Best Natural Gas Tankless Water Heaters To Buy in 2017

Product NameRinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater, Concentric/Twin Pipe InstallationTakagi T-KJr2-IN-NG Indoor Tankless Water Heater, Natural GasRheem RTG-64XLN 6.4 GPM Low NOx Outdoor Tankless Natural Gas Water heaterTakagi T-K4-IN-NG Indoor Tankless Water Heater, Natural GasTakagi T-KJr2-OS-NG Outdoor Tankless Water Heater, Natural GasRinnai RL94eN Natural Gas Tankless Water Heater, 9.4 Gallons Per Minute - OutdoorRinnai RUR98iN 9.8 Max GPM Ultra Series Condensing Indoor Natural Gas Tankless Water Heater with RecirculationTakagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute
Item Dimensions26 x 10 x 18.5 inches20.3 x 6.7 x 13.8 inches26 x 14 x 10 inches20.5 x 8.5 x 13.8 inches20.3 x 6.7 x 13.8 inches23 x 9.3 x 14 inches26 x 12.5 x 10 inches24.88 x 11.25 x 17.75 inches

We are assuming that it’s the search for the best natural gas tankless water heater that has led you here. Well, we are here to help. We’ve analyzed most of the tankless water heaters available on the market today. As a result, we reveal the top 8 best products in this category. We didn’t stop there. We also came up with detailed reviews of the best tankless water heaters. Read on!

Takagi T-KJr2-IN-NG Indoor Tankless Water Heater

The Takagi T-KJr2-IN-NG Water Heater is a product that enjoys an overwhelming support by homeowners across the globe. Don’t let its compact nature lead you into doubting its performance. This unit’s professional construction allows it to supply blazing hot water to up two application points in the warm climatic regions.

Its compact design allows it to occupy small spaces and install in few easy steps. Therefore, this unit will fit in the small homes in the best way. Its performance and usability allow us to confidently rank this unit among the best natural gas tankless water heaters.

What’s fascinating about the Takagi T-KJr2-IN-NG is that it performs better than the conventional tanked 40-gallon water heaters. It also boasts a high technological score.

The featured thermistors in this unit guarantee reliable water temperatures. Also, this unit comes with a fuel-air ratio sensor that ensures hardly any emissions get into the environment. The system is set to go off automatically whenever the machine overheats. Even more, this unit comes with extra safety features including surge protection, freeze shielding, and ability to troubleshoot and display diagnostic codes.

It utilizes natural gas with an input power ranging from 19500 to 140000 BTUs per hour. The flow rate of the supplied water is also practical. If you need a 35F temperature rise in the supplied water, then you can enjoy up to 6.6 gallons per minute. Again, if you need a 70F temperature rise, the hot water comes to you at 3.3 gallons per minute.

We appreciate the fact that this unit supports floor heating applications as well as hydronic baseboard.

Vertical or Horizontal Venting is mandatory for the successful installation of this unit as it works with gas. It demands a low activation rate of about 0.5GPM and a 110V electricity source. We advise the installation of this unit to be done by professional technicians. This will ensure total honoring of the provided warranty plan.

It weighs only 38 pounds and measures 6.7*13.8*20.3 inches. It doesn’t demand a large space. Therefore, you can transport and install it with utmost ease.

Say no more to struggling with leaking tanked water heating with the Takagi T-KJr2-IN-NG Indoor Tankless Water Heater. You are sure to love its low maintenance cost, top-notch performance, and ultra-durability. For those who mind the environment, we are happy to let you know that this unit is environmentally friendly.


  • Can be installed in a small area. This used occupies less space making it ideal for small homes.
  • High performance.
  • This device boasts a wide variety on its safety measures package that includes automated turn off when there is overheating.
  • The device is not heavy making installation and transporting less tasking.


  • Warranty is affected if the appliance is not installed by a professional.

Rheem RTG-64XLN 6.4 GPM Low NOx Outdoor Tankless Natural Gas Water heater

The best natural gas heater should provide a smooth transition from the traditional water heating systems. Well, with the availability of the Rheem RTG-64XLN model, you are almost there. You can now say goodbye to the inefficient conventional water heating methods. This is a unit that lives up to its promises of being as flexible, versatile, effective, efficient and as easy to use as possible.

This product comes with a whole load of amazing features. It brings you the exclusive next-generation water burner technology. This is what makes it a respected product among the available natural gas tankless water heaters.

For excellent performance as per your need, this unit brings you a wide range of power input options. It can work on power ranging from 11000 to 150000 BTUs. Thus, you are free to set a specific power input level depending on the water temperature and flow rate that you seek.

Also, this natural gas tankless water heater heats water to temperatures ranging from 100 to 140 degrees F. its hot water flow rates are also impressive. If you need a 35-degree F water temperature rise, the supplied hot water will come to you at 6.4 GPM. Again, if you need a 45-degree F rise, the hot water will come to you at 5.6 GPM.

Utilizing this unit is pretty straightforward and comfortable. The featured digital console displays the maintenance codes and the temperature settings. Also, a UMC-117 remote control is supplied with Rheem RTG-64XLN for easy temperature adjustment to exact degrees F.

What’s interesting, this unit suits use anywhere thanks to its high and low altitude capabilities. It will work in low to high altitudes up to 9840 ft. Above the sea level without a chip. Even more, through the available EZ-link cable, you can now connect two or more of this unit to serve as one in areas with high demand for hot water.

For those who mind the environment, we are happy to let you know that this unit is environmentally friendly. In fact, it meets the SCAWMD Rule 1146 requirements.

We recommend professional installation of this unit for disappointment free experience. However, if you prefer installing the Rheem RTG-64XLN yourself, it shouldn’t trouble you. A comprehensive, easy to follow guide is available for every buyer. Also, various installation components like the temperature wire come with the package. You will also need the following items for the successful installation of this unit. Ground lines, circuit breakers, pressure, relief valve, and weatherproofing materials.

While this is not an all-perfect natural gas tankless water heater, it still has solid features to suit installation at your home. Its power allows it to serve various application points concurrently while providing reliable hot water flow rates. Also, its eco-friendly certification allows it to stand out from the large pool of natural gas tankless water heaters out there. Also, it’s clear that the Rheem Company minds your satisfaction. They provide you with extras including a temperature wire and the remote controller. With all these amazing traits, nothing should stop you from going for this unit.


  • It can work on a good range of power input.
  • A notable hot water flow rate.
  • Relaxed use of the device as it comes along with a remote control making it easy to adjust the temperatures.
  • Can work well irrespective of the area's altitude.
  • It has the environmental friendly feature.


  • Installation by a professional is highly recommended.

Takagi T-H3-DV-N Condensing High-Efficiency Natural Gas Indoor Tankless Water Heater

Deciding on the best natural gas tankless water heater to buy is not a walk in the park. But when you get the best one, you will enjoy a lot of benefits.

We start off by informing you that this unit has all you need to enjoy an endless supply of hot water anywhere. It’s a product that we recommend to any homeowner. Two things stand out, power efficiency and an enticing warranty plan. These are some of the factors that allow this unit to rank among the best.

So, what makes the Takagi T-H3-DV-N a fantastic natural gas tankless water heater? Let’s start by going through its features and performance.

This unit utilizes natural gas. Thus heat exchangers and internal burners get active when they sense cold water in the pipes. Also, worth mentioning, is that this tankless water heater features a condensing system. It works by condensing the steam running in the combustion chamber. This is before turning it into the outlet hot water that comes to you through the drain. These, among other features, make the Takagi T-H3-DV-N exclusive.

What about power? This unit demands 199000 BTUs per hour to perform in the best way. So, ensure that your ground lines are living up to its requirements.

Now, with enough power supply, this heater provides 10 GPM. This is huge! With such a high flow rate, this unit beats all average heaters out there that only offer 2-4GPM. Upon installation, you will have no reason not to use hot water for any application.

This supplies hot water to various application points at reasonable flow rates. Please note that if you dwell in the very cold climates, you will have to bear with lower flow rates.

The released hot water’s temperatures can be as high as 185F. So, if you need to replace a water heating system that provides good amount of heated water, this is your match.

A high-performance tankless water heater is nothing with inferior usability traits. With that in mind, the Takagi manufacturing builds the T-H3-DV-N with utmost care. It weighs only 60 pounds. Though not as lightweight, this unit’s weight is lower than that of most of its competitors.

We recommend professional installation of this natural gas tankless water heater. Its tricky drainage system can only demand to tackle by the professional technicians. But, if you feel that you can carry out the installation yourself, do it. You will need various items including a drain, hose, ground wires and a valve kit.

What’s interesting, you can integrate the Takagi T-H3-DV-N with a remote controller. The remote will help you set an exact temperature for your hot water.

We recommend this unit. Its price might be high, but its performance is impressive. It will provide you with enough value for your hard-earned money. With it running at your home, you will be free to enjoy hot water application at various points.


  • This product has an attractive warranty from the manufacturer.
  • Automatic turn on when cold water gets into the appliance.
  • A high-temperature output of up to 180F.
  • You can integrate it with a remote controller. This allows the user set the exact desired water temperature.


  • Installation requires a professional.
  • Lower hot water flow rates when installed in cold regions.

Takagi T-K4-IN-NG Indoor Tankless Water Heater

Takagi is a trusted brand. Their many years of experience allow them to come up with exclusive water heaters. The Takagi T-K4-IN-NG Indoor is a product that lives up to their promises. It comes to serve your home in the best way by providing a convenient source of hot water.

It’s a compact, energy efficient, wall-mounted water heater engineered for whole-house services. What’s interesting, the Takagi T-K4-IN-NG brings you a flexible venting. This allows for both indoor and outdoor installation. Again, you are free to install this unit in either vertical or horizontal position.

It suits space heating and potable water heating in commercial or residential properties. It’s power efficiency, and ultra-durability makes it a one-of-a-kind product.

This unit features an advanced design and construction. This is together with of advanced water heating technology. These tow allows it to offer convenience, reliability, and safety to its users. Included in its making are sensors, microprocessor, and thermistors. These components are there to control the heating operations. Control the parameters and activate ignition. Even more, they help in modulating the water and gas flow for an accurate factory. And temperature setting and power efficiency.

With full modulation, this heater can run with power ranging from 11000 to 190000 BTUs per hour. We love the fact that this unit provides an energy factor of up to 0.83. Also, with its modulating gas valve, you can do more. You are free to set this unit to serve very high demands for hot water or the mild applications.

Upon installing the remote control, you can vary the outlet water’s temperature from 99F to 167F. But without the remote control, you can only use the 4 temperature settings, ranging from 113F to 140F.

Especially pertinent, you won’t have to deal with impractical hot water flow rates. This is because this unit is set to provide up to 8 GPM. Thus, you can now enjoy using hot water in up to 3 application points at high flow rates of up to 2GPM. This is is not matter your climatic region.

Also, we appreciate the fact that this unit comes with a self-diagnostic system. Whenever any components malfunctions, the LED light will blink on the computer dashboard. Again, if you have the remote installed, an error code will come to its screen. Every consumer knows the valuable benefits of a self-diagnostic system.

The Takagi Company also minds your safety and satisfaction. They have incorporated various safety features in the Takagi T-K4-IN-NG. The internal freeze protection system in this unit is there to shield it from freezing. This is when the external temperatures go below 36.5 F.

A HI limit function deactivates it when the temperature rises beyond the max level. Again, the overheat cutoff in this product is there to shield the heat exchangers. This is in case of excessive heat emission. Other safety features in this unit include the water flow sensor and the fuel/air ration rod.


  • You can install it both outdoor and indoors. Either in a horizontal and vertical position.
  • Advanced heating technology addressing the need to have safety in water heating
  • It has a temperature variation system that allows regulation. The temperature range can be from 140F to up to 167F after the installation of a remote control system.
  • Hot water with a high flow rate for three application points.
  • The hot water output is not affected by the climate.
  • A self-diagnosing system that alerts the user in case the unit goes faulty.
  • An inner freeze protection system that prevents the water heater from freezing. This is vital during very low temperatures, especially during winter.
  • Has a full pack of safety features to ensure it works well without harm.


  • Installing the remote control system which, proves to be an upgrade comes in at an extra cost.

Takagi T-KJr2-OS-NG Outdoor Tankless Water Heater

The Takagi T-KJr2-OS-NG stands out for its compact design and minimal NOx compliance. It also boasts an energy star rating. It comes to allow home dwellers to enjoy an endless supply of hot water at practical flow rates.

It’s a non-condensing tankless water heater. It utilizes natural gas to get the job done. But, with correct integration with a conversion kit, this unit can use propane gas.

We love its compact nature. This unit measures 20.5″ H * 13.8″ W * 6.7″ D and weighs only 33lb. So, installing it in your limited space is possible. Keep in mind that this unit is for outdoor installation. Even more, this unit supports wall mounting. So, you can free up your ground space to serve other purposes. With all these installation capabilities, you’ll have hot water always!

Even more, this unit provides practical hot water flow rates. If you need a 30F temperature rise, you will enjoy flow rates of 6.6 gallons per minute.

For homes in areas where the water bears temperatures of about 70F, do not worry. Also if you have up to two baths that need to run together, this is your match. Even in areas with water temperatures of about 55F you will enjoy running a hot single bath.

This unit demands a gas power input of 140,000 BTUs per hour. Its make allows it to perform better than any 40-gallon tanked water heater. Also, we appreciate its support for radiant floor heating tools, and hydronic baseboard. You can also use this unit to supply domestic hot water to plumbing appliances and features.

What’s more, this unit will save on your power bills to a great extent. It boasts an energy star rating of up to 0.83.

Your safety and the durability of this unit are its manufacturer’s top priorities. Because of this, there are various safety features in this heater. They include an overheat cutoff fuse. Water and exhaust temperature control function and an internal freeze-shield protection system.

With this tank, you will protect the environment from degradation. This is because it features an air/fuel ratio sensor. This is what that has earned it a low NOx emission compliance certification.

We recommend this unit for use in small houses, apartments, and cottages. During installation use the services of a professional. This is not for safety only, but also warranty. We are confident that this unit will serve you with no disappointment whatsoever. Go for it!


  • This unit efficiently uses energy.
  • Uses natural gas but can also use propane gas.
  • This natural gas water tank can fit both in indoor and outdoor installation.
  • Small in size thus it occupies less of your precious home space.
  • Safety features. It has a cut off to avoid water overheating.
  • This appliance is environmentally friendly and does not produce harmful emissions.


  • The hot water supply when the climate temperatures are low.
  • It's best for small households.

Rinnai RL94eN Natural Gas Tankless Water Heater

Rinnai has yet another professional-quality model to its name; the RL94eN. In simple terms, this is another good reason to trust in this brand. It’s sleek, ultra-effective and efficient. It’s engineered to provide nothing but accurate value for your money. It boasts a compact design with an appealing silver color. It also has a precise design for outdoor installation.

With the capability to offer 9.45 GPM of hot water, the RL94eN suits large homes with many dwellers. Also, if you need to run various hot water use points at the same time, this is your match.

It has a favorable flow rate and the ability to raise the water temperature by 30F. Thus, anyone living in the freezing areas will love this unit.

What caught our attention is that this unit enjoys federal tax credit exemption. This is thanks to its energy efficiency. Thus, with its application, you will be free to enjoy tax rebates. Again, you can now save a good amount on electricity or gas energy. This unit will reduce your energy bills by up to 40%.

If you’ve been using the lower GPM heaters, this unit brings a significant difference. It will get a consistent supply of hot water at non-fluctuating temperatures.

Also, we like its digital screen and touchpad that makes temperature setting a breeze. You don’t have to struggle to achieve your preferred water temperatures. A few touches on the screen and you good.

The company understands that you need to reap tangible fruits from your investment. That’s why they provide impressive warranties to back every component of this unit. It offers a 12-year warranty on the heat exchangers.

These are the most valuable elements of your natural gas tankless water heater. Again, the parts are not left behind as a 5-year warranty covers them. Even more, the Rinnai Company provides a 1-year warranty on labor costs. The amazing warranty offer is an invitation to buy this unit with utmost confidence. The warranties also form concrete reasons to trust the Rinnai Brand.

The calibration process for this unit might be tough for some consumers. If power outages occur in your area, you might have to restart this unit. If you fret about mechanics, the process might be a nightmare for you. Luckily, the manufacturer provides a comprehensive user guide with this unit. By following it, you will manage to carry out the calibration process yourself. Ensure that the system is empty before restarting.

A vast pool of natural gas tankless water heaters is out there. But the Rinnai RL94eN model stands out in various aspects, as seen above. If your home needs a high supply of hot water GPM, this might be the best option for you. It also carries considerable energy saving, durability, and backup traits. Consider it for installation at your home or commercial property.


  • This water heater has a sleek compact design and comes in an eye-catching silver color.
  • It's ideal for outdoor usage
  • Suits a place with a large number of occupants.
  • Serves a high demand for hot water.
  • Tax rebates come along as this device
  • Meaningful saving on energy
  • Has digital display alongside a touchpad for temperature setting. This makes using this appliance super cool.
  • It has a remarkable warranty the manufacturer


  • In case of a power failure, this unit needs a restart, which can be quite tasking for some users.

Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater

Rinnai RUC98iN is another reliable and innovative natural gas tankless water heater. This unit will not only save you time but your money too. It’s a product that ranks among the best products in this category with no hassle. We appreciate that Rinnai offers you twin-pipe PVC and concentric venting options. Also, this unit is easy to install, with or without expert intervention. Let’s dig deeper to see what it has to offer.

The Rinnai RUC98iN has a professional design with a focus on the needs of the average homes. Its power requirements range from 15200 to 199000 BTUs. Thus, it has all you need to maintain a consistent supply of hot water to your home. But might not be ideal for huge houses or areas with very high demands for hot water. But, it’s able to support a showerhead and the kitchen with ease.

This unit has the power to provide hot water with temperatures between 98F and 140F. This makes it ultra-flexible. To your amazement, these degrees can go as high as 185F. All you need is to buy a commercial remote. This makes it possible to use the unit in an average commercial property.

With the Rinnai RUC98iN, energy saving while enjoying an endless supply of hot water is no longer a dream. It’s able to save up to 96% of energy. Its efficiency doesn’t vary even when you using propane gas. This will result in a great reduction in your monthly bills. You only need a 2 watts power supply to keep this unit up and running. But, during winter, this unit demands 140 watts power to shield itself from frost.

As mentioned earlier, this unit comes in two venting options: PVC and Concentric. This trait allows it to stand out on the market. You are free to choose from the two available options for installation.

We understand that you are also yearning for a high hot water flow rate. Well, this unit won’t disappoint. The hot water flow rate in the Rinnai RUC98iN ranges from 0.26 to 9.8 GPM. Needless to say, this unit is among a few others with high water flow rates.

Especially relevant, this unit features a compact and lightweight design. Thus, it will suit installation anywhere around your home’s setting. It measures 26*18.5*10 inches, a smaller size than that of most suitcases. Also, it weighs only 80 pounds.

Controlling this unit is as easy as pie thanks to the featured remote control. The controller will let you adjust the hot water temperature with ease.

Finally, you get to enjoy fantastic warranty on this unit. The manufacturer provides a 5-year warranty on the parts. You also get a 12-year warranty on its heat exchangers. Even better, the manufacturer covers labor throughout the first year of use.

With all these features, the Rinnai RUC98iN tankless heater is definitely worth buying. We are confident that it’s an ideal option for an average home or commercial property.


  • Easy installation even without expert skills
  • Flexible temperature set variation.
  • Long warranty good giving the buyer a secure feeling.
  • Continued hot water supply enough for the kitchen and a showerhead.
  • High energy saving ability.
  • Allows installation in two options, the PVC and concentric. It best suits your home depending on the form of venting available.
  • High hot water flow rates.
  • Has a superior design
  • Its light weight is an advantage.


  • It is not suitable for a place with a very high demand for hot water
  • It uses more energy during winter.

Rinnai RUR98iN 9.8 Max GPM Indoor Tankless Water Heater

Could you be looking for a high-grade natural gas tankless water heater? Then considering this model by the Rinnai Company is a wise decision. This unit leads in Rinnai’s Series of tankless water heaters. It’s sought due to its endless supply of clean and blazing water. It’s ideal for home or at any of your properties.

The Rinnai RUR98iN model came into the market in 2014. Particularly pertinent, it suits indoor installation. It uses condensing technology to offer steady supplies of hot water to homeowners.

This heater also features a pump and thermal bypass valve. These 2 make the use of the water heating re-circulation technology possible. These components allow for faster hot water production, reducing your waiting time. As a result, you can now say goodbye to time wastage in the quest for hot water. Also, this recirculation technology minimizes greenhouse emissions as well as energy consumption.

Even more, the Rinnai RUR98iN comes with a 24-hour digitized controller. Thus, controlling it is a breeze and ultra-effortless. This function offers you hot water usage for 24 hours throughout the year. As a result, you’ll cut your energy consumption by a significant degree.

This unit also has a remote control for error code and temperature display. With this function, you can control the output water’s temperatures with no hassle from 98F to 140F. Also, you can tell when the system is malfunctioning thanks to the prompt error code display.

Its other impressive features include isolation valves and dual heat exchangers. These 2 features offer several years of service with little servicing. They also go for long with no need for replacement.

The best thing with this tankless water heater is that it can use propane gas too. This is possible through the use of a conversion kit.

The Rinnai RUR981 has impressive performance too. This natural gas water heater produces 199,000 BTUs of power. Again, it supplies 9.8 GPM of hot water flow rate. This strength is able to support up to 4 baths at the same time.

Another sweet spot with this unit is that you can reduce the power output to as low as 15200 BTU. The flow rate can also go down to 0.26 GPM. As such, whether you need this heater for a small home or business, it’ll still perform. Reducing the power output and water flow rate helps in cutting down the electricity bill.

Worth noting, RUR981 is a direct vent natural gas heater. It comes fitted with dual pipe CPVC/PVC or concentric vent configuration.

We recommend this product. It’s a tankless water heater with incredible features worth investing in. It also boasts professional construction and top-notch performance.


  • Suitable for indoor installation
  • Steady hot water supply
  • Has a little negative impact on the environment. Its re-circulation system lowers harmful greenhouse emissions.
  • Equipped with a digital controller, using it is ABC easy.
  • Provides for a 24-hour hot water management.
  • Features a remote controller that displays the temperature and error code. This alerts you of any malfunction.
  • Can function with both natural and propane gas.
  • High hot water flow rates that can serve even four tabs.
  • It has an adjustable power output aiding the user on saving on energy.


  • The flow rate goes hand in hand with the power input.