Welcome to our article on the best condensing tankless water heaters on the market right now. So many people out there are tired of the conventional heaters being inefficient and costly to run and as a result, the leading brands have created a range of condensing tankless water heaters that operate far more efficiently and effectively by reducing wastage.

Contents

What is a Condensing Tankless Water Heater?

Our Recommended Picks
Best Condensing Tankless Water Heaters Comparison chart
Frequently asked questions
Conclusions

What is a Condensing Tankless Water Heater?

Condensing tankless water heaters work in a very similar way as conventional tankless water heaters. However, the majority of these conventional models are far less energy efficient, wasting a large amount of gas and heat energy.

Manufacturers have turned to utilising condensing technology in their tankless heaters. Exchangers are the primary elements in this process, contributing to capturing wasted gas and as a result, delivering more efficient results. You could save as much as 98% of your energy per month with the right heaters and many commercial tankless water heaters operate with condensing technology.

Our Recommended Picks

Best Overall

Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU

Best Value

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, small, Gray

Most Premium

Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater, 9.8 Max

Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, small, Gray

Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater, 9.8 Max

165 Reviews

38 Reviews

Check Price

Best Overall

Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU

165 Reviews

Check Price

Best Value

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, small, Gray

Check Price

Most Premium

Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater, 9.8 Max

38 Reviews

Check Price

Best Condensing Tankless Water Heaters Comparison chart

Best Choice

Runner-up

Noritz NRC66DVNG Indoor Condensing Direct Tankless Hot Water Heater, 6.6 GPM - Natural Gas

Also Good

Bosch C 1210 ES NG 225,000 BTU Natural Gas Indoor Condensing Tankless Water Heater

Also Good

EZ Ultra HE Propane (LPG) Gas Indoor Condensing Tankless Water Heater - Digital Display - Whole Home

Name

Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU

Noritz NRC66DVNG Indoor Condensing Direct Tankless Hot Water Heater, 6.6 GPM - Natural Gas

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, small, Gray

Bosch C 1210 ES NG 225,000 BTU Natural Gas Indoor Condensing Tankless Water Heater

EZ Ultra HE Propane (LPG) Gas Indoor Condensing Tankless Water Heater - Digital Display - Whole Home

Our Rating

4.9 / 5

4.8 / 5

4.7 / 5

Amazon Rating

Number of Reviews

165 Reviews

11 Reviews

Check Price

Best Choice

Name

Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU

Our Rating

4.9 / 5

Amazon Rating

Number of Reviews

165 Reviews

Check Price

Runner-up

Name

Noritz NRC66DVNG Indoor Condensing Direct Tankless Hot Water Heater, 6.6 GPM - Natural Gas

Our Rating

4.9 / 5

Amazon Rating

Number of Reviews

Check Price

Also Good

Name

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, small, Gray

Our Rating

4.8 / 5

Amazon Rating

Number of Reviews

Check Price

Also Good

Name

Bosch C 1210 ES NG 225,000 BTU Natural Gas Indoor Condensing Tankless Water Heater

Our Rating

4.8 / 5

Amazon Rating

Number of Reviews

Check Price

Also Good

Name

EZ Ultra HE Propane (LPG) Gas Indoor Condensing Tankless Water Heater - Digital Display - Whole Home

Our Rating

4.7 / 5

Amazon Rating

Number of Reviews

11 Reviews

Check Price

Rinnai RU98EN 9.8 GPM Outdoor Ultra-NOx Condensing Tankless Natural Gas Water Heater

Rinnai CU199eN Natural Gas Condensing Tankless Hot Water Heater, 11 GPM

Rinnai RU199eN Natural Gas Condensing Tankless Hot Water Heater, 11 GPM

Rinnai RL75iN Natural Gas Tankless Hot Water Heater, 7.5 GPM

Name

Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater, 9.8 Max

Rinnai RU98EN 9.8 GPM Outdoor Ultra-NOx Condensing Tankless Natural Gas Water Heater

Rinnai CU199eN Natural Gas Condensing Tankless Hot Water Heater, 11 GPM

Rinnai RU199eN Natural Gas Condensing Tankless Hot Water Heater, 11 GPM

Rinnai RL75iN Natural Gas Tankless Hot Water Heater, 7.5 GPM

Our Rating

4.7 / 5

4.5 / 5

Amazon Rating

Number of Reviews

38 Reviews

Check Price

Name

Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater, 9.8 Max

Our Rating

4.7 / 5

Amazon Rating

Number of Reviews

38 Reviews

Check Price

Name

Rinnai RU98EN 9.8 GPM Outdoor Ultra-NOx Condensing Tankless Natural Gas Water Heater

Our Rating

4.7 / 5

Amazon Rating

Number of Reviews

Check Price

Name

Rinnai CU199eN Natural Gas Condensing Tankless Hot Water Heater, 11 GPM

Our Rating

4.7 / 5

Amazon Rating

Number of Reviews

Check Price

Name

Rinnai RU199eN Natural Gas Condensing Tankless Hot Water Heater, 11 GPM

Our Rating

4.7 / 5

Amazon Rating

Number of Reviews

Check Price

Name

Rinnai RL75iN Natural Gas Tankless Hot Water Heater, 7.5 GPM

Our Rating

4.5 / 5

Amazon Rating

Number of Reviews

Check Price

Top 10 Best Condensing Tankless Water Heater

We have listed below, the 10 very best condensing tankless water heaters on the market right now, along with the key information we believe you need to make an informed buying decision. That includes key features and benefits, as well as the main pros and cons for each. As always, make sure you think about your individual requirements such as space, energy requirements, and budget before shortlisting the most suitable tankless water heater and then buying it.

1. Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU

First on our list is the Takagi condensing tankless water heater. This high-efficiency natural gas model is designed to be installed indoors and offers on-demand hot water whenever you need it. It claims to have ultra-low NOx emissions which offer peace of mind when installing anything like this. It will achieve 10-GPM and has a rating of 199,000 BTU

It is a compact, space-saving system that will not only save you money on your energy bills but space too. Its dimensions are 11.25 x 17.75 x 24.88 inches. It has computerized safety features, surge protection, freeze protection and overheat protection. It is important to note that there is no pilot light to worry about which makes life easier and the primary heat exchanger uses a commercial-grade copper alloy that helps transfer heat more than 25 times better than stainless steel.

Pros	Cons
A high-efficiency natural gas indoor tankless water heater You will get 10-gallons per minute with this water heater and improved efficiency thanks to the commercial-grade copper alloy The safety features of this tankless water heater include surge and freeze protection.	The 10-GPM may be more than required so do your research prior to buying it as you may be able to save money

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2. Noritz NRC66DVNG Indoor Condensing Direct Tankless Hot Water Heater, 6.6 GPM – Natural Gas

The Noritz NRC66DV has an advanced heat exchanger design with a built-in controller. You will get a flow rate of up to 6.5 gallons per minute, which is one of the best flow rates in this category of tankless hot water heaters. You also have a lot of options when it comes to ventilation including using Schedule 40 PVC Pipe and Fitting.

If you’re looking for an endless supply of hot water from an energy-efficient system then you can’t go too far wrong with a water heater like this. It is both highly efficient and has a low NOx rate, the perfect partnership for those wanting to reduce their bills but stay safe at all times. This tankless water heater will come with a 6-foot power cord and a remote thermostat but do note that it doesn’t necessarily come with everything required for installation including a valve kit so do your research to make sure you have everything required before purchasing. The dimensions of this model are 6.7 x 13.8 x 23.6 inches.

Pros	Cons
An efficient indoor condensing direct tankless hot water heater It will deliver 6.6GPM It comes with a remote thermostat for added convenience	The description suggest it doesn’t include everything required for installation (for example the valve kit), so make sure you check what is required before purchasing

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3. Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, small, Gray

Rheem is one of the industry-leading manufacturers and if you choose one of their products, then you can live safely in the knowledge that you have chosen an electric tankless water heater that will do the job! With dimensions of 18.25 x 3.5 x 14.5 inches, it is compact enough to fit in almost any space which is perfect for smaller properties.

Its durable copper immersion heating elements will deliver a flow rate of up to 4.4GPM, making it perfect for smaller flats and households, with installation being incredibly simple compared to more complex water heaters. It has an external digital thermostat control, with an LED display that shows you exactly what the settings are and what you have changed them to. This tankless water heater has an advanced self-modulation feature that will adjust power to meet the household’s demand for hot water, so you will never be without hot water when you need it most.

Pros	Cons
A highly efficient electric tankless water heater that will deliver a flow rate of up to 4.4GPM You will get an LED display to see what the settings are and the simple dial makes it easy to change when required. It also comes with a self-modulation feature to adjust the power according to household requirements.	At 4.4GPM it is one of the smaller water heaters on our list so make sure it will be powerful enough for your household requirements

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4. Bosch C 1210 ES NG 225,000 BTU Natural Gas Indoor Condensing Tankless Water Heater

You will most probably know all about Bosch and their tankless water heaters are fantastic. The C 1210 ES condensing tankless water heater is one of their highest performing, natural gas indoor models. With a rating of 225,000 BTU, it is designed for residential properties and will deliver a flow rate of up to 12.1GPM which makes it one of the most powerful on the list and great for larger properties.

The condensing technology captures heat from the exhaust gas and then uses it to preheat incoming cold water. This process increases efficiency and ends up reducing emissions, resulting in low enough NOx emissions to make you feel safe at home. You can choose to vent this tankless water heater via a 3 or 4-inch PVC vent pipe and it comes with built-in freeze protection as well as a water filter that can be accessed externally. The dimensions of this water heater are 17.9 x 11.25 x 30.5 inches which makes it larger than some others on the list.

Pros	Cons
One of the most powerful water heaters on the list with a flow rate of up to 12.1GPM Its condensing technology takes heat from the exhaust gas and uses it to preheat the incoming hold water You get built-in freeze protection and low NOx emissions for added safety	It is one of the largest sized water heater systems on our list and this is reflected in the price, so it may be too big or too powerful for some smaller households

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5. EZ Ultra HE Propane (LPG) Gas Indoor Condensing Tankless Water Heater – Digital Display – Whole Home

The EZ Ultra HE Propane condensing tankless water heater is an indoor water heater designed to heat up a whole home. With a capacity of up to 3.4GPM at 45 degrees Fahrenheit rise in ambient temperature, it is more focused on smaller properties but will still do a great job for many customers out there.

When you install this unit, it comes with the stainless steel horizontal vent pipe you need and it can either be vented horizontally or vertically using 2″ solid core Schedule 40 PVC/CPVC, which is easy to get. You should also note that it comes with a backdraft prevention device for added security and efficiency. Its dimensions are 27 x 14.5 x 6.5 inches which put it somewhere in the middle in terms of size but should fit well into most properties. Just make sure to check where the ventilation needs to go before buying it.

Pros	Cons
This tankless water heater can be vented either horizontally or vertically depending on space requirements It has a capacity of up to 3.4GPM at a 45 degrees Fahrenheit rise in ambient temperature It comes with a back-draft prevention device and stainless-steel horizontal vent pipe	A lower flow rate than many of the water heaters on our list so be careful to check if it will cover your entire house

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6. Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater, 9.8 Max

Rinnai’s Ultra Series condensing indoor natural gas tankless water heater offers real bang for its buck, with a flow rate of up to 9.8GPM. Taking up about the same about of space as a small suitcase, it really does deliver on the idea of maximum output, minimum space.

The innovative technology in this water heater delivers an endless supply of hot water but you need to make sure to check the installation location provides you with the gas line and ventilation options required. You get more venting options out of the box with this water heating, offering both concentric and PVC. The technology Rinnai uses includes dual heat exchanges that deliver maximum efficiency, up to a .96 factor. It is also wifi capable, an impressive bonus for those who want that extra control ability. The dimensions of this water heater are 12.5 x 10 x 26 inches.

Pros	Cons
The Rinnai Ultra series water heater will deliver a flow rate of up to 9.8GPM It uses dual heat exchanges to deliver maximum efficiency, up to a .96 factor The dimensions of this model are 12.5 x 10 x 26 inches, making it a powerful unit that takes up minimal space	It is one of the most powerful systems and this is reflected in the price. Some smaller flats or households may be able to go for a cheaper alternative

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7. Rinnai RU98EN 9.8 GPM Outdoor Ultra-NOx Condensing Tankless Natural Gas Water Heater

This Rinnai tankless water heater is an outdoor model but still delivers up to 9.8GPM, which is enough for most medium to large-sized households. It is an ultra-efficient model with a max BTU of 199,000, meeting both the California and Texas NOx emissions standards.

The max energy factor for this water heater is .93 and it will deliver a thermal efficiency of up to 95%. These kinds of figures make you realise just how much more efficient and cost-effect these water heaters are compared to traditional systems. It is compatible with the full range of Rinnai digital controllers and you get a 12-year warranty on the heat exchanger, as well as 5-year parts and 1-year labor. With dimensions of 18.5 x 10.7 x 26.4 inches, it doesn’t take up too much space outside but it is best to inspect the location where it will be delivered to make sure the connectors are suitable.

Pros	Cons
An ultra-efficient outdoor tankless water heater that delivers a flow rate of up to 9.8GPM It has a maximum energy factor of 0.93 and a thermal efficiency of up to 95% It is compatible with the full range of Rinnai digital controllers	Smaller households may prefer one of the smaller indoor tankless water heaters found on our list

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8. Rinnai CU199eN Natural Gas Condensing Tankless Hot Water Heater, 11 GPM

At an impressive 11GPM flow rate, this natural gas condensing tankless hot water heater delivers more than almost any other on our list. This makes it the perfect choice for larger households, with greater demands for hot water and no desire to have to wait around for it.

Whilst it is larger than other indoor models, at 22.05 x 14.76 x 33.86 inches it is still an incredibly efficient and space-saving unit. It will conserve energy by only heating up when necessary and you can choose from a range of venting options to allow flexibility in the installation process. The circ-logic technology within this water heater allows for recirculation patterns that coincide with your household habits and you can use Wi-Fi monitoring to ensure hot water is delivered on-demand. Like many other systems on our list, it is expected to last for many years and you get an 8-year warranty on the heat exchanger, 5-year parts, and 1-year labor.

Pros	Cons
A highly effective and powerful water heater with a flow rate of up to 11GPM It comes with different venting options to allow flexibility in the installation process You can use Wi-Fi monitoring to ensure hot water is delivered on demand	The most powerful system on our list and not needed for smaller households

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9. Rinnai RU199eN Natural Gas Condensing Tankless Hot Water Heater, 11 GPM

Almost identical in every way to the product above but this is the outdoor version!

Pros	Cons
A highly effective and powerful outdoor water heater with a flow rate of up to 11GPM It comes with different venting options to allow flexibility in the installation process You can use Wi-Fi monitoring to ensure hot water is delivered on demand	The most powerful system on our list and not needed for smaller households

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10. Rinnai RL75iN Natural Gas Tankless Hot Water Heater, 7.5 GPM

This Rinnai RL75iN natural gas tankless hot water heater is a smaller version of the systems above, yet still has some of the fantastic features and extras that make the Rinnai series of water heaters stand out from the crowd.

Its flow rate of 7.5GPM makes it perfect for the average household and some more demanding smaller households. This helps save on space and expense when compared to the high-performing 11GPM systems above. It will conserve energy by only heating when required, yet again saving you money on your energy bills and helping the environment by being more efficient. The circ-logic technology within this water heater allows for recirculation patterns that coincide with your household habits and you can use Wi-Fi monitoring to ensure hot water is delivered on-demand. The dimensions of this water heater are 17.5 x 13 x 31 inches.

Pros	Cons
One of the many fantastic Rinnai tankless water heaters on the market right now, with this one producing a flow rate of 7.5GPM It comes with circ-logic technology to allow for recirculation patterns that coincide with your household habits You can use Wi-Fi monitoring to ensure hot water when you need it	At 7.5GPM it is less powerful than the bigger 11GPM Rinnai systems whilst saving some money. For many households, the larger system may provide greater reliability and heating.

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Frequently asked questions

We’ve put together some of the most frequently asked questions from customers, along with answers to help make the entire purchasing process easier.

What size tankless water heater do I need?

This very much depends on the size of your household and hot water demands. You will see that the majority of tankless water heaters have a flow rate of between 5GPM and 11GPM. The 5-7GPM tankless water heaters are designed for smaller to medium-sized households so if you have a big family or a large property, it is advisable to go for a larger option.

However, it is important to note that this isn’t the only consideration to have and it is important to understand your household requirements, as well as the efficiency of the system and where it is going to be installed. You may need to install it outside, which limits the choice, or perhaps you want an electric one installed inside which again narrows down your choices of the best condensing tankless water heater systems for you.

Are condensing tankless water heaters better than others?

There are some fantastic tankless water heater systems out there but thanks to the technology within a condensing tankless water heater, you really do save money and help to protect the environment. The condensing technology makes them far more efficient than traditional tankless water heater systems and we have talked a little about this at the top of the article.

With greater awareness about the impact we have on the planet, as well as a focus on saving money any of these condensing tankless water heater systems can really transform your home.

What are the benefits of a condensing tankless water heater?

Just a few of the fantastic benefits of choosing a condensing tankless water heater are as follows:

It can save as much more than 90% energy compared to traditional systems
They often have lower operating costs and this leads to cheaper heating bills for your household
A condensing tankless water heater is a good choice for more demanding properties and commercial properties
They are more environmentally friendly thanks to lowering CO2 and NOx emissions.

Conclusions

Thank you for taking the time to read this article on the best condensing tankless water heater systems on the market right now. Once you’ve read through the details for each one, you should be in a much better position to make an informed decision on the best tankless water heater system for your household.

Please take a moment to explore the rest of our website for articles on the best water filters, heaters, humidifiers, and coolers, as well as other useful information.

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