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8 Best Tankless Water Heaters

Everyone loves hot water, and having a tankless water heater means that when you turn on the faucet you’ll have on-demand hot water. They provide consistent hot water only when you need it, while saving you money on your monthly energy bills. These heaters are smaller than the traditional tank types, and the best tankless water heaters fit nicely into closets or similar tight spaced areas. Changing out an existing older heating system can also be done without too much work.

The invention of the tankless type has changed the way we use water. These modern marvels only heat water when required, whether for showering, washing dishes, doing laundry or just keeping your hands clean.

Today there are many water heating models to choose from and finding the best tankless water heater is easy.

This review highlights the top rated brands; types, features, Pros, Cons, and Comparisons.

Overview of The 8 Best Tankless Water Heaters

Prices pulled from the Amazon Product Advertising API on:

1. Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater

Rinnai RUC98iN Ultra Series Natural Gas, Twin Pipe

The Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater is an energy-efficient option for heating water throughout the home.

The higher degree of energy efficiency that this device has is achieved with the use of condensing technology. This allows this device to deliver water more efficiently and makes this one of the best tankless models.

This model is also designed to be compact, and as one of the best tankless gas water heaters, it can easily be installed in different parts of the home.

Main Features

  • This product includes condensing technology for more efficient water delivery
  • It has high energy efficiency, factor 0.96.
  • A dual venting option means that you can choose between concentric and PVC venting options i.e. you can choose which one will be the easiest option for you
  • The space-saving design makes this heater very compact, and as a result, it can fit in various areas of most homes
  • GPM rate of 10GPM

What We Like

  • The device is easy to install
  • You will get savings on your electricity bill (you’ll need to invest in the cost of the machine, but after that, you will certainly notice savings)
  • Quiet – as opposed to some other models, this device runs quietly without too much noise when heating
  • Temperature Control – you can easily adjust the temperature of the water with accurate temperature control
  • High GPM rate

Minor Drawbacks

  • You’ll notice a change in temperature if you open another tap while the machine is running, but this will only be for a short while
  • Water takes time to be heated, which means a bit of water wastage when waiting for hot water to come through
  • The device can be a bit expensive


This is an energy efficient option for those who are concerned about saving on long-term expenses and who are conscious of their environmental impact.

With easy to adjust temperature settings, the device is a convenient option because it is easy to use and gives you two different venting options for ease of installation.

While you might struggle with the device if you have low water pressure, this isn’t a problem that a plumber can’t fix.

The best use of this device will be in a home with decent water pressure, where the owners can afford to invest in this device and supply the gas needed to run it.

Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater, Twin Pipe


2. Ecosmart ECO 27 Electric Tankless Water Heater

EcoSmart ECO 27 Electric, 27 KW at 240 Volts, 112.5 Amps with Patented Self Modulating Technology

With components made of copper and stainless steel, this is one of the best brands and is made of solid materials that can withstand differing temperatures. This means that the device is made of materials that can last.

The Ecosmart ECO 27 Electric Tankless Water Heater is also compact and comes with a WaterSense certification, which means that it is energy and water efficient. In fact, this device comes with an energy efficiency rating of 99.8, which is very high!

This product is lightweight and compact, which makes it easy to install. It is also capable of heating 3 gallons of water per minute i.e. a flow rate of 3GPM.

Main Features

  • Compact
  • Made of copper and stainless steel
  • WaterSense certified
  • Energy efficiency rating of 99.8%
  • Able to heat 3 gallons of water per minute (3GPM)

What We Like

  • Easy to install
  • Can be operated remotely
  • Digital temperature control
  • Compact size with a sleek design
  • Copper and stainless steel elements can be easily replaced
  • Well suited for low temperatures
  • Comes with brass top to prevent electrolysis
  • Equipped with copper heat exchanger and automatic resettable thermostat

Minor Drawbacks

  • The machine doesn’t come with a plug, so you will need to wire it yourself
  • Users have reported that trying to claim the lifetime warranty on this device is very difficult


With a WaterSense certification, you know you are buying one of the best tankless water heaters and a product that is both water and energy efficient.

The best use for this device is in a small home where there is a constant supply of electricity and water, and where energy efficiency is a priority.

EcoSmart ECO 27 Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self Modulating Technology


3. Takagi T-D2-OS-NG Best Natural Gas Tankless Water Heater

Takagi T-D2-OS-NG Outdoor, Natural Gas

The Takagi T-D2-OS-NG is another one of the best gas tankless water heaters on the market.

In this case, the device includes a remote and has an 11,000- 1999,000 BTU/hr rating. This rating signifies how much heat it can supply. As you will notice from reviews of similar types of devices, this product can supply quite a substantial amount of heat.

With a 0.82 energy factor, it will provide you with a fair amount of energy efficiency. With a 10 GPM flow rate, it heats up a reasonable amount of water at a time. In fact, if you compare this to other water heaters, it is a much higher rate than others.

Unlike other similar models, this machine needs to be installed outside. It does, however, include freeze protection so cold outdoor temperatures won’t be a problem.

Main Features

  • TM-RE30 remote
  • 11,000 – 199,000 BTU/hr
  • 82 energy factor
  • 0 GPM max flow rate
  • Outside installation only

What We Like

  • It is a good option for those who want to save on their electricity bill
  • Comes with a remote so you can adjust the device while staying inside the house
  • A 10 GPM rating is pretty solid and can supply you with on-demand hot water via more than one fixture

Minor Drawbacks

  • You’ll need to get this device installed outside. As a result, you might require some input from a professional which can end up costly
  • A 0.82 energy factor is not to be scoffed at, but for those looking for optimal energy efficiency, there are products with a higher rating


This device can provide all of the solid features you are looking for from this type of device. When you look at tankless water heater reviews, this is one of the best on our list, it certainly meets all of the necessary requirements.

It might not have the highest energy rating, but it’s a perfect option for those looking for something solid within a medium to large home, as the BTU rate is quite high.

With the high flow rate, you are also guaranteed to be able to use multiple fixtures at once.

Takagi T-D2-OS-NG Outdoor Tankless Water Heater, Natural Gas


4. Stiebel Eltron Tempra Plus Electric Tankless Water Heater

Stiebel Eltron 224199 240V, 1 Phase, 50/60 Hz, 24 kW Tempra 24 Plus Whole House Tankless, Advanced Flow Control

The Stiebel Eltron Tempra Plus Electric Tankless Water Heater is made by a German brand with a good reputation. Naturally, this is always a good thing when it comes to buying a mechanical product.

As can be expected, this is one of the best powered by electricity available. It is also an efficient device with attention to detail. One of the outstanding features is that even though it provides a medium flow rate of 4 gallons per minute, you don’t have to worry about fluctuations in temperature, which is a bonus!

With digital temperature control and no need to worry about venting with installation, this is one of the most efficient electric devices and is well suited to both residential and commercial use.

Main Features

  • Advanced flow control with microprocessor technology – provides consistent heat rate even if the flow rate changes
  • Digital temperature control
  • 4 gallons per minute, which is a medium flow rate, but with flow control can provide the same temperature of water to multiple faucets

What We Like

  • Easy to install as it doesn’t require venting
  • Sturdy steel casing
  • Geared for residential and commercial use
  • 3 year limited warranty
  • Made by a company with a solid reputation

Minor Drawbacks

  • Energy efficient but does require a substantial amount of power to run. Keep this in mind if you are worried about energy bills or the environment
  • A bit more expensive than some other models


The advantage of this electric device is that no venting is required, unlike gas units. This machine is also backed by a decent warranty and is made by a reputable company, so you can be assured that you are buying a quality product.

The best use of this device is for those who don’t mind paying a bit extra for a heater that can provide consistent heat across multiple faucets, and who want a quality machine with a guarantee. This is also a perfect option for those who would prefer to install this kind of product indoors.

Stiebel Eltron 224199 240V, 1 Phase, 50/60 Hz, 24 kW Tempra 24 Plus Whole House Tankless Electric Water Heater, Advanced Flow Control


5. Rinnai RL94iP Propane Tankless Water Heater

Rinnai RL94IP Water Heater, Large, Silver

The Rinnai RL94iP Propane Tankless Water Heater is a compact option for those looking for heating options for smaller homes or even commercial properties.

With a flow rate of 9.4 gallons per minute (GPM), this is one of the best tankless water heaters and can provide a solid flow of water. It’s got a heavy-duty heat exchanger which makes it able to cope with a high level of on-demand heating.

As this machine uses propane as a source of fuel to heat the water, it will need to be stored outside. That being said, it does have freeze protection to protect the device from cold weather.

Main Features

  • Compact size (14 x 9.3 x 23 inches)
  • Temperature lock
  • Digital controller
  • Heavy-duty heat exchanger
  • 4 GPM rate
  • Freeze protection

What We Like

  • Sleek, compact design
  • Can even be used for mobile homes, which is quite rare
  • Energy efficient, low emissions and has an electronic ignition (i.e. no permanent pilot light)
  • Parts are replaceable
  • Systems are included to ensure longevity
  • Leak detection
  • Authorized access setup
  • 12-year warranty

Minor Drawbacks

  • The device is expensive but has a commercial grade heat-exchanger
  • To qualify for the warranty, you need to have this product installed by a licensed provider, which can be costly


Even though it is expensive, you are guaranteed a product that can provide water for larger and smaller homes, especially since it is equipped with a heavy-duty heat exchanger.

With a wide variety of features, the device is one of the best tankless models and is equipped to deal with the cold, even though it needs to be installed outdoors.

The best use of this product is in an average sized home or mobile home, where it can provide on-demand hot water to a number of fixtures at the same time.

Rinnai RL94IP Water Heater, Large, Silver


6. Atmor AT-D18TP-AZ Instant Electric Tankless Water Heater

18kW / 240V Water Heater, 3.7 GPM, 75 Amps, ThermoPro Series with Digital Thermostatic Control

Atmor is a company that has over 40 years of experience in manufacturing products. It certainly gives a good impression and provides a high level of trust for those looking for one of the best electric heaters. With this type of history, you’re also buying something that can last.

As one of the best tankless water heaters, the Atmor AT-D18TP-AZ with digital thermostatic control operates on smart flow technology. This means that the device will adequately control the amount of flow needed to provide water to multiple fixtures.

Main Features

  • Digital temperature control which can adjust the temperature anywhere between 90- 137 degrees Fahrenheit
  • 9 GPM flow rate
  • Specially designed to heat cold water (37 degrees Fahrenheit)
  • Self-modulating technology that adjusts energy consumption according to the amount of water required

What We Like

  • Durable stainless steel interior that is corrosion resistant. This allows for heat efficiency and longer life expectancy
  • Good value for money

Minor Drawbacks

  • Not as powerful as gas water heaters
  • Lower flow rate means that it will be challenging to use more than one water fixture at a time


This device is a value for money option and is made with durable materials by a reputable company.

However, with the low flow rate, this device is better suited to smaller homes or single-use applications.

18kW / 240V Electric Tankless Water Heater, 3.7 GPM, 75 Amps, ThermoPro Series with Digital Thermostatic Control


7. Rheem RTEX 13 Electric Tankless Water Heater

Rheem 240V Heating Chamber RTEX-13 Residential

The Rheem 240V RTEX 13 Electric Tankless Water Heater is an electrically powered heating device that is made of durable materials and also includes self-modulating power control.

This means that the device will automatically detect how much water is being required, and adjust power usage accordingly.

As with all the best electric tankless heaters, this device also has an adjustable thermostat control.

Main Features

  • Adjustable digital thermostat control on exterior with LED display
  • Durable copper heating elements
  • Self-modulating power control

What We Like

  • Simple to install as cable and adaptors included
  • 8% energy efficient,
  • With a water-saving showerhead, you’ll be getting a flow rate of 1.5 GPM
  • Users report savings on electricity of up to 30%

Minor Drawbacks


As with the product reviewed above, this electric device is great for those who are looking to install a water heating device indoors. It is perfect for single use hot water applications.

Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater


8. Eccotemp L10 Portable Propane Tankless Water Heater

Eccotemp L10 2.6 GPM Portable Water Heater, 1 Pack, White

We’ve covered many examples of the best above, but how about a device that is more suited to being moved around and used for outdoor applications?

If you’re a fan of the outdoors, but you still enjoy a good hot shower, this is the product for you. Made by a leading manufacturer with 15 years of experience, the Eccotemp L10 portable heater runs on propane and is geared for outside use.

On the plus side, it is compatible with most standard plumbing fixtures, so it will be easy to install in a variety of different locations.

Main Features

  • 6 GPM- up to two showers running at the same time
  • Designed for outdoor use
  • Compatible with most plumbing fixtures
  • Portable and lightweight
  • Manually adjustable control system
  • Water pressure control system

What We Like

  • Protective stainless steel rain cap
  • Purchase includes a CSA regulator and garden hose
  • Includes a battery ignition backup that only starts when water is running
  • Also includes a safety timer that shuts off after 20 mins
  • Proven to supply water at high altitudes
  • Easy to install

Minor Drawbacks

  • The product only runs off liquid propane and so it can only be used outdoors
  • You need to purchase a shower head and hose separately, and it’s only really set up for this functionality
  • Can’t be used indoors


This device is one of the best portable tankless water heaters available as it is efficient, safe, and cost-effective.

However, it is only really designed to be an outdoor tankless water heater. With this in mind, it is really geared towards those who like to take the convenience of a hot shower with them when they go to their cabin or outdoors.

Eccotemp L10 2.6 GPM Portable Tankless Water Heater, 1 Pack, White


Choosing The Right Water Heater According To Type

Tankless heaters can be grouped into different categories depending on the power or fuel source they use, as well as their intended application.

You might be asking yourself, “what is the best tankless water heater?” Of course, there are advantages and disadvantages to using each one.

To help you get a better understanding of what is available, here is a breakdown that will help you to choose the right one according to type, and make sure that you are choosing the best option for your particular situation.

Gas or Propane Heaters

Gas tankless water heater uses either natural gas or propane to power the process of heating up your water. They are an energy-efficient and cost-effective option for your home.

However, as you can imagine, using gas or propane inside a building does come with risks. This is because improper ventilation can lead to leaks, or in the worst-case scenario, an explosion.

For this reason, many of these devices need to be installed outside. Obviously, this will need to be a consideration if you live in a very cold area, or don’t like to store your devices outside. That being said, with the right venting options for natural gas, you can install this kind of appliance inside as long as there is proper ventilation.

Electric Heaters

Tankless water heaters can also be electrically powered, although it has to be said upfront that they won’t be as powerful as a gas or propane water heater.

The advantage of electric models is that they are easier to install, as you can safely put them indoors. Many of these types of products are better suited to single-use applications, for example, in a bathroom where the hot water required only needs to come out through one faucet.

Ultimately it all depends on your plumbing, your water pressure, and if there are water restrictions in your area or not.


Tankless type heaters come in various sizes. It really all depends on what amount of water you need, and the space available in your home to install it (whether indoors or outdoors).

In other words, smaller devices will be more suitable for smaller or mobile homes, while something bulkier might be needed for more commercial applications.

Indoor or Outdoor

Overall, the best water heaters that use gas (either propane or natural gas), need to be installed outdoors for safety reasons. Therefore, in colder climes, these machines will need to include freeze protection.

Electric devices, on the other hand, can be installed indoors. However, they don’t always provide as much power as devices that use gas.


For those who are relatively handy and able to handle a set of tools, a DIY installation may be an option. Keep in mind that you might have to lay pipes, drill into the wall, connect electrical components, and ensure adequate ventilation among other things.

Of course, not everyone is comfortable with setting up this sort of appliance themselves and prefer to seek professional assistance.

With this in mind, select your new water heater appropriately as they do involve varying levels of difficulty when it comes to the installation.

Final Thoughts

As you can see from the in-depth list above, when it comes to the best tankless water heater, there are a variety of options available.

Ultimately, making the choice between the variety of tankless water heaters brands models comes down to your own personal preferences, your budget, and whether or not you’re willing or able to do a bit of DIY to get the product installed.

Overall, gas and propane models are more suited to larger homes and outdoor applications. Electric heaters are easier to install indoors but are better placed to provide hot water for single fixture applications.

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