Best Condensing Water Heaters of 2021

Want to save energy and money on a water heater? We’ve got you covered.

Looking for an even more energy-efficient way to heat up the water in your home? A condensing water heater may be just the answer.

After researching every corner of the internet, we’ve found what we believe are the 4 best condensing water heaters currently available on the market.

We’ve found a safe option, a good-looking one, an option for an exceedingly high flow rate, and a tiny one!

Our Top Picks

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Product Comparison Table

Product Image of the Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU
Highest Flow Rate
Takagi T-H3-DV-N
  • High flow rate at 10 GPM
  • Emits low amounts of NOx
  • Digital interface
Product Image of the Noritz NRC66DVNG Indoor Condensing Direct Tankless Hot Water Heater, 6.6 GPM - Natural Gas
Smallest Condensing Heater
Noritz NRC66DVNG
  • Small & lightweight
  • Remote controlled thermostat
  • 12-year warranty
Product Image of the Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater, 9.8 Max
Most Aesthetically Pleasing
Rinnai RUR98iN
  • Sleek metal exterior.
  • Remote interface
  • 12-year warranty
Product Image of the EZ Ultra HE Natural Gas Indoor Condensing Tankless Water Heater - Digital Display - Whole Home
Most Efficient
EZ Ultra HE
  • Versatile installation
  • Fully automatic
  • Works with low water pressure

What Are Condensing Water Heaters?

When water heats up, it produces water vapor. When this occurs, latent heat of vaporization — the energy used to convert a liquid into gas — is lost. However, in a condensing water heater, the latent heat of vaporization is recovered. This ensures that energy isn’t wasted but is utilized within the water heater.

In fact, condensing water heaters retain around 90 percent of the energy that may otherwise be lost in the process. This makes for an efficient means of heating the water in your home.

Condensing water heaters are fuelled using either gas or oil. However, our top four, which you’ll find below, all use gas.

How to Choose the Best Condensing Water Heater

Here are a couple of factors we think you should keep in mind before you make your purchase.

Tank or Tankless

Heaters with tanks are often found within the home, storing water ready for use. They’ll usually be hidden in a cupboard somewhere, away from the rest of the home.

Alternatively, tankless options require a little less space than tanks. These heat up water instantly within their mechanism.


It’s in the name really — a tank heater will store warm water, ready for use. They’re usually pretty cheap, easy to install, and will be found in most older houses.

However, these days, people are transferring to the tankless option. They’re a little more practical, particularly for larger families due to the limitless hot water they provide.

None of our options below come with a tank — tankless all the way. Heaters with tanks are becoming pretty obsolete these days. It’s no wonder we couldn’t find any to recommend, even after scouring the internet.


  • Cheaper


  • A finite amount of water.
  • Must keep water within them hot at all times, wasting energy.


Tankless water heaters take cold water from the water source of your home. They then heat this water instantly in the boiler and expel it through your taps or shower heads. This results in a continuous supply of hot water — particularly ideal for larger families.

Although they’re a little more expensive to install, they save a lot of energy. This is because they don’t have to maintain the heat of the water in the tank. So, despite the initial hefty cost, over time, they’ll certainly make up this money through energy-saving (1).


  • Instant water heating.
  • Unlimited water heating.
  • Take up less space than a tank heater.
  • Energy-saving.


  • More expensive than a tank heater.
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Digital or Remote

Some of our options for the best condensing water heaters will be operated via the tank itself. In other cases, the product can be operated using a thermostat. But what’s the difference?


Digital water heaters have an operating system on the machine. This requires you to actually go to the heater itself to sort out the settings.


  • Easy to use.


  • Not ideal for accessing if your heater is in a remote location or you have poor mobility.


These units have no buttons on the boiler itself. Instead, they are operated using a thermostat which you can mount in any room of the house.

An ideal location is in, or near, the kitchen. This makes it super easy to access, as it’s usually the most used room in the house.


  • Requires minimal effort to turn the water heater up or down.


  • It may require a little more installation than a digital water heater.
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Low NOx Emissions

This is a pretty common trait in condensing water heaters, and it’s a great trait at that. Nitrogen Oxide is a common waste matter from gas-operated machines. It is a poisonous gas known to contribute to the thinning of the ozone layer (2).

With current environmental concerns, it’s important to do everything we can to avoid exacerbating this problem. This is why we prefer low NOx emitting water heaters.

Small and Compact

Although this factor may not be as significant here as it is for portable water heaters, it’s still important. Most of us like to make sure everything has its rightful place in the home, and the water heater is no exception.

As such, we’ve chosen four small options that will be barely noticeable amongst your home decor.

High Flow Rate

The flow rate — the number of hot water sources that can be used at one time — is measured in gallons per minute or GPM. The higher the GPM, the more showers can be taken at one time. This alongside the dishwasher, washing machine, faucets, and the like!

In general, one sink uses around 1.5 GPM, and one shower uses around 2.1. So, every one of our options below is a winner in our eyes, as they all exceed 6.5 GPM. The larger your family, the higher a GPM we would recommend, so take your pick.

The Best Condensing Water Heaters of 2021

Here are 4 great condensing water heaters to consider.

1. Takagi T-H3-DV-N Condensing Tankless Water Heater

Highest Flow Rate

With its digital interface, the Takagi condensing water heater is super easy to use. Connect it to your gas mains pipe, and it’ll provide hot water for up to four showers in one go!

Takagi pride themselves on their ability to tailor their water heaters to your needs. This is why they produce various units in different sizes and flow rates to suit your requirements.

Why We Love It

High GPM

One of the best features of this water heater is its high flow rate. You can have more water appliances operating at one time than any other option on our list, without the risk of the water going cold.

This makes the Takagi water heater ideal for a larger family. Perhaps this would also make a great option for a student house, as they usually have more showers than the average home.

10 GPM equates to nearly five showers at one time! That’s pretty impressive. It ensures every water appliance in your house — showers, sinks, dishwashers, and the like — can be used all at once.

Emits Low Amounts of NOx

Anything with low NOx emissions is a bonus for us. This way, you’ll be reducing your carbon footprint — something everyone should get on board with in today’s world.

Digital Interface

Digital interfaces are becoming a lot more common for household goods. Everything from coffee machines to blenders is now digital. Water heaters are no different.

The Takagi water heater has a digital interface for ease of use. Even a novice can work one of these — no need for a technology whizz in the household.

Keep In Mind

Provides Less Hot Water in Colder Climates

In colder temperatures, the incoming groundwater temperature will naturally be cooler. The water entering into a tankless water heater will therefore be cooler. This allows for fewer warm water appliances to operate at one time.

So, before purchasing one of these Takagi water heaters, be sure the product suits your water needs. If you have a larger family needing multiple showers per day all year round, this is something to consider.

Additional Specs

Dimensions 11.2 x 17.8 x 24.9 inches
Weight 85 pounds
Flow Rate (Gallons Per Minute) 10 GPM
Input Type Gas operated
Digital or Remote? Digital
Indoor or Outdoor Use? Indoor only

2. Noritz NRC66DVNG Indoor Condensing Tankless Water Heater

Smallest Condensing Water Heater

The Noritz condensing water heater is another tankless option. It also provides an energy-saving mechanism with low NOx emissions. Want endless water for the whole family? You got it.

This product is ideal for anyone with limited space in their home. No need for the capacity of a usual tank boiler, as it can fit discreetly almost anywhere.

With its simple white design and small footprint, we really like how it looks.

Why We Love It

Small and Lightweight

This is another pretty small option, actually achieving the accolade for the smallest of our picks. You can stow this option away in any small area in the house, like a cupboard or smaller room. It’s pretty non-obtrusive and ideal for anyone concerned over aesthetics.

Remote Control

Most people will stow their water heater away in a location where it can’t be seen. If this is the case, a great way of managing it is through a remote interface.

Pair this unit with that technology, and you can control it from a wireless thermostat in any chosen room.

Long Warranty

What we particularly love about the Noritz water heater is the long warranty. It includes a 12-year warranty on the heat exchanger, five on parts, and one on labor. So, you’ll be covered for almost all eventualities, showing that the company takes pride and has faith in its product.

Keep In Mind

Disappointing Flow Rate

Despite promises that this heater has the highest flow rates on the market, this is not the case. It falls short, especially when compared to the other water heaters on our list. That said, it’s still a pretty high flow rate of 6.5 to 6.6 GPM, considering its tankless nature.

Additional Specs

Dimensions 6.7 x 13.8 x 23.6 inches
Weight 39 pounds
Flow Rate (Gallons Per Minute) 6.5 GPM
Input Type Gas operated
Digital or Remote? Remote
Indoor or Outdoor Use? Indoor

3. Rinnai RUR98iN Ultra Series Tankless Water Heater

Most Aesthetically Pleasing

The Rinnai water heater is another condensing water heater with a pretty extensive warranty. This shows us that the product is made to do the job and we can trust the company.

It also has a super sleek metal exterior. Although a little larger than some other options, this one should fit in nicely in any home. Once installed, tell it what to do using the remote interface — it’s as easy as that.

Why We Love It

Sleek and Aesthetically Pleasing

If you’re looking for a good-looking, sleek condensing water heater, then this one’s for you. It’s easy-to-use, relatively small, tankless, and has a high GPM. It’s not only pretty but practical too.

It’ll do the job you want it to while fitting seamlessly into your home decor.

Remote Use

We love a product that can also connect with a remote interface. Most people will mount the remote interface somewhere communal, like the kitchen or living area.

This way, there’s no need to run to the basement or wherever your water heater is stowed to change the temperature of your home. Instead, you can access your water heater from a more communal area — much less effort.

Extensive Warranty

We admire a product with a long warranty. Why? Well, it shows that the company has faith in its product.

Look at the long list of warranty extras to see how proud Rinnai is of this water heater. They include a limited 12-year warranty on the heat exchanger, five on parts, and one on labor. You can’t go wrong with that.

Keep In Mind


Despite the easy use, this unit is pretty heavy. So it may be a little more difficult to maneuver into your property than our others. That said, once it’s in, it’s in, so it shouldn’t cause you many issues after installation.

Additional Specs

Dimensions 12.5 x 10 x 26 inches
Weight 81.6 pounds
Flow Rate (Gallons Per Minute) 9.8 GPM
Input Type Gas operated
Digital or Remote? Remote
Indoor or Outdoor Use? Indoor only

4. EZ Ultra HE Condensing Tankless Water Heater

Most Efficient Condensing Water Heater

If efficiency is what you’re looking for, check out this water heater from EZ. It uses fantastic condensing technology which utilizes exhaust gas. This preheats incoming water to ensure maximum efficiency.

This heater eliminates much of your home’s stand-by energy to rule out loss. In turn, this saves you both energy and money.

It also uses high thermal efficiency plus awesome combustion performance. Overall, you’re getting more for your money with this purchase.

Why We Love It

Versatile Installation

You can install for horizontal or vertical venting. This may seem like a minor detail, but it can actually save you space since you can fit it in with your home’s specific design. Just use the two-inch solid chore schedule 40 PVC to install.

Fully Automatic

To use, simply turn on the water spigot or shower. Your hot water will be there in just a few moments. It even has fully automatic temperature modulation. So once you choose your temperature, the unit will regulate everything to maintain this. When you turn the tap off, the water heater will automatically stop heating.

Works With Low Water Pressure

Even if you have low water pressure at home, this can still work, and it can function on as little as eight PSI. Therefore, this is a good choice for people living at high altitudes as well as those using older pumping systems that maybe aren’t as powerful.

Keep In Mind

Not for Large Homes

This water heater is designed for two-bath homes only. If you have more than that, this isn’t going to be suitable.

Not Good for Quick Hand Washing

Because it does take a few moments to heat the water, it’s not suitable for 20-second hand washes. So you may find just using cold water is more suitable and efficient.

Additional Specs

Dimensions 27 x 14.5 x 6.5 inches
Weight 31 pounds
Flow Rate (Gallons Per Minute) 3.4 GPM
Input Type Gas operated
Digital or Remote? Digital
Indoor or Outdoor Use? Indoor

Condensing Water Heater Comparison Chart

Product Award Dimensions Weight Flow Rate Input Type Digital/ Remote Indoor/ Outdoor
Takagi T-H3-DV-N Highest Flow Rate 11.2″ x 17.8″ x 24.9″ 85 lbs 10 GPM Gas Digital Indoor
Noritz NRC66DVNG Smallest Heater 6.7″ x 13.8″ x 23.6″ 39 lbs 6.5 GPM Gas Remote Indoor
Rinnai RUR98iN Most Aesthetically Pleasing 12.5″ x 10″ x 26″ 81.6 lbs 9.8 GPM Gas Remote Indoor
EZ Ultra HE Most Efficient 27″ x 14.5″ x 6.5″ 31 lbs 3.4 GPM Gas Digital Indoor

Headshot of Peter Gray

About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.