8 Tankless Gas Water Heaters – (Reviews of Natural and Propane Gas Tankless Heaters)

Let’s start with the facts. You are probably researching on this website because you are one of the millions of Americans who have an aging water heater and you know that it’s usually the second biggest energy hog in your home. And truly, doesn’t everyone want to save as much money as possible on their water and energy bills? Let’s assume you have made it this far to realize you want to buy the best tankless water heater, but you are not quite sure if you should choose an electric unit or the natural gas or propane-powered tankless heaters. You can trust that we have put together a great list of the best tankless gas water heater review to help you make this decision.

Here is the lowdown: gas units are more powerful, which means that they are best for if you have a busy family who uses a heavy amount of hot water (showers, dishwashers, clothes washers and hot water taps combined). Or if you have a home with upgraded, luxury bathroom fixtures, or even a vacation home, tankless gas water heaters are your best choice. Another option is to use a gas tankless unit for commercial applications like small restaurants or beauty salons, etc.

It must also follow that gas tankless water heaters are more expensive. Gas tankless water heaters are also engineered to have great efficiency — especially if you go with one of the condensing units. Condensing models are more expensive because they are designed to pull the exhaust heat (combustion of burning gases) back into the heater to reheat water, and then forcing the cooler air through the exhaust. This not only makes the unit more efficient for you, but also makes the exhaust process safer and allows you to use cheaper materials in that piping.

So, all that being said, you will not be disappointed if you choose a gas unit. It will provide the comfort and consistency of endless hot water. Here are eight options of gas tankless water heaters that we have reviewed for you.

  • RUC98iN
  • Brand: Rinnai
  • Dimensions: 10 x 18.5 x 26 inches
  • GPM: 9.8
  • Weight: 82 pounds
  • Warranty: Limited 12-year
  • T-KJr2-IN-NG
  • Brand: Takagi
  • Dimensions: 6.7 x 13.8 x 20.3 inches
  • GPM: 6.6
  • Weight: 37 pounds
  • Warranty: 10 year
  • RL94eP
  • Brand: Rinnai
  • Dimensions: 9.3 x 14 x 23 inches
  • GPM: 9.4
  • Weight: 46 pounds
  • Warranty: 12-Year
  • NRC661-DV-NG
  • Brand: Noritz
  • Dimensions: 6.7 x 13.8 x 23.6 inches
  • GPM: 6.6
  • Weight: 38 pounds
  • Warranty: Manufacturers

Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater

While this unit is at the higher end of the price range, its features make users rave about its options. Rinnai is pretty proud of the fact that they are the only water tank manufacturer to offer two installation options in one unit—saving you the hassle of buying extra parts. This Rinnai tankless water heater offers two options for natural gas venting—both concentric and PVC pipe options are found on the top of the unit for convenient access during installation.

This concentric vent design is very unique with its important safety benefits. The concentric vent means that it holds both intake and outtake pipes, so the vent is cool to the touch as the warm air is insulated inside. If a intake or outtake pipe develops a leak, the air stays in the concentric vent and does not enter the home. The dangers of a gas leak are immeasurable; from fire and combustion to carbon monoxide poisoning.

The Rinnai RUC98iN is quiet, compact, and gives you immediate hot water when you want it. Because the water is being heated on demand, there can be a slight drop in water pressure if multiple showers are running at the same time. Also, be sure give a tankless unit about 8-10 seconds to clear the cold water out of the pipes before jumping into the shower expecting hot water.

The Rinnai RUC98iN is certified through Energy Star with a rating of 0.96. This tankless water heater will not only work to save you money on your energy bill, but will also save space—it is about the size of a small suitcase at 10 x 18.5 x 26 inches.

Check the Latest Price on Amazon

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

As a smaller natural gas tankless water heater option (6.7 x 13.8 x 20.3 inches), Takagi recommends this unit for apartment residents or smaller family homes with 1-2 bathrooms. That smaller size also brings a lower price tag, for those looking for tankless water heaters at economical prices for their home.

For installation, Takagi requires 4-inch category III stainless steel venting for the T-KJr2-IN-NG. Some other units give piping and material options for venting, but this unit requires the stainless steel. Some installers have suggested mounting your unit as near as possible to your vent, and configuring your water and gas lines a little bit farther to the Takagi, in order to save money on the more expensive stainless steel venting.

It is also Energy Star certified with a energy factor range of 0.81-0.83. If you are looking to save money on your natural gas bill and use hot water on demand, this is a great unit to try for your home. The Takagi T-K Jr. 2 offers a flow rate maximum of 6.6 GPM (gallons per minute), which is typically enough to run a dishwasher, a shower, and a washing machine all at the same time. If it happens that more hot water is demanded, the water pressure would drop slightly in the faucets or showerhead.

Check the Latest Price on Amazon

Rinnai RL94eP Outdoor Propane Tankless Water Heater

The Rinnai RL94eP comes in with a higher price tag, but for propane users who need an outdoor unit, this sleek water heater confidently fits the bill. In a comparison of the best tankless water heaters, you will definitely want to keep the Rinnai luxury line in mind. Outdoor water heaters remove the need for costly and time-consuming venting needs for indoor units. If you live in a climate that can support an outdoor unit, the RL94eP is a great option to consider.

If you want one of the highest GPMs of hot water for your home or commercial application, the Rinnai RL94eP offers an impressive 9.4 gallons per minute. That translates into at least five different simultaneous demands for hot water; such as two showers, a dishwasher, washing machine and a sink all at the same time.

The Rinnai RL94eP is Energy Star certified with an energy factor of 0.82. It also features a patented recirculation program that cycles water through at peak demand times (like the early morning hours) to provide the most efficient and best water temperatures for your family. For those with young children in the home, you can depend on the certainty of the Rinnai’s temperature lock to prevent scalding or burns from the tap or the showerhead.

Check the Latest Price on Amazon

Noritz NRC661-DV-NG Indoor Condensing Direct Tankless Hot Water Heater

The NRC661 is Noritz’s newest efficient condensing model. If you have the space indoors to mount this unit nearby your existing gas lines, making the switch to a tankless water heater won’t be too much trouble. The NRC661 is in the mid-high end of the price range, but that is to be expected with a condensing gas-powered unit. Best for warmer climates with two bathrooms, or northern climates with 1.5 bathrooms, you should be able to power a shower and two taps with hot water simultaneously. Alternately, it would not be too hard to stagger your hot water use to make sure you have enough water pressure for the demand in need. If you go with the NRC661, you will know that the condensing technology will help save energy. As an Energy-Star rated appliance, it has an Energy Factor (EF) of 0.91 for the natural gas hookup. That rating is significantly higher than a comparable water heater tank. The maximum BTU input per hour is 120,000 BTU, and it is recommended to use a half-inch gas line for installation; up to 120 feet in length.

Check the Latest Price on Amazon

  • T-H3-DV-N
  • Brand: Takagi
  • Dimensions: 11.2 x 17.8 x 24.9 inches
  • GPM: 10
  • Weight: 59 pounds
  • Warranty: Manufacturers
  • RTG-95XLN
  • Brand: Rheem
  • Dimensions: 14 x 10 x 26 inches
  • GPM: 9.5
  • Weight: 54 pounds
  • Warranty: Manufacturers
  • RTG-64XLN
  • Brand: Rheem
  • Dimensions: 14 x 10 x 26 inches
  • GPM: 6.4
  • Weight: 54 pounds
  • Warranty: Manufacturers

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

When you buy the Takagi T-H3-DV-N, you will be spending in the high end of the price range. Here is what you are paying for in that price: a highly efficient condensing unit that allows you to use PVC piping for venting, and still gives you 13-22% in gas and electric savings pricing over the non-condensing unit.

The Takagi T-H3-DV-N offers an awesome 10 GPM capacity, which should be enough to power four showers in a warmer climate or three showers in a colder climate. This unit is best for homes that use a heavy amount of hot water, or have radiant heat. It is even rated for small commercial operations, so its factory temperature is set at 180 degrees F instead of most other units at 120 degrees F.

The Takagi T-H3-DV-N also meets the 2012 SCAQMD rule 1146.2 for ultra-low NOx emissions, so it is Energy-Star qualified. You get a lot of bang for your buck with this unit.

Check the Latest Price on Amazon

Rheem RTG-95XLN 9.5 GPM Low NOx Outdoor Tankless Natural Gas Water Heater

If you are looking for a good tankless water heater, let’s say for a home with a busy family, this Rheem RTG-95XLN would be spot-on. It will be at the top of the price range, due to its 9.5 GPM, and its low NOx emissions.

The beauty of the outdoor gas-powered RTG-95XLN is that you do not have to worry about the venting like indoor units. Highly efficient with an energy factor of 0.82, you will appreciate the ease of installation and service with its 3″/5″ concentric vent system with an integrated condensate collector.

For install, the RTG-95XLN is compatible with ½ inch gas lines. Rheem’s RTG units comes standard with hot-start technology that programs the heater to help minimize fluctuation in water temperature when it is in high demand. The company also claims to have the “industry first” with their minimum flow rate of 0.26 GPM, which is really helpful for low-flow fixtures that are trying to save water. And its minimum activation flow rate is 0.40 GPM, which means all house members will receive hot water; even in low-demand instances.

Check the Latest Price on Amazon

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

Rheem has done a fine job with the 6.4 GPM output for homes that have a lower-to-average level of hot water needs. The Rheem RTG-64XLN is at the middle of the price range due to its flow rate of 6.4 GPM and its natural gas energy source.

Engineered to be installed outdoors for mild or temperate climates, this natural gas tankless water heater also comes with a temperature remote control. Thankfully you will not have to walk out to the unit to adjust the temperature manually. This line of Rheem heaters has low-NOx emissions, and it has a 0.82 energy factor for efficiency. Count on the Rheem RTG-64XLN for standard ½” gas line compatibility for easy hookup on the outdoor installation.

RTG units like the Rheem RTG-64XLN features a water savings setting that reduces the water flow in the pipes until the heater can reach your ideal temperature, and will then ramp up and increase to your desired flow rate. RTG-64XLN offers an impressive minimum flow rate of 0.26 GPM, which is standard in the RTG line and the first in the tankless water heater industry. Rheem has also engineered a minimum activation flow rate of 0.40 GPM, offering instant hot water even in those low-demand hot water situations.

Check the Latest Price on Amazon

Rheem RTG-84XLN 8.4 GPM Low NOx Outdoor Tankless Natural Gas Water Heater

The Rheem RTG-84XLN will fit in the mid-high end of the price range due to its 8.4 GPM water flow and its natural gas energy source. Engineered to be installed outdoors for mild or temperate climates, this unit does also come standard with a remote temperature controller.

Rheem offers a super line of mid-range tankless heaters, this one with 8.4 GPM flow output for users who demand high volumes of hot water. It should be known that Rheem declares the 8.4 GPM for a 35 degree temperature rise from water inlet to output. If you need to raise your inlet water temperature more like 70 degrees, the GPM would reduce by half to 4.2. Warmer climates can then expect the higher GPM over some colder northern regions.

Also, if you want to save more energy, there is a water savings setting that reduces the water flow in the pipes until the heater can reach your ideal temperature, and will then ramp up and increase to your desired flow rate. This unit is also part of Rheem’s low-NOx emission line, and offers a 0.82 energy factor with its all-copper heat exchanger.


In a comparison of tankless water heaters, it can be said that tankless gas water heaters take the cake. While they do have a higher price tag (not including installation pricing and labor), their capacity and high efficiency ratings lay out the features that explain those costs. It is also worth noting that with regular care and maintenance, a good tankless water heater should have a much longer lifespan than tank-style heaters. That should then help to average out the price.

What about indoor units versus outdoor installation? If you live in a warm, moderate climate you will be able to use an outdoor unit. Not only will that help save you money on the venting costs, you won’t have to worry about your pipes being subject to harsh weather and freezing. For northern, cold climates, you will be best off if you use an indoor good gas tankless water heater. The obvious reason is to avoid your pipes from becoming frozen and bursting, but local ordinances might also require the unit to be installed indoors. Check with your local plumber or search online to find out your state’s regulations.

Another important and interesting point to mention is that the United States Department of Energy periodically changes the Energy Factor (EF) requirements of home appliances to help consumers conserve energy and ultimately save money. The most recent change came in 2015, and gas-powered tankless water heaters now must have an EF of 0.82. It must also be said that those changes apply to any new units being manufactured; if the unit was made before 2015, the old EF still applies. You might be shocked to research and find out how low some of the Energy Factors are on the old tank-style water heaters.

It can be said that the best tankless water heater will vary in different applications or climates. What is important is that you find a tankless water heater review that describes your specific home’s needs, your climate, and your price range. We earnestly hope that our time and effort in reviewing these tankless gas water heaters has been helpful and valuable for your search to find the perfect fit.