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10 Best Gas Tankless Water Heaters 2021

If you’re energy-conscious and in demand of getting a tankless water heater that will save your energy and power, natural gas tankless water heaters have vastly grown in popularity over the past few years. Natural gas is in higher demand compared to previous years, and on many occasions, more so than the Propane-powered tankless water heaters.

In this article, we made a compelling guide on how to shop for the best gas tankless water heaters and a compelling list of our best picks.


Things to look for in the best gas tankless water heaters

  • Gallons per minute – No one wants to run out of hot water, especially when it’s cold; that’s why it’s important to look for a suitable gas tankless water heater with an appropriate gallons per minute ratio that will ensure constant hot water flow.
  • Proper venting system – The gas tankless water heater needs to be equipped with a proper venting system, which can be very challenging. Proper venting is responsible for various safety features as well as channeling gas out from the household to prevent unnecessary water heating.
  • Warranty – It’s important that your gas water heater can be equipped with a proper warranty with the company assisting you whenever a malfunction happens. Be wary. However, some companies provide extended warranty only if you purchase a certified professional to install your system.
  • Anti-freeze cold safety – Most of good gas tankless water heaters provide reliable services and computerized features for safety designed specifically for colder areas where temperatures reach frigid levels. That said, a good tankless water heater should have these protections.
  • Energy-factor – Energy factor is important because it’s supposed to provide more energy efficiency according to research, which can lead to low annual operation costs. Make sure to always look to Energy Star level or at least 90%+ energy efficiency to meet the demands. Also, there are various certifications that make using the product more comfortable.

Research for the best gas tankless water heater

In addition to the aforementioned features and settings to look for, the right research for the best gas tankless water heater is also important, especially because you’re purchasing it online and not from the store.

The first thing to consider is how difficult or easy they are to assemble, mount and install. Despite being mainly compact in size, these tankless water heaters can come or require additional vents and pipes to make them more practical when it comes to water distribution across the bathroom. That said, the size of your apartment also plays a large role in the installation.


Usually, most brands offer the lifetime warranty if you allow their technicians to install the water heater, as mentioned above. Often, it’s a good practice because that way you have a professional determines the most practical position for your heater without worrying about damaging certain electrical circuits or other appliances in the apartment or something else.

If you have plumbing or handyman knowledge on your own, you’re good to go about the installation, although it’s still necessary to look into some YouTube videos and documentation, as well as the manual to be sure about what you’re doing.

It’s important to consider the price of the unit installation. Using a gas tankless water heater may cost you over $3,000 to install, as opposed to the electric units that cost around $1,500. That said, they have a much higher initial cost, but are worth investing in on the long run compared to the electric tankless gas heaters that require you to pay more. Also, the annual cost for the natural gas is around $163, while electric heaters will whoop the numbers on your electricity bill every month.

Finally, it’s important to research the brand itself. A good brand will provide tankless water heater of a lifespan from 15 to 20 years, and even extending into the 30 years with Rinnai’s tankless water heaters. Stay away from shady manufacturers, look for reliable warranty and customer support, and more importantly, the user-based reviews on shopping sites, forums, YouTube and others.

The Best Gas Tankless Water Heater We Recommend?


Now after we determined what are the best properties to look into when buying a new mattress, it’s time we announce which one is the clear winner. We sorted them into the best overall, best budget and best compact model.

  1. Best gas tankless water heater overall – Rinnai RUC98iN
  2. Best gas tankless water heater for the budget – Eccotemp i12-NG
  3. Best compact gas tankless water heater – Gasland BE158 1.58GPM

1. Rinnai RUC98iN (the best gas tankless water heater overall)


  • Price: $$$
  • Weight: 82 pounds
  • Dimensions: 10 x 18.5 x 26 inches
  • Warranty: 12/5 years

Rinnai RUC98iN is an ideal gas tankless water heater if you have a large household and someone’s constantly using the bathroom and is in demand of simultaneous warm water. It uses natural gas to distribute and heat the water for the household, being more energy-efficient than electricity. It’s also equipped with advanced technologies, which make it even more environmentally friendly compared to the electric tankless water heaters. It heats the water extremely fast and can distribute it in the entire household extremely fast. Starting at $1,540 plus the materials needed to assemble it and professional installation, RUC98iN is extremely expensive and maybe too much for the mid-range family’s wallet, as well as smaller households that are not in need of large water distribution.

It can output 9.8 gallons per minute, which allows simultaneous baths and showers, as well as the use of sinks or faucets. Additionally, it can also be used for washing laundry several times before the water gets cold. Its innovative controls allowed it to heat extremely fast between the temperature of 98 degrees F to 140 degrees F. In addition to that, it’s extremely compact and can easily fit into space. Given that tanked heaters were popular until recently, it will make you rejoice that it takes less space than a tank.

Despite being energy efficient and earning the Energy Star certification which benefits consumers’ bills, it’s still worth noting that its professional installation can take from between $3000 up to $4000, whereas the solo installation can take up to $1,500, which is too much for a smaller family to handle. Additionally, depending on the location, it arrives with different PVC or concentric vents, meaning that you may have to spend additional money on certain OEM parts.

It’s great for both residential and commercial use, although while residential warranty comes with 12 years of limited support, commercial warranty is downed to 5 years.


  • Energy-efficient, relatively compact, ultra-fast, large temperature range.


  • Extremely expensive, may require additional OEM parts.

2. Eccotemp i12-NG(The best for the money)

Eccotemp i12-NG – The best budget gas tankless water heater

  • Price: $
  • Weight: 28.9 pounds
  • Dimensions: 16 x 16 x 11 inches
  • Warranty: 2 years

If you’re looking for a reliable and powerful natural gas tankless water heater, Eccotemp i12-NG is going to deliver both stylish design and outstanding performance. Because of its modern and stylish appearance, it’s going to appeal to almost any position in the house, including smaller homes and apartments. It uses black tempered glass on its front panel, and it’s equipped with LED display controls, which make setting the temperatures easier and more intuitive. Whether you want to position it in the bathroom, lobby, or kitchen, it doesn’t matter; the minimalistic yet modern design will fit it pretty much anywhere.

The heater at the whole is rated at 3 GPM and uses on-demand performance without the pilot light requirement. This feature makes it more environmentally-friendly because it can be used to reduce energy consumption. The automatic temperature controls provide energy-saving mode too. Additionally, there’s also a child-lock technology, which makes it easier to control with children who are curious and like to tinker around everywhere. Also, the product plays it safely through a safe electronic ignition system, which prevents unexpected hazards.


  • LED display controls are more intuitive for users, electronic ignition system, 3 GPM flow rate, energy-efficient, stylish design.


  • It can get extremely hot under strong performance; installation is difficult and may require professional help.

3. Gasland BE158 1.58GPM(The best compact gas tankless water heater)

Gasland BE158 1.58GPM – The best compact gas tankless water heater

  • Price: $
  • Warranty: 1 year
  • Weight:
    5 pounds
  • Dimensions: 8 x 6.1 x 17.3 inches
  • Warranty:

Gasland’s heaters are usually extremely portable and lightweight, intended for smaller homes and offices, and the BE158 is no exception. Despite being able to fit into small spaces and be extremely portable, it’s still packed with a plethora of bells and whistles both smaller and larger homes can benefit from. The lightweight and compact design allowed it to be placed anywhere, from lobbies and hallways to kitchens and bathrooms. That said, it’s incredibly easy to mount and replace if needed. It is equipped with smart mounting bracket which allows easy and fast installation within minutes.

Additionally, Gasland added a lot of safety and protection features to flatter this product. First, it is equipped with a flame failure device, as well as anti-freeze protection. That said, you can easily conclude the product is intended for both hotter and colder climate. In addition to two advanced protection systems, there is also overheating protection which prevents malfunction by stopping heating once the water pressure extends 110 psi. The heater will begin cooling automatically and prevent it from further overheating.

The device features the maximum power output at 41,000 BTU/hour with water easily getting heated up. Additionally, you won’t have to preheat to use it as it’ll automatically start heating fast. There’s also around 1.58 GPM that can then be properly adjusted.


  • Portable design, a lot of BTU, nice water flow, plenty of protection systems, easy to assemble


  • Slightly difficult user manual.

4. Takagi T-H3-DV-N


  • Price: $$
  • Weight: 59 pounds
  • Dimensions:2 x 17.8 x 24.9 inches
  • Warranty: 15 years if it’s used for domestic purposes.

Takagi is another natural gas tankless water heater that has an emphasis on more compact and space-saving devices. It’s model, T-H3-DV-N is no exception and has been available on the market for a good while, building great reputation among consumers. It has a compact design, which makes it easily placeable anywhere in the apartment or in the house, although it is mid-sized, so still be wary of where you place it.

It has various computerized features, which makes temperature adjusting a breeze, with plenty of options available to adjust the heating, waterflow, and other things. It provides on-demand usage, which makes it more environmentally friendly.

In addition to all of its features, it sports all the necessary protective settings that allow improved safety, without the pilot light to worry about. The company also said that the water heater satisfies the 2012 SCAQMD Rule about ultra-low NOx emissions.

The only drawback, however, is that it can be challenging and tedious to install, although once the process is done, it’s one of the best gas tankless water heaters on the market.


  • Modern design, various computerized features, safety enhanced, environmentally-friendly


  • Hard to install.

5. Rheem RTGH-95DVLN


  • Price: $$
  • Weight: 79 pounds
  • Dimensions:5 x 9.8 x 27.5 inches
    Warranty: 5 years, 1 year on parts.

Rheem is a popular tankless heater manufacturer and one of the established names when it comes to providing sturdy, durable, and reliable tankless water heaters. Its model we reviewed, RTGH-95DVLN is no exception. It provides the 94% energy efficiency thanks to its stainless-steel condensing heat exchanger, which lets no heat go into waste, providing constant water on-demand.

Furthermore, the gas tankless water heater boasts smart electronic controls which, not only contribute to better energy efficiency but are better for user-end management, as well as preventing hazardous situations thanks to its protection protocols against the hot weather, freezing and overheating.

It supports a two-pipe direct vent system for the PVC pipe, which means it can be used for simultaneous multiple showers. Another drawback of it is that it’s pretty difficult to install and could even take days without proper equipment and the help of professionals. Additionally, it runs pretty loud, so you should consider placing it somewhere, where its noise won’t affect your other everyday activities.


  • Energy-efficient, not too large, great for extremely hot temperatures, a lot of safety-oriented features


  • Loud, challenging to assemble and install, expensive

6. Rheem RTGH-84XLN


  • Price: $$$
  • Weight:
    54 pounds
  • Dimensions: 14 x 10 x 26 inches
  • Warranty: 12 years

If you live in a super-large household and have a large family that is in constant use of water, Rheem RGH-84XLN is worth checking out, with a lot of useful and favorable features at times of need. This gas tankless water heater is great for those who want to save both energy and water. Thanks to its intuitive computer options, you can decrease the water flow in the pipes and make it customized to your needs.

Also, there’s a lot of low fixture capability. The water heater is fixed at the maximum water flow rate of 8 GPM, although it still excels at reliable providing of hot water to all household members, bathrooms and sinks. The heater begins delivering hot water at 0.40 GPM. That means that when the water demand is low, the heater will reduce the GPM to prevent the temperature from fluctuations.

Its LCD screen has many more functionalities than providing information about water temperature and safety features and settings. It additionally helps with maintenance by displaying warnings and information about its current health. So, not only it’s easy to install, it’s also easy to maintain. There’s another feature called electrical blower that re-channels the gases from the heater to the outside surroundings to prevent your house or apartment from overheating.

The reason why this gas tankless water heater is suitable for larger homes is because of its size. It’s not the most compact heater, so make sure to check its dimensions and weight before you purchase it.


  • Energy and water-efficient, low-flow fixture compatibility, smart LCD screen with a lot of features, built-in electrical blower.


  • It’s not so compact.

7. Eccotemp FVI-12-NG


  • Price: $$
  • Weight: 29 pounds
  • Dimensions:
    4 x 15 x 24 inches
  • Warranty: Lifetime warranty if installed professionally

Not everyone can benefit from owning a gas tankless water heater the same, especially those who live in smaller apartments on their own with only one bathroom. Finding both compacts, and adjustable water heaters that don’t have high hot water demands is difficult. However, Eccotemp FVI-12-NG will change your minds. Eccotemp FVI-12-NG is one of the most cost-effective options for small families and apartments, yet it’s not cut short of various features that make it demanded a lot.

One of the best features of FVI-12 is that it offers a lifetime warranty for its users, although there is a catch. You’ll have to hire a professional to assemble the heater if you want the lifetime warranty to take effect. Even if you don’t, bear in mind that this natural gas tankless water heater can be installed easily, even without professional guide and within a few hours.

It performs as expected for a budget water heater. However, it’s worth noting that it’s not entirely powered by natural gas. It also boasts an LED display for the temperature, which instead of the gas, is powered through electricity. Nevertheless, even though it’s not so energy-efficient at 79%, the temperature display won’t take too much from the energy.

It heats up quickly, saves a lot of space, and is equipped with power venting. There is also a built-in exhaust fan that will push out the gases from your home to prevent unnecessary heating. It also looks stylish and doesn’t take too much space, so it can be placed wherever you want.


  • Easy to install, power venting, stainless steel vent comes with it, great for small places


  • Low energy efficiency at 79%

8. Rinnai RUR98iN


  • Price: $$$
  • Weight:6 pounds
  • Dimensions: 5 x 10 x 26 inches
  • Warranty: 12 years

If you’re not tight on budget and you’re looking for a natural gas tankless water heater that is going to last, you may find a lot of Rinnai RUR98iN’s features quite useful, and you most likely won’t have to search for a new gas tankless water heater for decades.

One of the best characteristics that describe the RUR98iN is its great vents and safety systems that make it safer compared to its competition. It is equipped with the right, universal pipes to establish a stable channel of water across your apartment or a house. It’s worth noting that because of its size and capabilities, this tankless heater is the best in larger households where it can host several simultaneous showers and service more bathrooms than one.

You can choose between two venting options – concentric or PVC; although that is mainly determined depending on the hot water requirements you’ll need. The device is equipped with a 9.8 GPM flow rate, which is great for providing quick output of hot water for multiple bathrooms.

Another great thing is its energy efficiency, which is listed at 96%, meaning that it won’t pollute environment and will also save additional energy and bills for you.


  • Huge flowrate, endless water supplies, energy-efficient, two venting options.


  • Too expensive.

9. Noritz NRC661-DV-NG


  • Price: $$
  • Weight: 39 pounds
  • Dimensions:
    7 x 13.8 x 23.6 inches
  • Warranty: 12 years

Noritz is a mid-range natural gas tankless water heater, and its compact design and ease of installation made it stand out in our eyes. It is powered by natural gas and is ideal for two-bathroom homes and apartments. Although it will function much better in the southern parts of the USA, it is pretty reliable in the north where temperatures are more frigid.

It provides an endless amount of hot water on demand, with the maximum water output of 6.6 gallons per minute. Thanks to its large capacity, you can have at least two simultaneous showers, or washing machine plus shower at the same time. Its energy-efficient features enabled it the Energy Star certification, which extremely important to those who are conscious about the planet and want to save the gas.

Although you can’t install it without some basic plumbing skills, NRC661 is still extremely easy to install compared to some other natural gas heaters we’ve mentioned earlier. Also, the unit doesn’t require a high-temperature vent, which is often difficult to track down. Instead, it uses the Schedule 40 PVC pipe and fittings, which are more accessible and easy to install.


  • Great design, great for mid-range homes, large water flow, supports simultaneous showers


  • Slightly expensive for a mid-range device.

10. Rinnai RL Series HE+


  • Price: $$$
  • Weight: 3 pounds
  • Dimensions:
    14 x 10 x 23 inches
    Warranty:12 years

This is the last of the Rinnai natural gas tankless water heaters, as well as the last in our list, although nonetheless important. Just like the other Rinnai products, it’s not recommended for smaller homes because of its chunkier than compact infrastructure, although it has great capabilities for larger households with more than two bathrooms.

It is highly efficient and provides 9.4 GPM water flow, which makes it ideal for both hotter and colder environments. Its high flowrate also makes it suitable for simultaneous showers, sink, as well as running a washing machine at the same time as a shower. It boasts high power efficiency and is equipped with proper vents that enable users to set hot water to be available on demand. Another great thing about Rinnai’s tankless water heater is that it comes with a 12-year warranty, although it may appear way too difficult for installation if you don’t have the handyman experience.


  • Large water flow, energy-efficient, suitable for simultaneous showers


  • Chunky, hard for installation


This section concludes our lengthy list of the best gas tankless water heaters. If you don’t want to use natural gas, you should see the best Propane-powered tankless water heaters. Additionally, if you’re looking for power-efficient electrical tankless water heaters, check out this list. We ensured to craft this guide with a lot of features and necessary information which will help you have an easier time understanding technical info that often needs to be broken down into easier points to be understood.

Hopefully, this list provides enough resources for both larger homes and smaller households with less than two bathrooms. Additionally, if you want simultaneous running of more appliances that require hot water, make sure to check the more high-end options from our list such as Rinnai’s