid areas as well as in case of a prolonged power failure. It can even be fitted to work alongside other systems, like a water pump.

It comes with the same 20-minute shut-off timer which prevents overconscientious and ensures safe operation. The L10 is less cost-effective however, lasting for 12 hours with one 20 gallon tank.

It is accompanied by the same accessories, which unfortunately suffer from similar drawbacks.

The L10’s superior heating ability as well as its use of Eco-friendly propane gas make this unit one of the best options for anyone that needs just a little bit more than what its smaller brother can deliver.

5. Rheem RTE 9

Rheem RTE 9The last entry we’ll look at more closely is the RTE 9 from Rheem.

This boasts high energy saving capabilities and is better utilized for point of use applications. A high response time makes for a shorter wait for hot water to arrive.

It is a tankless water heater perfectly suited for use in small bathrooms, or even in RVs for use on the road.

The manufacturer states that it provides a flow of up to 3 BPM, but some dissatisfied users have pointed out that this is applicable only to short distances and the supply decreases the farther the source is from the unit.

The RTE 9 is also known to experience fluctuations in temperature if the flow is subject to rapid changes or is too high.

Although this might dissuade some from buying the RTE 9, its small frame and adaptability make it a sound option if your needs are modest or if you want a reliable source of hot water on the go. If you need something more than that, it’s best to go for one of the other options on our list.

Buying Guide

tankless water heater inside partsAs you can see, there are many factors one needs to take into consideration before committing to any one product. They can be summarized in a few key points:

Electric vs Gas-powered

Depending on your preferences and the infrastructure of your house or office building, electric heaters can be the best option.

Most of them do not require you to make serious alterations to your existing grid, they are very efficient, helping you cut power bills in no time. They also tend to be more compact and designed with cramped spaces in mind.

On the other hand, they tend to take a bit longer to deliver water at the adequate temperature, and their output is generally smaller.

Gas heaters are more rugged and most products are designed with the outdoors in mind. Their output is much higher so you can supply multiple bathrooms at the same time for example.

Their power source makes them a hazard to operate near electrical equipment though, and other safety precautions like proper venting need to be ensured before purchase as well as annual vent cleaning maintenance.

Climate and Plumbing 

  • Most manufacturers stress that not every model is suitable for every environment.
  • Smaller and less powerful models simply aren’t able to warm up freezing water to high enough temperatures in a reasonable amount of time, if at all, so might not be the best option for your needs.
  • You should always consult the handy charts found on manufacturers’ websites before purchasing a hot water heater that might not be suitable for your climate.
  • Bad plumbing on the other hand is a universal plight. Simply put, if your water pressure is low, your heater can’t do its job properly.
  • A lot depends on its ability to have access to a continuous source. Some models require a very small GPI for optimum performance, other ones require the pressure to be higher.

Budget and Requirements

  • You can’t expect to have hot water readily available in two bathrooms and two kitchens simultaneously with a smaller, less powerful heater.
  • We’ve shown in this tankless water heater guide that some have more than enough capacity to service such a need, while others are adequate for small home or apartment use.
  • The GPI is usually a good indicator – the higher the number, the more water is heated and produced in a given amount of time.
  • This may vary depending on the climate and plumbing, so take the number provided by manufacturers as optimum.
  • If you are on a budget, weigh the pros and cons of each reviewed heater. Some offer many features you would find in expensive models.
  • Other premium units exhibit some negative traits which might be crucial for your particular situation or preference.


Now that you have a more thorough understanding of tankless hot water heaters, their pros and cons as well as their characteristics, you’ll be better equipped to make an informed decision.

The selection is big and varied with ever more manufacturers coming to realize the long-term potential these appliances have in making customers’ lives easier and their energy expenditure less pronounced.

So, what is the best tankless water heater you ask?

Well, we’ve given you an outline of what you can expect to find. The answer to that question depends on your specific set of circumstances and personal preferences.

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