Best Condensing Tankless Water Heater (2021 Reviews)

Want to save on the bills piling up at home? Well, one sure fire way of doing that is by using the best condensing tankless water heater out there. Condensing tankless water heaters have become increasingly popular over the last few years, mainly because of how efficient and easy to use they are. Not only will you have hot water running through your whole house, but you won’t have to make a fuss about having to place tanks either in your home. Thus, we’ve written this article to help you look through our top 5 picks when it comes to these condensing water heaters.

In a Hurry? Here's Our Top Choice:

Takagi TH3DVN, Condensing Tankless Water Heater

Our pick for the best tankless water heater is the Takagi TH3DVN. It comes with a digital interactive display, and this means anyone can operate it with ease. It also rises in the ranks, thanks to the high 10 GPM it has, making it run multiple bathrooms at the same time. While it is very powerful, it is also very efficient and environment friendly, making it the best choice in our opinion.

Now that you know our top 5 picks for condensing water heaters, let’s look into each product in detail, and what makes them stick out for us!

5 Best Tankless Condensing Water Heater

Takagi TH3DVN, Condensing Tankless Water Heater

Takagi TH3DVN

Our first product in our list of water heater reviews is the best tankless condensing water heater in our opinion. This is the Takagi TH3DVN, and they ensure their products are designed to meet the needs of their consumers. This unit uses various types of materials in its production, but the most important one is the copper alloy, as this allows for 25% better heat transference.

The Takagi TH3DVN also boasts an amazing digital display, and this allows for anybody to be able to use it with ease, and not have any issues with temperature adjustments. It comes with a 10 GPM flow rate, making it able to run your home with ease, all without having to sacrifice on water temperature. Even when it comes to large houses, this model will be able to run 5 showers all at once, giving you an idea of its power.

The world has moved towards making environmentally friendly products nowadays, and the Takagi TH3DVN follows that route, as it is designed to make lower amounts of NOx emissions. While giving you clean and hot water, it also ensures to work with the environment as well. The one drawback of this unit, is its inability to provide the same performance in colder climates. It won’t be able to put out as much hot water as it normally does.

  • Has 25% better heat transference
  • Comes with a high 10 GPM flow rate
  • Can run up to 5 showers at a time
  • Low NOx emissions make it environmentally friendly
  • Does not have same potential in colder climates

Rinnai RUR199iN, Condensing Tankless Water Heater

Rinnai RUR199iN, Condensing Tankless Water Heater

The second on our list is the Rinnai RUR199iN, and this was barely edged out into second place. The Rinnai RUR199iN unit is another great tankless water heater, and would go great in any house. It also comes with a digital interface, allowing you to use it swiftly and with convenience.

With the technology placed into the Rinnai RUR199iN, you will never feel the need for any other water heater, as this can provide you with hot water at a very fast rate, and with its 11 GPM, you will be able to run your house with ease. It also has a very sleek look to it, thanks to the stainless steel build it has. What makes it even more convenient is its remote control ability. You can use the specific app for this water heater, to ensure you can set up specific times for when it needs to be turned on, and it can even be controlled when you’re out of your house.

Rinnai is great with their products and the RUR199iN is a good example of it. You can even choose to purchase from two different models, one made to be fitted outside, and the other one, inside. It even comes with ultra low NOx emissions, making it great for the environment. One drawback with this product is that it seems to revert back to a default water temperature, if there is ever a power outage.

  • Runs at 11 GPM flow rate
  • Can be controlled remotely to adjust temperature settings
  • Only operates when hot water is needed
  • Provides hot water on demand
  • Has Energy Star certification
  • Sometimes reverts back to default settings

Noritz NRC66DVNG, Condensing Tankless Water Heater

Noritz NRC66DVNG, Condensing Tankless Water Heater

Our third product is the Noritz NRC66DVNG, and is a great unit overall. It comes with two different heat exchangers; one of copper and the other is stainless steel. These work well in getting heat and retrieving wasted gas, and increase the overall efficiency of this product, making it a great condensing water heater.

The Noritz NRC66DVNG is also very small and lightweight, meaning it won’t get in your way, no matter where you install it. It also includes the great feature of having the ability to be controlled remotely, making sure you won’t have to bother getting up close and personal with it, to make any changes to the temperature of the water. However, if you do, it also comes with a digital interactive display, making sure you won’t have any complications when it comes to the settings.

Overall, the Noritz NRC66DVNG looks to be a great product, and is great for any normal home. It comes with a 6.5 gallon per minute flow rate, however, this is much lower than other units, making it quite hard for it to cope up with high hot water demands.

  • Has two heat exchangers made of high quality copper and stainless steel
  • Has a 6 feet power cord for thermostat which is remotely controlled
  • Comes with a range of venting options
  • Low GPM

Rinnai RUR98iN, Condensing Tankless Water Heater

Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater

Our fourth product is another one from Rinnai, and it is the Rinnai RUR98iN. What you’ll immediately love about this unit is that it is relatively small, and has a very nice looking exterior. You’ll be able to place it easily in most places, without having to worry about the space.

With a 9.8 gallon per minute flow rate, you can rest assured that the Rinnai RUR98iN is one of the best in terms of providing you non-stop water throughout the house. As far as electric tankless water heaters go, this is also very easy to use and get around. This is especially because of the remote control interface, allowing you to make necessary adjustments from anywhere. You won’t have to run to the bathroom or under the sink to make any changes at any point.

Overall, the Rinnai RUR98iN is a great condensing water heater, and we definitely think it would fit in anyone’s home. It even comes with innovative technology built into it, to ensure the water flow stays consistent without leaving any lacking. The one drawback it has, is that this unit is a bit heavy in terms of its size.

  • Can use 1/2 inch gas line
  • 9.8 GPM allows for it to be very efficient for large homes
  • Comes with two heat exchangers
  • Energy rating up to 0.96
  • A bit heavier than most water heaters

Rheem RTGH 84DVLP, Condensing Tankless Water Heater

Rheem RTGH 84DVLP, Condensing Tankless Water Heater

The last one in our list of the 5 best condensing tankless water heaters, is the Rheem RTGH 84DVLP. This one comes in as one of the best choices for people with little children, when they want to make sure of that extra bit of safety. This is because this unit comes equipped with a foil on the outside to ensure the exterior will always remain cool, despite the heat inside.

Another great thing about its precautions, is its readiness to tackle colder climates. It comes built in with safeguards to ensure that the water heater can maintain its usefulness even if the environment and the incoming water is very cold. Thus, this is definitely a great choice for water heaters, if you’re in need of extra safety, or you live in colder climates. It is also a very environmentally friendly water heater, as it has a low NOx emission.

Overall, the Rheem RTGH 84DVLP is definitely one to look into, and it can serve you very well. It also comes with remote control settings, so you can adjust whatever you need from a distance. You won’t have to run to it all the time. This comes in handy, because this unit isn’t the best looking, or the smallest one out there.

  • Comes with additional safety for children
  • Comes with 120V power cord
  • Has a builtin electric blower
  • Very effective freeze protection up to -30 degrees fahrenheit
  • Can be used up til 9800+ feet above sea level
  • Isn’t the best looking and is quite large

Factors To Consider When Choosing A Condensing Water Heater

There’s various types of water heaters out there, each with their own set of requirements for you to look into when picking one out. When it comes to condensing water heaters, how do you do that? Well, let’s look into these factors and make sure you get the best one for your hot water needs.

Size and Weight

While this may not be the most significant factor when it comes to choosing a water heater, it still comes pretty high on the list. Considering you’ll want a good condensing water heater, you’ll want to ensure it’s tucked away neatly and out of reach. Otherwise, it could be dangerous if you have kids, or even a bad look to your home. So, it’s best to make sure you get a condensing water heater that is small and compact.

Tank or Tankless?

Our whole article has been based around tankless condensing water heater units. This is mainly because we think the tankless variant is much more feasible and easier to maintain in the long run. With a tank unit, you have to make sure to clean the tank twice a year, and there can be tons of other issues, including a large bill as well. With tankless units, you end up saving money in the long run, and the maintenance is easier. You also take much less space with tankless units.

Flow Rate

For every natural gas tankless water heater we have showcased to you, we believe their flow rate is good enough to maintain a large house for a full sized family. Whenever you’re choosing your gas tankless water heaters, you need to make sure they have a high enough flow rate, so that you can drive hot water throughout the entire home. A sink takes approximately 1.5 GPM (gallons per minute), and a shower takes approximately 2.1 GPM (gallons per minute). So, do ensure that you have some form of calculation ready when you’re going through these water heater reviews.

NOx Emissions

A gas water heater tends to release Nitrogen Oxide, and this is a very common gas in our environment. However, this tends to affect our atmosphere negatively, and a good trait to look out for in your tankless gas water heater is it needs to have a lower NOx emission. This will  be a lot better for the environment, and it doesn’t help to get one that’s friendly for it. With how much condensing water heaters have progressed throughout the years, you’ll find many to have low emissions and have great energy efficiency.

You can watch the proper installation process of a Rinnai Condensing Tankless Water Heater

Video Credit: The Rinnai Guy


Q. What is the best condensing tankless water heater?

In our opinion, the Takagi TH3DVN is the best condensing tankless water heater out there. It’s easy to install and can run hot water for large houses with ease, while having good environmental benefits.

Q. What brand of tankless water heater is best?

There isn’t one best brand, but brands like Rinnai, Takagi, Rheem and many others have various models on the market that are reliable.

Q. Are condensing water heaters worth it?

Condensing water heaters are very efficient, and will save you on water heating bills in the long run. It’s even better when it comes to tank versions, as condensing types will have higher first hour rating than the conventional type of water heater with the same capacity.

The Takeaway

A lot goes into the thought process of acquiring a natural gas tankless water heater, but we hope our article on the best condensing tankless water heater, has made you come to your final decision on which to get. Efficiency is a very important thing when you’re acquiring one, and that doesn’t just mean the heater being energy efficient. An energy efficient heater will save you a lot of effort with it’s digital interface, and also by its mechanisms. However, you also need to make sure you have the right flow rate (gallons per minute) to ensure your entire home can run efficiently. The whole list of water heater reviews was dedicated to ensure you manage to find the perfect one, and we hope you will!

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