Holds a Master’s degree in Engineering and is keen on her own home’s climate. Sometimes we think that Carolina owns every single product she writes about – that’s how profound and insightful her reviews always are.
For 8 years, Richard had been working as an HVAC specialist and AC unit installer since his student years. Now, he’s our main consultant on every technical aspect that may arise during our tests and research.
Last updated: May 06, 2022
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If you own a home, then you know how expensive it can be to heat your water. Water heating costs usually add up to about 20% of your home’s overall heating bill, unless you get the best gas tankless water heater you can. These models are incredibly energy-efficient and also have the ability to provide hot water at all times, without any wait time.
As you can imagine, there are lots of different features that you need to consider when you are looking for the best residential tankless gas water heater. For our listing, we first looked into the overall dimensions, since this will determine how large of a space you need to install it correctly. Next, we checked into the different fuel sources available, as you will need to select from either natural gas or propane.
Finally, we looked at the BTUs and flow rate for each model, since this will give you the info you need to find the right model for the size of your family and your home.
We have spent tens of hours reading through hundreds of user reviews to find the best models on the market today. This research has allowed us to not only put together a comprehensive list but also complete detailed reviews of each model. Of course, if you are not ready to find a model quite yet, be sure to read through our in-depth buying guide, which will give you all the information you need to find the right model for your needs.
Warranty: 12-year limited on heat exchanger; 5-year on parts; 1-year on labor
More features: ultra-low NOx emissions; concentric or PVC venting option
If you are in the market for the best overall gas tankless water heater for your home, then this just might be your best bet. The first hint that this is such an outstanding model is how long of a warranty that the company offers for it. If you do decide to purchase this unit, you can rest assured that most of the parts will be covered for up to five years, while the heat exchanger will be covered for 12 years total. This warranty helps to make an already outstanding heater that much better.
Something else that helps to set this model apart from the crowd is its amazingly high BTU amount. Even if you have a large home with multiple bathrooms, sinks, tubs, and showers, you shouldn’t have any issue keeping the water nice and hot. This heater can crank out about 199,000 BTUs and has a very high 9.8 GPM flow rate too. These two factors make this a workhorse of a heater that is up to the challenge, even if you have a larger home and a big family.
The only real issue with this heater is that it is, unfortunately, quite difficult to install. Even though it gives you the option of the venting materials you can use, it should probably only be installed by a professional. Thankfully, once this heater is installed, you will get to reap the benefits of its efficient design. You can also rest assured that it is very safe to operate, since it has an ultra-low emissions rating, making it a great option for anyone concerned with safety.
Warranty: 15-year limited on the heat exchanger; 5-year on parts
More features: 4-Inch category III stainless steel venting required
Years ago, the heating fuel of choice for most folks was undoubtedly oil. It wasn’t extremely efficient, but it certainly was cheap. Nowadays, oil is giving way to a much more efficient, cleaner, and, amazingly, cheaper fuel in natural gas. As such, it is only natural to want to use this wonderful fuel for your water heater. If that is the case for you, then this is a great option, since it is by far the best natural gas tankless water heater on the market today.
As with the previous model, you can tell right off the bat that the company is going to stand behind this product, thanks to the extremely long warranty. Not only are all of the parts covered for five years, but the heat exchanger is also covered for fifteen years after the date of purchase, which is among the longest available.
Tankless water heaters are usually extremely compact in comparison to standard models, but this unit is compact even for a tankless model. This compact design makes it a great option for anyone that is looking to save a bit of space in their basement.
Even though this is a relatively small unit, it is still able to produce plenty of BTUs and has a pretty high flowrate. Though it probably won’t be quite enough for a larger home, this unit would be perfectly serviceable in a smaller or medium-sized home, even if there is more than one shower running at a time.
If you do decide to purchase this unit, you need to keep in mind that it doesn’t come with everything necessary to install it correctly. The ventilation piping will need to be purchased separately, which is going to add to the overall purchase price, so keep this in mind before you make your final decision.
Why did it make our list?
High max BTUs
What is not ideal about it?
Doesn’t come with everything needed for installation
Warranty: 12-year limited on heat exchanger; 5-year on parts; 1-year on labor
More features: digital display shows temperature setting and maintenance codes
If you are lucky enough to have a larger home that has more than one bathroom, then you are going to need a bigger water heater. Otherwise, you won’t ever be able to keep up with the hot water demands of your family. If that is the case for you, then this just might be the right unit to suit your needs.
To start off with, this unit is built very solidly. It is able to produce up to 199,000 BTUs, making it perfect for a family or home with high hot water usage demands. Not only that, but it also features extremely high flowrates. This unit tops out around 9.5 gallons per minute, which should be more than enough for any home, even if your family is going to be using more than one shower at a time.
Though this water heater is definitely one of the bigger models on the market, it is still more compact than a standard heater with a tank. Plus, its larger design helps to make it a much more durable option than smaller heaters. It also comes with a nice long warranty, which is a testament to the quality of the overall design of this unit.
This is also one of the easiest to set water heaters you can buy. The controls and display of this unit are very easy to use, which makes it very simple to set the water temperature that is ideal for your home.
Warranty: 12-year limited on heat exchanger; 5-year on parts
More features: remote thermostat and 6′ power cord included
Let’s face it, getting a new water heater is expensive, even if you get a model that uses a tank. Getting a tankless model is even more expensive since they are much more technologically sophisticated. This high upfront cost can make it difficult for someone on a tighter budget to afford a tankless unit. Luckily, this model is a good option for anyone that is looking to save a bit of money, while still getting a high-quality tankless water heater.
First off, this is a very compact model, which makes it a great option for anyone that is not only looking to save money but also as much space as possible. It is also very easy to install pretty much anywhere, thanks to its long power cord. This model also comes with a remote thermostat, which makes adjusting the temperature of the water a very easy process.
What is really surprising, especially considering how budget-friendly this model is, is how high its maximum BTUs and flow rate are. Even though this is definitely a cheaper model, it is still powerful enough to easily heat enough water for a small to medium-sized home that has more than one bathroom. This powerful design, obviously, helps to make this a great value.
Of course, there is one thing that you need to keep in mind with this model. It has a very high gallons per minute demand rate that needs to be met before it turns on. Basically, what this means is that you always need to open your faucet or shower to its highest pressure for this unit to start heating water. If you only turn the water on a little bit, it will not turn on, which would result in the water remaining cold.
More features: LCD temperature display; child locking technology
If you are in the market for a smaller sized tankless water heater, then this just might be the right option for you. Even by the minuscule standards set by most tankless models, this is still a very slim and compact unit. This compact design makes it a wonderful option for anyone that lives in a smaller home where storage space is at a premium.
Of course, the compact design of this model does limit its effectiveness somewhat. This natural gas water heater isn’t capable of reaching terribly high BTUs and has a relatively slow flow rate when compared to its competitors. However, if you are thinking of getting this model to use in a smaller home with only one or two bathrooms, that shouldn’t be that big of a problem.
This unit also has the benefit of being extremely simple to install. Since it is so small, it practically fits anywhere, and, even if you have an older heating system in place now, shouldn’t require too much retrofitting. This easy installation should help to save a bit of money as well.
Something else that makes this an attractive option are its easy-to-use controls and simple-to-read display. Not only are the controls easy to use, but they also utilize child locking technology, which is a great safety feature if you have any little ones at home. Basically, this feature prevents anyone that doesn’t know the proper code from changing the settings, which is always a plus when there are children around.
What stands out?
Child safety lock
Easy to install
What cons did we manage to find?
Low flow rate and maximum BTUs when compared to others
As you may have noticed, most gas water heaters are meant to be used indoors. This is mostly due to the fact that they have much higher gas needs, and, therefore, should not be moved around or put out in the elements. This model, on the other hand, is built to be portable and to be used outside.
Something else that helps to make this model even more versatile is that it can be used with either natural gas or propane. Of course, since this is not meant to be permanently installed to heat water for a whole house, you need to have those fuels available in an easy access to connect to tank.
One of the best features for this particular tankless heater is that it comes with a showerhead attached to it. Of course, you can also hook it up to a more permanent shower fixture if you so choose. This pre-attached shower head helps to make this a great option for camping, however, since you can hook it up to any water source as long as you have fuel along with you.
While the compact and versatile design of this unit helps to make it very energy efficient, there is one big issue that you will need to keep in mind. Since this is such a small and portable water heater, it does not have a very high flowrate. It can only heat about 2.64 gallons per minute, which does limit its effectiveness a bit. Of course, if you are only using this model for an outdoor shower on its own, this shouldn’t be too big of a deal.
What are its best features?
Can be used indoors and outdoors
Easy to install
Great for camping
Can be used with propane or natural gas
What could be improved?
Very low flowrate
Things to Consider
In this section, we will go through everything that you need to know to find the best gas tankless water heater for your needs. We have also taken the time to answer several frequently asked questions, so be sure to read through those if you have any more questions.
Benefits of having a gas tankless water heater
When it comes to getting a new water heater, you can either get a standard model that comes with a tank or a tankless model. While tankless models are a bit more expensive upfront, they offer a ton of benefits over standard models, such as:
Energy-efficient – One of the biggest issues with a standard gas water heater is that it comes with a tank, which is used to store the hot water. Whenever you use hot water, the tank will empty, which is when the heater kicks in to heat the entire tank again. This is extremely inefficient. A tankless model, on the other hand, doesn’t need to heat up any water that you aren’t using. Instead, it heats the water as you need it, which is much more energy-efficient.
Long lifespan – Since a tankless water heater doesn’t need to work nearly as hard as a standard model, they are much more likely to last for a good long time. In fact, tankless models usually will last, on average, 5-10 years longer than a standard water heater.
Less storage space – Another big benefit that the lack of a water tank provides you is that you need a lot less space to store your water heater. Since tankless models are much more compact than standard models, they can fit into smaller basements or tighter spaces, they can even surve as under sink water heaters.
Unlimited hot water –The final and, perhaps, most important benefit that you will get to enjoy when you select a tankless water heater is that you will never run out of hot water. Since these amazing heaters heat the water as you need it, it is impossible for you to run out of water, which is very different than with a standard model, which will eventually run out of hot water.
Features to consider while choosing a gas tankless water heater
As you can imagine, there are several things that you need to keep in mind when you are looking for a tankless gas water heater. In this section, we will go through everything that you need to know to find the right model for your home.
Which fuel is required
The first thing that you want to check into with each tankless water heater is the type of fuel that it requires. When it comes to fueling your new water heater, you can choose from a heater that is set up to use propane, natural gas, or both. Both of these fuels are relatively inexpensive, though natural gas is a bit cheaper. The more important factor in the type of fuel you pick for your new heater is the type of fuel that your home is set up to use.
While it is always possible to switch between fuel types, this is going to be an expensive process, so you might want to just stick with what you already have. Or if you could foresee switching fuels sometime down the road, you might want to just get a heater that can handle both fuels, like the Rinnai RUC98iN. Unlike electric tankless water heater, these devices need to be ‘charged’ in time.
The heating power of each of these tankless water heaters is measured in BTUs. These units indicate how much heat a unit can put out. If you have a lot of family members, then you are going to want to look for a unit that has a lot of BTUs, like the Rheem RTGH-95DVLN. That way, you can help to guarantee that you will have enough hot water to go around, regardless of the demand for it.
Of course, the higher the BTUs, the more expensive the model is going to be upfront. If you are looking to save a bit of money an don’t mind the lower heat output, you can probably get by with a model like the Camplux BW264, which is still a very efficient heater, even though it has a much lower BTU output.
Gallons per minute
The next thing that you will need to consider after you have your BTUs figured out is the flowrate that you need for your home. This rate is usually communicated in gallons per minute. This number will tell you how many gallons your new heater will be able to keep nice and toasty for you each minute. If you live in an area with lower pressure, then you can probably get by with a lower flow rated model, such as the Eccotemp i12-NG.
Of course, if you have a home with higher water pressure or your family uses a ton of water, then you will need to get a model with a higher gallons per minute rating. Otherwise, you could still end up with less hot water than you want, even though you have a tankless model. The Rheem RTGH-95DVLN is a great option in this instance.
Something else that you will want to take into account is the temperature range that your new heater will be able to produce for you. Thankfully, no matter which heater you select, you are going to be guaranteed ample amounts of hot water, but just how hot that water needs to be is up to your personal preference.
Obviously, the hotter the water, the more fuel you are going to consume, which will also cause your energy bills to go up. No matter the heat range that you decide upon, you need to make sure to get a heater that is easy to adjust, so that you can get the temperature exactly where you want it to be.
When it comes to a tankless water heater, no matter what model you select, you are going to save a ton of space over a model that uses a tank. That being said, not all of them are as slim or space saving as you might like, which is a pretty big factor if you have a smaller basement, to begin with. If you are looking for the slimmest model possible, then the Takagi T-KJr2-IN-NG is a great option. This model is especially small from front to back, which makes it an exceptional unit when it comes to saving floor space.
One of the only disadvantages of getting a tankless water heater is that they cost a good bit of money upfront. While they more than make up for this by saving you money on operation costs, you definitely don’t want to spend any more money than you need to. That is why you need to make sure that you find a model that comes with a good warranty.
A warranty is very much like an insurance policy. Basically, it helps to cover you in case something goes wrong with your unit. A warranty will help alleviate the expenses that you need to pay out of pocket should any part of your new heater fail during normal use. Of course, you need to make sure that you read through the fine print as carefully as possible. Lots of companies will claim that they offer a long warranty, but actually, only cover a small list of repairs.
While water heaters are relatively straight-forward devices that don’t come with a ton of bells and whistles, it isn’t a bad idea to be on the lookout for a few extra features that will help to make the unit that much more effective. One such feature is a digital display and easy-to-use controls. These features will make adjusting the temperature a whole lot easier, as well as allowing you to see if your machine is working properly.
Something else to keep in mind is the type of ventilation that your new heater is going to require. To save time and money, it might be a good idea to get something along the lines of the Rinnai RUC98iN, which can be vented in several different ways.
Some tankless water heaters can be used outdoors, but not all of them. You need to be sure beforehand if the heater you are interested in can withstand the elements that it will be subjected to outside, so be sure to read all of the necessary information as carefully as possible.
The best gas tankless water heater is going to be more efficient than an electric model, mainly because gas is much cheaper as a source of heat than electricity. By getting a gas model, you can save yourself a lot of money on energy expenses throughout the year in comparison to if you were to get an electric tankless water heater.
Of all the different tankless water heaters that we looked into, the Rinnai RUC98iN is by far the best available. This heater can be used with either propane or natural gas, making it an extremely versatile unit. It is also capable of an impressively high BTU output and has a very high flow rate, which makes it a great option for any size home or family. We highly recommend that you check this model out!
Of course, if you are looking for the best natural gas tankless water heater, then the Takagi T-KJr2-IN-NG is the model you should look into. It is a very compact unit that also can pump out a high number of BTUs and is capable of a very high flow rate.
If you have a larger home, then the best gas tankless water heater for you is going to be the Rheem RTGH-95DVLN. While this unit is a bit on the bulky side, its amazingly high heating capacity and flow rate make it the perfect heater for larger home or bigger families.