Finding the best tankless gas water heater can be a difficult undertaking due to the fact that there are such a large number of models on the market right now. What's more is that many of the models share strikingly similar features making it a hard task to pick a unit that really stands out.

There are many advantages to opting for a tankless gas water heater over their electric counterparts. For a start they are usually much more powerful with vastly higher demand capacities. This makes them perfect for large families and households with high hot water demand. They can also operate on a much bigger temperature interval and heavily outperform electric units in colder climates and do just as well in warmer environments.

You will initially pay slightly more than you would if you chose the best electric tankless water heater, however over time this difference will correct itself due to the difference in gas and electricity prices. Gas heaters usually have an energy efficiency rating somewhere in the region of 80-85% but can heat water to higher temperatures more easily.

An important thing to note before we get started with our gas hot water heater reviews is that a tankless gas water heater will require annual inspections and check ups as they have combustion mechanisms. These mechanisms must be installed professionally and regularly inspected to ensure there are no leakages or malfunctions.

Below you will find our best gas water heater reviews of the top 5 best tankless water heaters and tankless gas water heater prices on Amazon 2017. Make sure you pay attention to the different models’ specs and to their features and advantages over their rivals. Warranty options, service and maintenance costs are also factors to bear in mind.




83% EER

94% EER



best gas water heater reviews


The T-KJR2 is one of the best products of its kind on the market right now. It combines sleek, space saving design with a robust, reliable construction and sheer power. Takagi are pioneers in the field of Gas Tankless Water Heaters and the associated technology.

This is the smallest tankless gas water heater in the Takagi tankless line. Despite being slightly smaller than other models it is more than powerful enough to meet the high hot water demand needs of any American home, with an impressive maximum flow rate of 6.6 GPM. It can do anything that 40 gallon electric water heaters or tank models can do and the compact wall mounted unit can even support hydronic baseboard and radiant floor heating applications.

The T-KJR2 has a respectable energy efficiency rating of 84% and is an environmentally friendly product. Another reason why this is such a stand out model is its versatility in regards to installation. It can be converted into a direct-vent unit by using the optional TV10 conversion kit for installation in more confined spaces.

It can also be installed using larger connections than usually found on your typical gas tankless water heater. This allows more water through the input, thus increasing your overall hot water flow. Yet another exceptional feature is the integrated Frost Guard technology which will be of interest to those of you who live in colder climates. This will protect your investment and ensure you and your family have uninterrupted hot water, even during the most aggressive of winters.

Overall this is an outstanding product. More compact than your standard gas model yet still incredibly powerful. Respectable energy efficiency rating, multiple advanced features and a solid warranty scheme make the T-KJR2 maybe the best natural gas tankless water heater

Best For:

  • Medium to large families and residences 


  • Natural Gas
  • Min BTU: 19,500
  • Max BTU: 140,00
  • Voltage: 120
  • Copper heat exchanger
  • Weight: 38 pounds
  • Dims: 6.7 x 13.8 x 20.3
  • 84% energy efficiency rating
  • Non-condensing technology​
  • Direct vent capability
  • Electric ignition
  • 10 year warranty on heat exchanger
  • 5 year warranty on parts


  • Extremely powerful unit
  • High output capability
  • Reliable and very strong construction


Rheem are a highly respected company in the gas water heater field and this is another great release from them. A powerful and reliable unit which would be perfect for those of you in residences with medium-high level hot water demand.

This tankless gas water heater is an outdoor, wall mountable unit with an impressive flow rate of 6.4 GPM, meaning it should have no problem whatsoever meeting the needs of medium to large family homes. Possibly the best natural gas water heater and this is the low NOx emissions version for increased energy efficiency, making it a much more environmentally friendly product.

The RTG-64XLN boasts a whole host of impressive features. Such as next generation burner technology for improved water heating, a low activation flow rate of just 0.45 GPM, remote control thermostat ability, freeze control, a self-diagnostics program and many, many more.

This is a methane ventilation unit and due the advanced technology within and the low NOx emissions it has no need for cumbersome ventilation systems made of heavy grade materials such as stainless steel, a simple PVC setup will suffice with this model, making installation much faster and simpler.

All in all a very, very good unit indeed with a multitude of advanced features and innovative technology within, particularly impressive considering that this is a gas model. 

Best For:

  • Medium to large sized families and residences​


  • BTU Min: 11,000
  • BTU Max: 150,000
  • Flow Rate: 6.4GPM
  • Weight: 54 pounds
  • Dims: 14 x 10 x 26
  • Temperature Range: 100-140 degrees F
  • ​120 Volts
  • Copper heat exchanger
  • Outdoor, wall mounted installation
  • Energy efficiency rating of 82%
  • 12 year warranty for heat exchanger
  • 5 year warranty for parts and labour


  • Low NOx emissions
  • Exceptional warranty scheme
  • Reliable brand name of Rheem
  • Best natural gas tankless water heater

ecotemp fvi-12-ng

This tankless water heater gas unit is another that could fall into the category of best natural gas water heater. This forced vent, 3.4GPM indoor heater is designed for small to medium hot water demand and capable of supporting more than one application simultaneous. It is perfect for vacation cabins, cottages and smaller homes. It pulls only around 2 W when idle and 10 W during operation making it a very energy efficient unit indeed.

The FVI-12-NG sports water pressure activated electronic ignition technology, with a minimum PSI rating of 40. This also takes into consideration different factors such as the incoming flow temperature and the desired water temperature, again adding to the energy efficiency of the unit.. As mentioned above it is powered via natural gas only and comes complete with a horizontal stainless steel vent kit for easier installation.

This gas tankless water heater has a sleek appearance and a compact, space saving design making it perfect for homes where potential installation space is at a premium. This is highlighted further still by the products conservative dimensions and the fact it weighs just 20 pounds. Rest assured however that its small stature does not mean lack of ability. This is a powerful and reliable unit from a highly respected brand.

This really is a great choice for medium and smaller sized residences and is just as good, if not better than most 40 gallon electric water heaters. Compact yet robust design, highly reliable, an abundance of wonderful features and a very good flow rate for a unit that targets the low demand market. If energy efficiency is what you are after then this is the unit for you, also this is one of the lower tankless gas water heater prices you will find. If you need a natural gas unit then this could be the best natural gas water heater for you.

Best For:

  • Residences with medium level efficiency requirements​


  • ​Min BTU: 25,000
  • Max BTU: 74,500
  • Flow Rate: 4.8 GPM
  • Weight: 33 pounds
  • Dims: 15 x 6 x 25
  • 120 Volts
  • 79% energy efficiency rating
  • 2 year warranty


  • Space saving design
  • Easy installation
  • One of the cheaper models on the market


Rinnai are a company that improve upon their models year after year, continuously adding new technology and features in an effort to produce the best possible product. Some recent additions have been the integrated Circ-Logic recirculation technology which recirculates hot water for added efficiency and also an improved leak detection feature.

The RL94IN is one of the most powerful units on the market right now. It boasts an very impressive flow rate of 9.4GPM and can support continuous hot water at a pre-set temperature for up to 5 simultaneously running applications. Despite its high capacity and sheer power it is still more than capable of saving you up to 40% on your energy bills, an impressive figure indeed.

For such a solid and robust unit it is surprisingly compact. It sports a space saving design and as a result is easily interior mountable, unlike some of the other larger gas models on this list. Sometimes with larger gas models that are interior mounted there can be a real issue with ventilation, however that is not a problem with this model. It sports an intelligent concentric ventilation system meaning it can be vented directly to the exterior of you home or building through a variety of different options.

Overall this is an outstanding product. If you have a large family or are in a residence with a very high demand then the RL94IN might just be for you. Great features, compact yet solid construction, highly reliable and just an incredible flow rate and capacity. Highly recommended.

Best For:

  • Large residences​


  • ​Min BTU: 9,900
  • Max BTU: 199,000
  • Flow Rate: 9.8 GPM
  • Weight: 50 pounds
  • Dims: 14 x 9.3 x 23
  • Temperature Range: 98-140 degrees F
  • 83% thermal efficiency
  • 12 year warranty on heat exchanger
  • 5 year warranty on parts
  • 1 year warranty on labor for residential installations


  • High capacity water heater
  • Digitally controlled temperature regulation
  • Can operate on both gas and propane

rheem rtgh-95dvln

​The RTGH-95DVLN is a high end product indeed. Upon looking Inside this unit it is clear that Rheem have made a real effort to separate themselves from the competition in this area of the market. Both large and subtle differences really make it standout. This model is also ideal for those of you who have a premium of space available for installation yet still require a powerful tankless gas water heater.

Inside you will find a high quality stainless steel heat exchanger which is a huge improvement on your typical copper exchanger found in the majority of these types of water heaters. It also boats a highly impressive energy efficiency rating of 94%, very impressive indeed for such a large and powerful model. One of the main contributing factors to this has been the upgrade of the internal, intelligent electronic temperature controls that provide higher accuracy in temperature regulation and energy output. These also act to improve the overall safety of the unit.

As mentioned above the RTGH-95DVLN is loaded with innovative features. A major improvement on previous models has been the new enhanced scale detection feature which really helps prolong the life of your investment. Others include the impressive self-diagnostic program which in conjunction with the digital interface displays temperate readings and maintenance codes.

It is also a very good direct vent gas water heater, utilizing PVC piping for flexibility and to keeps costs down. Should you be someone who finds themselves with exceptionally high demand then this model comes with an EZ link cable which can connect 2 units together and have them act in unison which is a brilliant feature. Also freeze protection protects your purchase​ down to climatic temperatures as low as -30 degrees F.

We could go on and on about the features of this wonderful tankless water heater. Perfect for high demand residences who want to save on space, keep emissions down and improve their energy efficiency by a considerable amount. An absolutely outstanding product, a strong candidate for the best natural gas tankless water heater.

Best For:

  • High demand households​


  • Min BTU: 11,000
  • Max BTU: 199,900
  • Awarded industry best low activation flow rate standard
  • Weight: 79 pounds
  • Dims: 18.5 x 9.8 x 27.5
  • 94% energy efficiency rating
  • Integrated condesate neatrilizer
  • 120 Volts
  • Space saving construction
  • 5 year warranty on heat exchanger and parts
  • 1 year warranty on labor​


    • Freeze protection technology
    • Energy star efficiency meaning it has an energy efficiency rating of over 94%
    • Advanced ventilation system



A gas tankless water heater was the original version of the tankless water heater which is replacing the older style tank water heaters. As their name suggests they are operated by way of natural gas and/or propane.


As you have probably noticed above they tend to be bigger and have a much higher capacity than that of their counterparts. As a result they can sometimes be less energy efficient however may be a better option if you have a particularly large family and/or high demand household.

As they are gas operated another thing to take into consideration with these units is ventilation. This is not something that has to be accounted for with electric units so should you opt for a tankless water heater gas be sure you have sufficient room on the exterior of your home for installation and ventilation.


As mentioned above in our gas hot water heater reviews and in many other best gas water heater reviews the main considerations when selecting are high capacity output, energy efficiency and ventilation. If you have a large family then you may want to look into these models further given you have the requisite space for installation.

If you fall into this category then look into energy efficiency ratings. Have a look at your current energy bills and your existing units energy efficiency percentage. If savings can be made then look at your purchasing budget and tankless gas water heater prices. By piecing all of this data together and combining it with our best gas water heater reviews above you should have all the info you need.

top picks



This is a unit that is the ultimate in high capacity hot water delivery. An essential model for very large families and households with the highest of water requirements.

It also sports an abundance of advanced technological features and an impressive warranty scheme making it perfect to provide your family with limitless amounts of hot water on demand.​



Small gas water heater units with low demand ​do not really exist in any meaningful way. What is important to look for if not high capacity though is energy efficiency.

​This unit by Rheem is one of the most technologically advanced units on the market and has an Energy Star rating due to its exceptional efficiency rating, perfect for saving money on bills.


Picking the best tankless gas water heater for you might be a tough job, but when you follow simple guidelines and look for specific features it might become easier than you think.

We have narrowed down your choice to 5 of the world’s best at this moment in our gas hot water heater reviews. This is so you don’t have to spend countless of hours in front of your computer reading through the specs of hundreds of heaters, as we’ve done all the reading for you. Finally be sure to check out our comparison table for the 5 products we listed to summarize the above mentioned information easier.