Best Gas Tankless Water Heater in 2023

There are a wide variety of gas tankless water heaters currently available. With options like interior only varieties and portable units, it can be difficult finding the best gas tankless water heater for you. In our article, we’re going to be covering 10 of the best models available online. In addition, we will also have a buyer’s guide section that contains valuable information to help you with the buying process.

Best Gas Tankless Water Heater Comparison Table

Reviews of Gas Tankless Water Heaters

Bosch Greentherm C 1050 ES NG – The Best All-Around Natural Gas Water Heater

The Bosch Greentherm is the best and the most expensive unit on our list. It is durable, reliable and sophisticated. It provides a consistent flow of hot water and features an easy-to-access inlet for water and gas access to ensure more comfortable and convenient installing.

Also, if you need any in-depth technical details regarding the heater, you can access them via its mobile app. As with most other Bosch devices, this heater is extremely durable. With adequate maintenance, it can serve you for an entire decade without any drop in performance. Its control board is simple to use, and the orange display allows effortless temperature and programming reading.

This heater is one of the best in the area of thermal efficiency for it features a rating of 94%. It is heavier (86 lbs) and larger (11.2 x 17.9 x 30.5) than any other unit on our list, but if you have space and the money for it, then you should consider obtaining it. We also recommend it for commercial use due to its conservative gas and electricity consumption. The Bosch Greentherm C 1050 ES NG is also the most powerful unit on our list, featuring a flow rate of 10.5 GPM.

Rinnai RUC98iN – Best Natural Gas Tankless Water Heater For Commercial Use

The RUC98iN is one of the most expensive items on our list. However, it is also one of the best indoor heaters. Its advanced condensing technology allows excellent energy efficiency, with up to 0.96 energy factor. It is compact (10 x 18.5 x 26 in) but pretty heavy, weighing 82 pounds.

This natural gas tankless water heater has a 95% thermal efficiency and is intended for residential and commercial use. Business owners will love it for its energy-saving technology and the heat at up to 185° F. Those who plan to use it for commercial purpose, make sure that you also obtain the commercial temperature controller.

It is a bit slower on the heating, and you might experience a hot-water delay, but this also depends on your plumbing and where you install the heater. We highly suggest that you include the condensate control kit in your package to prevent any potential damage to your septic tank and water system. It isn’t imperative that you use the kit because the RUC98iN runs fine without it, but we still suggest it for the sake of safety and durability.

And in case you experience the dips in the water pressure, try cleaning the filters. If that doesn’t help with the pressure, flush the heater altogether. Whether you experience the issue with the pressure or not, flushing is recommended, at least once a year. Note that this heater features a recirculation system and that you can use it to have instant access to hot water.

Rinnai RL75iN – Best Natural Gas Tankless Water Heater For 3-Bathroom Homes

The RL75iN is a pretty pricey and powerful best, with a flow rate of 7.5 GPM. It features a classic Rinnai design; a compact build, easy to use control board and metallic finish to meet all decors. It comes with the included MC-91-1US Digital remote control. Moreover, it has an error indicator that provides safe and error-free use.

Its thermal efficiency is mediocre and is rated at 82%, which is way lower than the Rinnai RUC98iN 95%. Now, the thermal efficiency doesn’t substantially affect residential wallet, but it will business owners, who should probably avoid this unit.

Unlike your traditional tank heaters, this one uses up to 199,000 BTU’s per hour. So, to use this heater to its fullest, make sure that your gas supply line is compatible with it. Furthermore, we have to commend its energy-saving design. It is pretty high-tech, featuring a control board, a quiet and efficient combustion fan. It also has the electronic solenoid valves that give you more control over water and gas flow.

However, all these high-tech components require a lot of maintenance, so make sure that you flush it regularly. Also, you should be aware of the fact that it might be tricky to find an adequate service for the heater because it is more advanced and sophisticated than your traditional ones.

Rheem RTGH-84DVLN – Best Whole House Tankless Water Heater

The RTGH-84DVLN is an expensive beast. It is larger and heavier than the 64DVLN, being 9.8 x 18.5 x 27.5 inches large and weighing roughly 78 pounds. This heater features similar technology as the 64DVLN:

• The UMC-117 controller
• The included wire (for the controller)
• And all other technicalities

But, the 84DVLN is a bit more advanced (technologically speaking). It has a high-end display system that tells you temperature levels and details regarding functions and maintenance. This heater is also an excellent solution for high-altitude homes because it works correctly at 9,840 ft above sea level without any additional chips.

It is efficient when it comes to water and gas consumption, and its electric controls allow safer and more convenient use. It also has a built-in Self-Diagnosis system which tells you whether or not the heater runs appropriately, thus ensuring safe use.

Main Difference Between 64DVLN and 84DVLN

Well, the size. The 84DVLN is a better solution for more substantial, whole house use. For instance, with 84DVLN you can run multiple devices at the same time, such as the dishwasher and a washing machine while taking a shower at the same time. The 84DVLN also has a built-in fan that cools it and prevents overheating and prolongs durability.

And The Downsides?

If it helps, think of this devices as the 64DVLN’s big brother; it is larger, heavier and more expensive, but it is a better fit for larger homes and meets the whole household needs.

Noritz NRC661-DV-NG – Best High-Tech Tankless Water Heater

The NRC661-DV-NG is a mid-priced tankless water heater, fit for 2-bathroom homes. The NRC661-DV-NG is one of the Noritz’s new EZ Series heaters. Why EZ? In this case, EZ stands for “Easy” and refers to easy installation. Indeed, this tankless heater is extremely easy to install and is designed for faster and easier retrofits.

What does that mean? Well, most modern heater feature fits on the bottom, the NRC661-DV-NG has them on the top, ensuring that you can replace your old heater with this one without the need of changing your plumbing system. Also, Noritz recognized that most heaters don’t meet the needs of the North America market, which is why they decided to develop their EZ Series.

Using the NRC661-DV-NG ensures that you on-demand access to clean and hot water. Also, you can expect lower electricity and gas consumption should you decide to use it. It is environment-friendly, runs quietly and smooth and delivers an endless stream of hot water. It is also well built and “feels” sturdy. We also commend the digital temp control system and convenient Wi-Fi control. Plus, the instructions are well written, and you shouldn’t experience any problems during the installation.

Takagi T-KJr2-IN-NG – Best Indoor Natural Gas Tankless Water Heater

The T-KJr2-IN-NG is a mid-priced and energy efficient indoor tankless water heater. It is intended for indoor use and runs on natural gas, and is very compact (6.7 x 13.8 x 20.3 inches big). It is also easy to install, much more comfortable than Rheem and Rinnai models and weighs only 38 lbs.

While T-KJr2-IN-NG doesn’t meet the needs of larger homes and businesses, it is a perfect fit for small houses and apartments. Its energy-saving technology halves the gas bill, and the 6.6 GPM (standing for Gallons Per Minute) ensures consistent and convenient on-demand use. It features an energy factor of 0.81 to 0.83, which is more than enough to meet the needs of all you Greeners!

The T-KJr2-IN-NG is arguably the best solution for those that live in smaller homes. Also, you can install it in an apartment. For instance, if you make a living off renting apartments, installing this machine will not only cut down the bills but will also please your guests. It will also meet the needs of families with >5 members.

Rinnai V65IN – Best Compact Natural Gas Tankless Water Heater

With its energy factor of 0.82 (Energy Star) and a lightweight, compact design, Rinnai V65IN stands as an excellent solution to your hot water problems. This mid-priced heater uses natural gas or propane and features a built-in Temperature lock system to prevent accidental adjustments to the temperature.

This machine meets California and Texas emission standards and is energy efficient. The product weighs 45 pounds and is simple to install. It also has a built it, 2-Watt anti-freezing system that prevents any damage from low-temperature conditions. Due to its compact design, we suggest it for 1 or 2-bathroom homes.

For example, you can run two showers/baths simultaneously, but if you add in the use of another device (let’s say a washing machine), the Rinnai V65IN won’t be able to keep up with it. Again, this has nothing to do with the way this unit works; those are just the limitations of such design.

When it comes to maintenance, make sure that you flush it once a year, preferably with white vinegar (make sure that you use distilled vinegar.) And while you’re at it, it would be good that you clean the screen filter. Your gas consumption should be lower once you start using this heater, but not by a lot.

The V65IN also features a transparent screen through which you can monitor the levels and the color of burning gas. We recommend that you use it to control the quality of the gas and burning (the flame should be blue and burn steadily and evenly).

Takagi T-KJr2-OS-NG – Best Outdoor Natural Gas Tankless Water Heater

T-KJr2-OS-NG is another value for money and an energy-efficient heater made by Takagi, only this one is intended for outdoor use. It features an anti-freeze technology that allows it to endure low temperatures. This Takagi heater is a bit larger than the Takagi T-KJr2-IN-NG, but the weight is the same.

The water connection is located at the bottom of the heater (it is a 3/4-inch connector.) It is also worth mentioning that the heat exchanger is made of copper; the copper is not only an efficient conductor, but it can also function appropriately in an outdoor environment. It has a remote control system and does feature a non-condensing technology.

The T-KJr2-OS-NG doesn’t feature an Energy Star certification, and it isn’t as efficient as some other energy-saving heaters on our list. But despite the lack of this certificate, it still features a 0.82 energy factor. While there are some other outdoor tankless water heaters on and off our list, the T-KJr2-OS-NG is arguably the best.

Some people complained about the poor packaging, but the product did arrive safe and unharmed. T-KJr2-OS-NG is robust and durable and will require little to no maintenance, and that is what you need if you are looking for an outdoor water heater. We recommend this heater for small residences and apartments. The included control panel is also easy to use; just make sure that you protect it adequately.

Takagi T-KJr2-IN-LP – Best Gas Tankless Water Heater For Apartments

We already reviewed two Takagi heaters, both of which used natural gas (one was for indoor and the other for outdoor use.) Unlike them, the T-KJr2-IN-LP uses propane gas. When it comes to other features it operates similarly to the other two heaters:

• It has a flow rate of 6.6 GPM
• It weighs 38 pounds
• It has an Energy Star certificate, and so forth

Takagi T-KJr2-IN-LP also meets low NOx requirements, installs without any hassle and is pretty cost-effective. And, like other two Takagi heaters, it requires a 4-inch venting. Speaking of venting, the T-KJr2-IN-LP has a direct venting design, and its water-connecting inlets are located at the bottom of the heater.

This machine isn’t as efficient as we would like it to be, for it features a thermal efficiency of only 80%. The heat exchanger is made of copper, but we can’t confirm that this is pure copper (judging by the thermal efficiency rating, it isn’t.) It is powerful, and the 6.6 GPM flow rate will meet the needs of 2, maybe even 3-bathroom homes. You also receive a remote control with which you can quickly adjust the temperature.

The flow rate is steady, ensuring that every drop of water is appropriately heated. The constant flow of water provides not only comfortable showering but ensures that the water isn’t too hot or too low when you open the sink or use other appliances that require hot water. The T-KJr2-IN-LP also monitors the use of gas, ensuring that it delivers high flame when you are running the bath and low when you are using low water flow.

It would be cool if it allowed PVC vents, but this (and all other Takagi) you stainless steel wents only, which cost a lot more than the PVC ones.

Rheem RTG-64XLN – The Best Outdoor Natural Gas Tankless Water Heater

The RTG-64XLN is 14 x 10 x 26 inches in dimension and weighs 38 pounds. It runs on natural gas and delivers 6.4 GPM flow rate. It is relatively inexpensive and arrives with a UMC-117 controller. You will also receive a 10-ft wire for the thermostat.

This low NOx heater is intended for residential use, ideally for 1 or 2-bathroom homes. The included thermostat allows you to control both the temperature and power usage so that you can control the device more accurately and save energy. The best thing about the Rheem RTG-64XLN is its ability to keep the desired temperature level.

The flow is excellent too, always consistent and smooth. Also, it is arguably one of the fastest heaters on our list, ensuring that you spend little to no water while waiting for the desired hotness. Its efficiency is rated at 84%, which isn’t the best one on the list, but not the worst either. It won’t save you tons of money on gas and electricity, but you will notice a drop, especially if you are switching from tank-type to the tankless heater.

It is a bit difficult to install; a lot of people took instructions for granted and didn’t install it correctly. Consequently, their gas analyzers would always detect gas leaking. Please, call a professional if you can’t install it on your own. Other than somewhat difficult installations, we have no complaints regarding this item.

Rheem RTG-64DVLN – Best Value For Money Tankless Water Heater

The RTG-64DVLN is a low NOx and cost-effective water heater, an excellent solution to your water heating problems. It is quite compact, being only 14 x 10 x 26 inches in dimensions and weighing roughly 54 lbs. However, it isn’t as compact as some other low-priced devices on our list (like the EXCEL 1.6 and Costway,) but it is small in comparison to some other bigger beasts.

The RTG-64DVLN features a metallic finish and indoor direct-vent design. It is reasonably straightforward to install, and the Rheem customer service will gladly assist you during the installation process. In essence, all you need is access to an electrical outlet, and you are ready to install.

On the technical side, the RTG-64DVLN features an advanced concentric ventilation system. This system has a built-in condensate collector, allowing you to take long and hot showers with maximum safety and convenience. The product is durable and performs smoothly, ensuring that you always have hot water.

It is difficult not to recommend this heater, due to its compact design, high functionality and positive response from users. The only problem with this device (though, this can be said for all tankless gas heaters) is that you’ll have to wait a bit for a heater to warm the water, which might cause some inconvenience when you are looking for a quick hand wash.

The RTG-64DVLN is also an excellent replacement for your older tankless gas heater. It is conservating regarding the gas consumption and will reduce your gas bill (due to the low NOx system). And when the inspection arrives, feel free to let them know where you bought it, for they’ll surely be envious of you!

Excel – Best Indoor Tankless Water Heater For Boats And RVs

Excel is another low-priced and compact natural gas water heater. Its 1.6 GPM is sufficient for 1-bathroom homes and apartments. Interestingly, this heater features a Vent-Free technology for more convenient and more uncomplicated maintenance.

This heater weighs 20 pounds and is only 18 x 7 x 14 inches in dimensions, and you should have no problems figuring out where you can install it. Its compact design and white finish blend nicely with modern decor and space-saving needs. It has an ODS device that monitors oxygen levels and shuts down the machine if it detects any irregularities.

While it is intended for indoor use, you can use it outdoors too, but make sure that it doesn’t freeze during winters, and that you install it in a covered space. The casing isn’t the most durable in the world, but it will do the trick. The flow rate isn’t the greatest, but it will meet the needs of smaller homes, flats, and apartments. Theoretically, 2-bathroom homes could use it, but we didn’t test it for that so we can’t guarantee it. The manufacturer claims it is suitable for 2 or 2.5-bathroom homes.

But what we do commend it the low price, compact design, simple installation and a low-pressure startup that requires only 2PSI pressure to turn on. And if it starts leaking, the alarm will start beeping and worn you of these issues.

Camplux Heater – The Best Budget Outdoor Tankless Water Heater

Camplux heater is one of the most inexpensive units on our list. It is very light (29.8 lbs) and compact, a perfect solution for camping sites, apartments, even horse stables. Essentially, if you need a budget solution to your hot water problem, this is the item to fix it.

Though it is intended for outdoor use, you could install it indoors, but make sure that space has an adequate ventilation system. Also, should you use it indoors, you need to have a flue pipe that must be purchased additionally. It features quite an advanced combustion system that, together with other safety built-in systems, provides extra security.

The Camplux heater uses 2 D batteries, which you’ll also have to purchase additionally. It has a 20-minute cycle system and then shuts down to conserve battery and gas consumption. Camplux also has a very user-friendly customer service that will gladly help you with any problem or question.

Convenience is the name of the game for the Camplux tankless gas heater. It installs quickly and is simple to use. The 4.22GPM might not be an ideal solution for larger homes and facilities, but smaller residences will enjoy it. Even its 88.5% thermal efficiency rating is substantial, considering its price.

This product comes with two gifts:

1. One is the shower head with a built-in flow-control system
2. And the other is the gas analyzer to control the gas levels and ensure maximum safety

Camp Chef Triton – Best Portable Water Heater For Home Use

Last but not least s the Camp Chef portable water heater, intended for outdoor use only. It is inexpensive and has a 2.6 GPM flow rate, which should meet your hygienic needs while you are camping, hunting or fishing. It uses 2 D batteries for startup, which you’ll have to purchase additionally.

The product also arrives with a showerhead, which you can adjust to four options. It even comes with a carrying handle that folds and unfolds for space-saving needs. And, you’ll receive a gas regulating hose that controls the flow of gas (runs on propane gas). Its heat and flow adjusting systems are entirely accurate, allowing you to adjust them depending on your needs.

The garden hose is brass-made and compatible with standard hoses. Once the water starts flowing the heater automatically begins heating. Installation is simple, thanks to the included brackets for more straightforward mounting. We should also mention that this is one of the lightest heaters, weighing only 26.8 pounds.

We get it; you shouldn’t be fixing design errors! But, it’s a shame not to use this device due to this small design mistake. Those of you who live in wind-free areas can buy it freely, for it performs in all other parts quite efficiently.

Costway – Best Portable Propane Gas Outdoor Tankless Water Heater

This Costway portable heater is by far the least expensive item on our list. Because this is a portable heater, we believe that it is perfect for those that want to enjoy hot showers while camping or road-tripping. In short, it isn’t only meant for outdoor use, but also for those that enjoy outdoor activities.

This heater requires a 12V outlet, just like the one you have in your car. To use, just attach the heater to your vehicle’s power system and start using it! It delivers a consistent flow of water of up to 167℉. Most importantly, if it goes above 167℉, the Cosway portable heater will turn off automatically to prevent any damage.

Upon purchase, you receive a shower with a compatible water hose, a pump and a carrying bag for keeping everything in one place. Also, the bag helps you carry all these stuff safely and conveniently. Its water flow rate only 0.8 GMP, which is why you can’t expect a home-like shower experience. But, it will allow you to take showers, wash dishes or clothes in the wilderness; no other heater on our list can do that for you.

We were genuinely amazed by this product and recommend it to all outdoor-activities lovers. The heater itself is quality made, but the included cords and hoses could have been of higher quality. We believe that people would gladly pay more if the packaged included high-quality parts.

Best Gas Tankless Water Heater Buyer’s Guide

How To Pick The Right Model For You

When shopping for the best tankless gas water heater, there are a variety of factors that you need to consider carefully before deciding on the best option for you and your family. In our buyer’s guide, we’re going to be reviewing some of those factors in greater detail to help you make the best purchasing decision possible.

Understanding Capacity

The first and most important factor you should take into account when searching for tankless water heaters is their total heating capacity.

Unlike traditional water heaters, tankless models do not store water in a metal drum. Instead, they heat water at a constant rate as it is being used throughout the home.

To accurately calculate the correct water heater size that you need, you need to know the flow rate of the various appliances in your house. This includes faucets, dishwashers, washing machines, as well as bathtub and shower fixtures. You can likely find this information in the manuals that came with the faucets, fixtures, and appliances. Go ahead and write down all of the flow-rates that you find.

Using the numbers you just wrote down, go ahead and add up all of the water sources that you regularly use at the same time. A good combination to consider using is the total flow-rate of your dishwasher, shower fixture, and dishwasher. This number is the total GPM that your hot water heater likely needs to be able to handle to provide an uninterrupted supply of hot water.

The next step involves calculating the average temperature rise necessary to achieve your target hot water temperature.

Portability and Size

Portability and size is another area that you should focus on when searching for the best gas tankless water heater for your needs. With several of the options on our list, they are intended for smaller scale use for things like backpacking, camping, and washing down livestock. We took the time to specify which units fall into this category to avoid any potential confusion.

With those models, they do not support the required GPM rating for typical residential and commercial scale use. However, they are extremely easy to set up and usually don’t require any special electrical wiring. In addition, they can be stored away easily in a typical garage when you’re done using them.

For the full-sized models, the size of the unit can have a major impact on the installation process. Many of the smaller units are designed to be extra compact and are ideal for smaller spaces that are commonly seen in condominiums and townhomes.

Natural Gas or Propane?

With tankless water heaters, they are mainly designed for use with natural gas. However, many of the models come with special adapters that can be used to convert them to propane as well. When shopping for tankless water heaters, it’s important to know what type of gas source you plan on using beforehand.

Make sure that you’re purchasing a tankless water heater that is compatible with the fuel source you plan on using. When in doubt, it’s always best to contact the manufacturer directly to make sure the given model is compatible with your preferred fuel source.

Many of the available tankless water heaters may sell the propane conversion kits separately as well.

Think About Wiring

With many of the available tankless water heaters on our list, they are powered via a simple battery that is very easy to occasionally replace. These models are usually much more compact and are simpler to install. However, many of the more advanced models can require significant amounts of specialized electrical wiring for proper installation.

This type of wiring may require an update to your breaker box that will have to be carried out by a licensed electrician.

Don’t Forget Ventilation

When purchasing an indoor gas tankless water heater, you will almost always have to have a dedicated ventilation pipe installed. For the majority of full-sized models, this means that you will have to invest in steel ventilation piping. Unfortunately, this can prove to be a bit more difficult to install and is often much more expensive.

If you want to avoid venting altogether, your best bet may be a tankless water heater that is designed for exterior mounting. These types of products are much easier to install since they require no specialized venting. However, they are much more susceptible to outdoor conditions like freezing temperatures and more. In addition, having your water pipe located outside your home can increase the temperature rise level needed for the heater to work correctly.

Conclusion

With just a bit of prior planning and research on your part, you can easily find the best gas tankless water heater for your home. By following the information outlined in our buyer’s guide, you should be well on your way to finding the perfect water heater to fulfill your family’s needs.