best tankless gas water heater reviews of 2023



If you are planning to switch from an electric tankless water heater or traditional tank water heater to a cheap alternative, gas tankless water heater is a good option. Conventional water heaters have large storage tanks that need constant maintenance to keep the hot water running.

These tank water heaters incur huge costs in repair and maintenance. Considering a tankless heater does help reduce numerous factors such as waiting time for hot water, energy costs, and maintenance costs. However, it will be best to have a good energy star rating and large capacity tankless gas unit to heat water for use.

A gas unit is worth considering if you live in an area where there are cold temperatures. The efficiency rating of tankless gas heaters are an average of 85%. Meaning it is a good option to consider for reducing the cost of electricity which could otherwise be wasted to adjust for the temperature rise(difference between incoming and output temperature of water).

Because the electric tankless water heater will stop producing the GPM to heat water as it will be working to normalize the cold water first and then provides warm water. But, the tankless gas water heaters’ heating power (GPM) is also very significant compared to their electric tankless water heaters counterparts. And, Tankless gas water heaters are the ones that reduce the power costs as compared to electric units.

what is tankless water heater?

According to, It is a device that heats water as it passes through it and does not store water in itself other than the heat exchanger coil. Most heat exchangers preferred in tankless water heaters are made of copper and are prone to scale buildup. Nevertheless, they do provide high thermal conductivity.

the 10 best tankless gas water heaters of 2023

We’ve selected 10 different variants of Best Tankless Gas Water Heater so you can get an idea of the differences between the models. We’ll tell you what we liked and didn’t like about each model, and we’ve even included a short buying guide that outlines what you can expect from each model.


You may also like to read about the best electric tankless water heaters.


best overall:

By Brighnessguru industrial experts.

Rinnai V94iN

Rinnai V94iN Non-Condensing Natural Gas Tankless Water Heater

The Rinnai V94iN Non-Condensing Natural Gas Tankless Water Heater is a compact and powerful solution for your hot water needs. With a high flow rate of 9.8 GPM, this water heater can handle up to 6 fixtures at once, ensuring that you never run out of hot water. This energy efficient water heater includes enhanced scale detection to prevent damage and a 15-year warranty for the heat exchanger, labor and parts. This gas powered water heater is also perfect for indoor installation and it can be made even smarter with Rinnai Controlr for WiFi connectivity (not included).


Flow Rate: 9.8 GPM


Power Output: 199,000 BTU


Dimensions: 17.5 x 30 x 13 inches


  1. High flow rate
  2. Smart design


  1. Not energy star qualified
  2. Professional installation recommended.


runner up:

By Brighnessguru industrial experts.

Rheem RTGH-95DVLP-2

Rheem RTGH-95DVLP-2 Indoor Liquid Propane Tankless Gas Water Heater

The Rheem RTGH-95DVLP-2 Indoor Liquid Propane Tankless Gas Water Heater is a highly efficient and affordable option for your home. One of the features of this water heater is its exclusive Water Savings technology which conserves up to 1,100 gallons per year, making it an eco-friendly choice. With a flow rate of 9.5 gallons per minute and a power output of 199,900 BTU, this tankless water heater can easily handle the demand of continuous hot water.

Also, because its high energy efficiency is rated by a Uniform Energy Factor (UEF), this tankless water heater saves expensive power costs. This tankless gas water heater is Energy Star certified, meaning it meets strict energy efficiency guidelines set by the government. Additionally, its Hot Start Programming minimizes cold water bursts, keeping the output temperature steady.


Flow rate: 9.5 GPM


Power output: 199,900 BTU


Dimensions: 27.5 x 9.75 x 28.5 inches


  1. Energy efficient
  2. Affordable
  3. Energy Star certified


  1. Indoor use only


best budget:

By Brighnessguru industrial experts.

Rheem Mid-Efficiency 7.0GPM Indoor

Rheem RTG-70DVLN-1 mid-efficiency indoor tankless water heater

One of the gas tankless water heaters is Rheem RTG-70DVLN-1 mid-efficiency indoor tankless water heater that provides continuous hot water for homes with up to 3 bathrooms. With a flow rate of 7.0 GPM and a heating capacity of 160,000 BTU, this unit is energy efficient and cost-saving. In addition to this, like most tankless water heaters by Rheem, RTG-70DVLN-1 also features an exclusive Guardian Overheat Film Wrap for added safety and an EcoNet enabled mobile app for convenient control.


Flow rate: 7.0 GPM


Power output: 160,000 BTU


Dimensions: 9.88 x 13.88 x 25.63 inches


  1. Provide unlimited hot water
  2. Energy efficient
  3. Convenient controls


  1. Professional installation required


best low price:

By Brighnessguru industrial experts.


MAREY GA10FLP Liquid Propane Tankless Gas Water Heater

The MAREY GA10FLP Liquid Propane Tankless Gas Water Heater is an eco-friendly, battery-powered option for those looking for compact tankless units and energy-efficient solution for their hot water needs. With a flow rate of 2.64 GPM and a heating power of 68,240 BTUs, this tankless heater is perfect for indoor use in apartments, cabins, and small homes.

Moreover, this water heater activated by water flow rather than water pressure and features temperature control with a convenient summer/winter switch.

With a host of safety features such as auto cut-off, automatic ignition, anti-dry combustion, over gas pressure, overheating, flameout protection, and twin solenoid valves, this tankless gas water heater is a reliable choice for any household.


Flow Rate: 2.64 GPM


Power Output: 68,240 BTU


Dimensions: 6.89 x 13.58 x 23.62 inches


  1. Eco-friendly
  2. Compact
  3. Provides sufficient hot water


  1. Lower heating capacity.


best portable:

By Brighnessguru industrial experts.

GASLAND Outdoors

GASLAND Outdoor Tankless Gas Water Heater

The GASLAND Outdoors Tankless Gas Water Heater is a portable and convenient option for outdoor hot water needs. With a flow rate of 1.58 GPM and a heating capacity of 41,000 BTU/Hr, this hot water unit provides instant and endless hot water on demand. It is also one of those tankless heaters that is CSA approved for safety and features multiple safety protections such as flame failure device, anti-freezing protection, and over-temperature protection.

In addition to its portable and powerful design, this Tankless Gas Water Heater also comes with a QCC1 Type1 Propane Adapter with Gauge, making it easy to monitor the propane tank level and even use as a leak detector. This tankless heater is a perfect combination for outdoor activities like camping, beach trips, and even washing pets.


Flow Rate: 1.58 GPM


Power Output: 41,000 BTU


  1. CSA approved safety
  2. Lightweight and portable
  3. supply hot water on-demand


  1. Limited heating.


best for low usage:

By Brighnessguru industrial experts.

Eccotemp i12-NG

Eccotemp i12-NG Tankless Gas Heater

The Eccotemp i12-NG Tankless Gas Heater is a good option for homes with less demand of hot water. With a flow rate of 4 GPM and a sleek, modern design, this best tankless water heater activates only on demand and does not require a pilot light, consuming less energy.

Featuring fully automatic temperature controls, an energy saving mode, and child lock technology, this water heater also has a safe electronic ignition system and can be plugged into a standard 110v electrical outlet. Plus, the included horizontal venting allows for quick and easy installation.


Flow Rate: 4 GPM


Power Output: 80,000 BTU


Dimensions: 15.70 x 27.50 x 10.90 inches


  1. Powerful flow rate
  2. Energy-efficient
  3. Easy installation


  1. Not recommended for high elevations



By Brighnessguru industrial experts.

Noritz NRC71DVNG

Noritz NRC71DVNG Indoor Condensing Tankless Water Heater

The Noritz NRC71DVNG Indoor Condensing Tankless Water Heater is a powerful and efficient option for supplying hot water in fixtures. With a flow rate of 7.1 gallons per minute, this tankless heater delivers high flow rates and can be vented using 3″ Schedule 40/80 PVC, PP or CPVC. The advanced heat exchanger design and built-in controller make this tankless gas water heater a top choice for those looking for energy savings and hot water delivery.

Unlike traditional water heaters, this gas-powered tankless water heater has a compact and space-saving design, making it perfect for those with limited space. It also has a uniform energy factor of 0.89 which makes it worth considering. This gas water heater ensures low Nox feature that is environmentally friendly and safe for indoor use. The unit ships complete with a 6′ power cord and various adapters and terminations are available to allow for a wide array of venting options.


Flow Rate: 7.1 GPM


Power Output: 157,000 BTU


Dimensions: 6.7 x 13.8 x 23.6 inches


  1. Endless hot water
  2. High efficiency
  3. Compact design


  1. Requires additional kit which increases installation costs.


best non-condensing:

By Brighnessguru industrial experts.

Rinnai V65iN Non-Condensing

Rinnai V65iN Non-Condensing Natural Gas Tankless Water Heater

The Rinnai V65iN Non-Condensing Natural Gas Tankless Water Heater is an affordable option for those in need of a reliable hot water source. The Rinnai Tankless Water Heater has an Energy Star qualified uniform energy factor of 0.82 and offers a flow rate of up to 6.5 GPM, making this water heater an excellent choice for homes with multiple fixtures. The heating capacity is also adjustable, with a pre-set temperature of 120°F that can be increased to 140° by an installer.

It is a compact sized unit which makes it easy to install in a variety of spaces, and its advanced technology ensures that it only heats water when necessary to conserve energy. Additionally, this model is compatible with Rinnai’s full line of digital controllers and is certified for installation in manufactured (mobile) homes as well.


Flow rate: 6.5 GPM


Power output: 150,000 BTU


Dimensions: 17.5 x 30 x 13 inches


  1. Energy star approved
  2. Affordable
  3. Compact


  1. Requires additional kit to install


best condensing:

By Brighnessguru industrial experts.

Rinnai RU160iN Condensing

Rinnai RU160iN Condensing Tankless Hot Water Heater

Among tankless water heaters, the Rinnai RU160iN Condensing Tankless Hot Water Heater is a top-of-the-line option for homeowners looking for an efficient and reliable way to heat water. With a capacity of 9 gallons and a powerful flow rate of up to 9 GPM, this tankless water heater can provide as much hot water as required.

One of the standout features of the RU160iN is its energy-efficient design. Also, among other tankless water heaters by Rinnai, the RU160iN is also equipped with Circ-Logic technology, meaning you do not have to wait for piping hot water, making it one of the best tankless water heaters.  One potential downside is that this water heater requires professional installation, which may increase the upfront installation costs. 


Flow rate: 9 GPM


Power output: 160,000 BTU


Dimensions: ‎22.05 x 14.76 x 33.86 inches


  1. Unlimited hot water flow
  2. High flow rate
  3. Large heating capacity
  4. Suitable for indoor installation
  5. Safety features


  1. Professional installation recommended
  2. Limited warranty for labor


best RATED:

By Brighnessguru industrial experts.

Rinnai RL75iP

Rinnai RL75iP indoor tankless water heater

The Rinnai RL75iP is a high-efficiency, non-condensing indoor tankless water heater that offers advanced technology for your hot water requirements. With a flow rate of 7.5 GPM, this water heater can provide sufficient hot water for up to 5 fixtures at once, making it ideal for two- to three-bathroom homes.

This tankless gas water heater is designed to be extremely compact, taking up the space of a small suitcase and allowing you to reclaim valuable floor space in your home, making it worth considering compared to tank water heaters. It can also be made even smarter with a Rinnai Controlr for WiFi connectivity (not included). Experience clean, reliable hot water at a consistent pre-set temperature, energy savings with this easy-to-install water heater.


Flow rate: 7.5 GPM


Dimensions: 17.5 x 13 x 31 inches


  1. Compact design
  2. High flow rate
  3. Energy efficiency


  1. Gas flow issues

You may like to check out the best tankless water heater for the whole house.

factors to account for when buying best gas tankless water heaters

1.Temperature rise

Temperature rise is the difference between the temperature of the incoming water and the hot water delivered by the tankless water heater. For example, if you reside in a region having groundwater temperature as 60 degrees Fahrenheit and your required hot water temperature is 120 degrees Fahrenheit, the heater should be able to increase the incoming water temperature by 60 degrees Fahrenheit.

The lower the water temperature, the less GPM your tankless water heater produces as it will be struggling to raise the temperature of the water.

The temperature rise is an essential factor to consider when selecting tankless water heaters, as it can affect the performance and efficiency of the unit. The lower the temperature rise of the water, the more heat energy is required for heating water, which can result in increased energy consumption and costs.

2.Power input (BTUs):

The power input (measured in BTU) of gas heaters can vary depending on the specific model and size. As a general rule of thumb, a tankless gas heater with a power input of around 199,000 BTU can effectively provide hot water for a family of four and usage of two to three bathrooms.

When determining the appropriate BTU requirement for a house, various factors such as the number of people living in the household, the type and size of the fixtures, and the climate should be considered. However, as a general guide, here is a breakdown of BTU requirements for a house based on the number of bathrooms:

  • 1 Bathroom: 100,000 – 150,000 BTU
  • 2 Bathrooms: 150,000 – 199,000 BTU
  • 3 Bathrooms: 199,000 – 250,000 BTU
  • 4 Bathrooms: 250,000 – 299,000 BTU


Tankless water heaters come in a range of sizes, and it’s important to choose one that is appropriately sized for your household. A unit that is too small will not be able to keep up with demand, while a unit that is too large will be less efficient and more expensive to operate.

4.Fuel type:

Tankless water heaters can be powered by electricity, natural gas, or propane. Each fuel type has its own pros and cons, so you should consider which one is most suitable for your home and budget.


Natural gas: natural gas tankless units are generally the most cost-effective option, as natural gas is available in gas line and typically less expensive than electricity. They are also relatively efficient compared to their electric tankless water heater counterparts, with some models having energy efficiency ratings as high as 98%.


Propane: Tankless water heaters that run on propane are a good choice for areas where natural gas is not available. They are generally more expensive to operate than natural gas models, but still more cost-effective than electric tankless water heaters.

5.Energy Efficiency:

Look for a tankless water heater that has a high energy factor (EF) rating, as this will indicate how efficiently the unit converts fuel into heat.

Warranty: Make sure to choose a tankless water heater that comes with a good warranty, as this will provide you with protection in case anything goes wrong with the unit.


Best Tankless gas water heaters can vary from $300 to $2500 in price, so it’s important to set a budget and look for a unit that fits within it.

7.Flow rate:

The flow rate of a water heater refers to the amount of water that the heater can heat and deliver to a plumbing fixture, such as a showerhead or faucet, in a given amount of time. It is usually measured in gallons per minute (GPM).

For example, if a water heater has a flow rate of 4 GPM and you are using a showerhead that has a flow rate of 2.5 GPM, the water heater will be able to fully heat the water for the shower. However, if you were using a showerhead with a flow rate of 5 GPM, the water heater would not be able to fully heat all the water, and you would experience a decrease in the temperature of the water as you shower.

The flow rate of a water heater can be affected by a variety of factors, such as the size of the heater, the type of fuel it uses, and the efficiency of the heating element. In general, larger water heaters and those with more efficient heating elements will have higher flow rates.

8.Indoor and outdoor gas tankless heaters

Like tank style water heaters, outdoor tankless gas water heaters are installed outside of the building. They are typically made of stainless steel or other weather-resistant materials to withstand harsh weather conditions such as rain, heat, and cold temperatures. They have their own venting system, which can be more complex and expensive than indoor units.

Outdoor units are best for homes or buildings that don’t have enough indoor space to accommodate an indoor unit or if you do not want to bring inside a gas line. Whereas, this is not the case with electric water heater.



Indoor tankless gas water heaters are typically installed inside a home or building, such as in a utility room, garage, or closet. They are protected from the elements and can be connected to the home’s existing gas and venting systems. Indoor units are typically more energy efficient, as they are not exposed to the harsh weather conditions.

9.condensing and non-condensing tankless models

Condensing and non-condensing tankless heaters are both tankless gas water heaters, but they differ in their operation and efficiency. Also these two variants are not available in electric water heater.

A non-condensing tankless gas heater uses a standard heat exchanger to heat the water, which results in some heat loss through the venting system. This type of tankless gas water heater typically has an energy efficiency rating of around 80%.


Condensing tankless gas water heaters, on the other hand, reuse exhaust gas by capturing the heat (that would usually be lost through the venting system in a non-condensing unit) from the unit’s exhaust gases and using it to preheat the incoming cold water. This results in a higher energy efficiency rating, typically around 90%.

Condensing tankless gas water heaters are more efficient than non-condensing units and can save you money on your electricity bills in the long term. However, they can be more expensive to purchase and install.

OUR METHODOLOGY OF CHOOSING THE best tankless gas water heater

When selecting the best tankless gas water heaters, we consider factors such as energy efficiency, flow rate, size, brand reputation, price, warranty and venting options. We also research additional technology that can save on utility bills. We consult with professionals to ensure compatibility with existing plumbing and gas lines, and take into account customer specific needs and preferences.

Frequently asked questions(FAQs):

How to replace gas valve on tankless gas water heater?

To replace a gas valve on a tankless gas heater, remove the unit from the wall, remove the knobs and cover screws, remove the cover, detach the microswitch and solenoid clip, unscrew the grounding screw, remove the ignition mounting bracket and wires, remove the gas inlet valve and water valve assembly, remove the gas solenoid and valve stem, install the replacement parts, and reattach the retaining plate and screws. Beware that this process requires basic knowledge of plumbing and gas installation.

How to install gas tankless water heaters?

Installing a tankless gas heater requires turning off the gas and water supply, draining and disconnecting the gas and water lines of a standard tank-type water heater if replacing, and installing the new tankless gas heater in a location that allows for proper venting outside, following local codes and allowing for a minimum distance from windows, doors, and other appliances.

The plumber will connect the new copper piping, install a temperature and pressure relief valve, an expansion tank, and a condensate drain line, and connect the PVC or plastic vent pipes. The plumber will then turn on the water supply, open a hot water faucet upstairs, purge air and burp the pipes, shut off the faucet, plug in the power cord, and open the gas valve to complete the installation.

How long does a tankless gas water heater last?

A tankless gas heater typically lasts around 20 years or more with proper maintenance. However, the lifespan can vary depending on factors such as the quality of the unit, the water quality, and the frequency and level of maintenance. Regular maintenance, such as flushing the unit and replacing the air and gas filters, can help prolong the lifespan of a tankless gas heater. It’s also important to note that tankless gas water heaters require more frequent descaling than electric tankless water heaters due to the mineral buildup from hard water.

Will a tankless gas water heater work without electricity?

A tankless gas heater will not work without electricity. Tankless gas water heaters require electricity to power the control system and the fan that ventilates the combustion gases. The control system uses an electronic ignition system to light the burners, so it needs electricity to function. Some models also have an electric backup to provide hot water during a power outage. Without electricity, the unit will not be able to ignite the burners and heat the water.

How to flush a tankless gas water heater?

Maintaining tankless water heaters is important, especially in hard water areas. The recommended frequency of maintenance is every 12 to 18 months, depending on usage and the size of the household. Neglecting to maintain the tankless water heater can lead to scale buildup, which can cause problems and make a mess. The process of flushing the tankless gas water heater with white vinegar is simple. It involves using a submersible pump, a standard five-gallon bucket, and a hose set. Before flushing, it’s important to check that the tankless water heater has flush kit valves installed, which are necessary for this operation. If not, call a plumber to install them.
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