A Water Heater is common appliances for both residential and commercial use, especially the winter season. Tankless Gas Water heaters are popular among homeowners cause of their unlimited hot water supply with energy-efficiency design.

There are a number of Tankless Gas Water heaters available on the market. May it is a bit difficult to select the best one. To make it easier for you, we made a list of top tankless gas water heaters.

Here you will walk through a comprehensive guide to select the best water heaters for your use. Get ready for all the information about Gas Tankless water heaters that you need to know for better purchase.

Best Gas Tankless Water Heater

According to water heater details and users review, we’ve made a list with top 10 best tankless water Heaters. Let’s try to choose the best one for your use.

  1. Rinnai RUR98iN indoor Gas Tankless Water Heater

Rinnai RUR98iN

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • Consist of innovative technology
  • Temperature rise between 50 – 70 Degree Fahrenheit
  • Dual Heat Exchangers with Maximum efficiency
  • Energy Factor: 0.96
  • 73 Lbs in Weight
  • 5 x 10 x 26 inches in size

The Rinnai RUR98iN is the first choice in our round-up which is the best tankless water heater with the highest flow rate. In short, this model provides maximum output with multiple features in a small space. First of all, It is a powerful heater with dual heat exchanger that is capable to rise 60 degrees F temperature. That makes it perfect to supply hot water in your entire home with 60 F temp rise even in the cold climate.

There is an innovative technology on this heater unit which capable supplies endless hot water with a maximum flow rate of 9.8 Gallon per minute. Here you can set the Recirculation pattern according to your water demand schedule, it will supply the hot water when you need it. And it offers both concentric and PVC venting system, which is a great offer to vent and out the exhaust gas.

At last, this Rinnai model is super energy-efficient with dual heat exchanger, which saves up to 15% of your water heating bill. If you are afforded to buy the Rinnai RUR98iN Gas Tankless Water heater, it will be the best investment for next 20 years.


  • High Temperature rise of 60 degrees Fahrenheit
  • High Flow-rate of 9.8 GPM
  • Condensing unit with dual heat exchanger
  • Highest energy factor of 0.96


  • Expensive for several users
  1. Rinnai RUC98iN Indoor Gas Tankless Water Heater

Rinnai RUC98iN

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • Concentric or PVC venting option
  • Uniform Energy Factor: 0.92
  • Maximum power output: 199,000 BTU/hr
  • 82 Lbs in Weight
  • 10 x 18.5 x 26 inches in size

Wherever you live, The Rinnai RUC98iN is the ideal Tankless water heater for any climate including the cold weather. It is powerful with advanced heat exchanger and maximum power output of 199,000 BTU that provides 60 degrees F rises hot water even cold weather.

As the best tankless water heater, this model is designed for natural gas with the indoor installation. There is also a propane gas water heater with an outdoor stainless steel version. This indoor model is capable to supply the hot water with maximum flow rate of 9.8 gallons per Minute, which fulfill your entire home water demand.

Though it is one of the expensive models in our list, it deserves it with advanced features and technology. If we compare the Rinnai RUC98iN model with another water heater model, it will become one at the top of 5 gas water heater.

It consists Wi-Fi enable a system that allows to changing and monitoring the settings. Here you can make a recirculation pattern with your need. That supplies hot water when you need it. With multiple features and facilities, the Rinnai RUC98in is a great choice for your home.


  • It is great for both of climates
  • Maximum water flow of 9.8 GPM
  • 12 Years warranty on Heat Exchanger
  • Compact design saves valuable space indoor
  • Suitable for large home


  • May it is Expensive for several buyers
  1. Rinnai V75iN Tankless Water Heater

Key Features:

Rinnai V75iN

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • Digital Control system
  • Energy Factor: 0.82
  • Temperature Range: 98 – 140 Degree F
  • 04 x 9.27 x 26.9 inches in Size
  • 6 Lbs in Weight

The Rinnai V75iN is a lower price Gas Tankless Water Heater on our list. We think this is a great option to buy for your average household with Maximum hot water flow rate of 7.5 GPM.

Like the Best Tankless water heater, the Rinnai V75iN is compact in size and lightweight with multiple features in this unit. Though we think it is a large water heater, it’s 14.04 x 9.27 x 26.9 inches in size which takes a small area in your home. There is an eye fascinating design with the best color combination. That will  look good in your house instead of you install it next to another white appliance in your room.

With the maximum hot water flow rate, this heater is ideal for the average household in any climate. It is capable to run two showers at a time or a laundry and other faucets like a sink, tap, or anything else. You can choose a comfortable temperature between 98 -140 degrees Fahrenheit. And there is a temperature lock to prevent any accident on this water heater unit. Moreover, it allows to schedule and control through an R2.0 mobile app.

With the advanced heat exchanger, it is durable for a long time. It also bought a long-period warranty in the full unit. As 10 years in the heat exchanger, 5 years on parts, and 1 year on labor.


  • It can be control and Schedule with R 2.0 Mobile app
  • Maximum Flow rate of 7.5 GPM can be able to fulfill your hot water demand
  • You can set a comfortable temperature among 98 -140 F through Temperature Range
  • Energy-efficient
  • Long Period Warranty of 10 Years on Heat Exchanger
  • Lower price


  • It can’t be used on Outdoor
  • It’s a bit slower to Respond than other Tankless Water Heater
  1. Rinnai V75eN Gas Tankless Water Heater

Rinnai V75eN

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • Maximum power output: 120,000 BTU
  • 4 Lbs in Weight
  • 6 x 14 x 24.3 inches in Size
  • Digital Controllers available

Rinnai V75eN is one of the most popular water heaters among the Rinnai V series Tankless Water Heater. If you are looking for an outdoor water heater with maximum flow rate for your entire home, this is a solid solution for you.

There are multiple features and facilities includes in a classic and compact design. It consists of an eye fascinating view with a simple design and color combination. Its 120,000 BTU heating capacity is capable to supply hot water at 120 degree Fahrenheit with maximum flow rate of 7.5 GPM (Gallon per Minute). Thankfully it meets California and Texas NOx Emissions Standards which help you to digitally control.

This water heater is ultra-lightweight and 9.6 x 14 x 24.3 inches in Size which takes a little space in your home. That’s a very beneficial feature for you. Moreover, it is an outdoor installations water heater that is very easy to install by one. You can install it yourself without hiring a professional. This Water heater is reliable for a long time and it has bought 10 Years warranty on heating exchanger and 5 years on parts.

With these features and facilities, the Rinnai V75En Gas Tankless Water Heater will be pleased you by fulfilling your hot water demand.


  • Compact design saves your valuable space on your home
  • It is ultra-lightweight with multiple facilities and features
  • Maximum Water flow of around 7.5 GPM
  • High energy factor about 0.82
  • Eye fascinating design with white color
  • Long time warranty of 10 Years on Heat exchanger, 5 Years on Parts and 1 Year in Labor service


  • Only for Outdoor Installation
  1. Rinnai Ru199iN Sensei SE Tankless Water Heater

Rinnai Ru199iN

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • It consists of Circ-Logic Technology
  • Maximum power output: 199,000 BTU
  • 5 x 11.45 x 31.3 inches in size
  • 64 Lbs in weight

If you have a large household and you love to use innovative technology, the Rinnai Ru199iN is a great choice for you.

This water heater consists of the Circ-Logic technology which allows you to set a circulation pattern according to your need. It will provide hot water when you need it. With maximum water flow of 9.5 GPM (Gallon per Minute) it can be able to supply the hot water at multiple bathrooms, kitchen, and any other faucets at a time. With this highest flow rate, this water heater is super energy efficient that saves a large amount of energy bills than any other water heater.

This Model consists Wi-Fi monitoring system so that your Rinnai service provider can monitor your water heater efficiency and issues the address remotely. Though most of all users hire professionals to install the water heater unit, some users reviewed it is simple and easy to install which saves a thousand or a couple of thousand dollars labor cost.  

If you can buy the Rinnai Ru199iN gas Tankless Water heater that will become the best investment for your home.


  • 8 GPM output flow supply endless hot water in your entire home
  • 10 Years Warranty (Heat Exchanger), 5 years warranty (Parts) and 1 Year Warranty (Labor)
  • Circ-technology allows to you set recirculation patterns that helps you get hot water on your need.
  • It is a Super Energy-efficient water heater


  • The hot water takes a bit of time to reach the faucets.
  1. Nortiz NRC66DVNG Indoor Gas Tankless Hot Water Heater

Nortiz NRC66DVNG

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • 39 Lbs in Weight
  • 7 x 13.8 x 23.6 inches in size
  • Advanced heat exchanger
  • A wide array of Venting option available

If you want to buy a lightweight and small Gas tankless Water Heater, The Nortiz NRC66DVNG is an ideal option for you. This is a fully condensing water heater with an advanced heat exchanger and well-built quality.

With advanced heat exchanger and maximum power output, the water heater is capable to supply endless hot water on your demand. It is a super-efficient water heater instead of having powerful features. There is a facility to vent with schedule 40 PVC pipe and fittings. With these features, it has low-Nox advantages.

This Nortiz NRC66DVNG is durable with heat exchanger and parts. Moreover, it has bought a large time warranty on Heat Exchanger about 12 Years, 5 Years on Parts, and 1 Year warranty on labor. If you afford to buy it, it will be pleased with its fluent service for a long time.


  • Small and Lightweight tankless water heater
  • High Energy-efficiency unit
  • Easy to Install
  • Schedule 40 PVC piping and fittings venting process vent out exhaust gas
  • Long-period warranty of 10 Years on heat exchanger


  • It is only an Indoor-Unit
  1. Gasland BE158 Outdoor Portable Gas Water Heater

Gasland BE158

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • 62 Lbs in Weight
  • 8 x 6.1 x 17.3 inches in size
  • Maximum power output: 41,000 BTU

Gasland portable gas Water heater from Gasland is the last product in our round-up. In short, there are a lot of features in a place which makes it better than other one.

First of all, it has several safety systems such as anti-freeze protection, flame failure device, as well as overheating protection. These all ensure your family’s safety. If the water pressure crosses 110 psi the heater will automatically decrease it to prevent accidents or any kind of accidental change in your heater unit.

It features a lightweight design in a compact unit that makes it very easy to carry and mount it. There are several mounting brackets in the back site and top of the water heater which takes a few minutes to install it.

In the terms of energy saving, this unit saves up to 11.5% energy with latest energy-saving technology. Moreover, it provides excellent customer service with a professional team. If you are able to buy the Gasland BE158 portable gas water heater in low price, it will please you to supply hot water on your demand.


  • Several safety systems in a place
  • Multiple features in a compact and lightweight design
  • Water and heat flow rate is fully Adjustable
  • Energy-efficient
  • Excellent Customer Service


  • Low flow-rate about 2 Gallon per Minute
  • Its instruction manual doesn’t refer to the uses system of this unit.
  1. Rinnai RL94eN Natural Tankless water Heater

Rinnai RL94eN

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • Circ-Logic Technology includes in this unit
  • Wi-Fi Monitoring system available
  • 2 Lbs in Weight
  • 02 x 10 x 22.99 inches in size

The Rinnai RL94eN is another product from Rinnai. This is a unit of top 10 Gas Tankless water heaters with maximum flow rate.

There are advanced features and modern technology included in this heater unit. It has consist of Circ-Logic Technology to set the recirculation pattern on your water uses habits. It will supply hot water automatically when you need it. With maximum power output the water heater capable to supply endless hot water for your entire house. You can run multiple shower, faucets or a washing machine at a time with maximum flow rate of 9.4 GPM.

With Maximum power output and high flow rate, the Rinnai RL94eN is a high energy efficient water heater among the Rinnai RL series. It is durable for a long time with a heat exchanger and parts. Also, it has bought a long period of warranty time (12 Years on Heat Exchanger). With these modern features and facilities, this model is great option to buy in affordable prices.


  • It saves up to 80% energy
  • Easy to set up and install
  • Excellent view with a compact design
  • Long time warranty
  • High flow rate


  • You have to take maintenance at least once in each year.
  • May it is Bulky for several users
  1. Takagi T-H3_DV-N Water Heater

Takagi T-H3_DV-N

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • Computerized safety features provide safe use
  • Maximum power output: 199,000 BTU
  • 59 lbs in Weight
  • 75 x 17.75 x 22.5 inches in size

Takagi TH3DVN is the most energy-efficient gas water heater in our round-up. According to the energy-saving guide, this water heater has gained an energy-star label from the US government. That’s a label only a few water heaters are able to obtain.

This water heater is lightweight with a compact design. Thankfully, it has an eye fascinating design with the best color combination. You can install it indoor next to another white appliance. There is an advanced heat exchanger that is capable to supply endless hot water on your demand. With a maximum power output of 199,000 BTU, it can supply the hot at 100-185 degrees Celsius temperature range. 

Apart from this, there is a primary heat exchanger includes in this unit. That transfers the heat better than the stainless one and makes it an energy-efficient water heater. At last, this unit contains multiple safety features such as overheat protection, freeze, troubleshooting diagnostic, and surge protection. They will prevent heat accidents or other changes with the unit. With the features and facilities, the Takagi TH3DVN is a solid option to you.


  • It provides Endless hot water supply with high water flow
  • Maximum Energy-efficiency
  • Maximum water flow of 10 GPM
  • Best safety protection
  • It has ultra-low NOx Emissions
  • Affordable price with long time warranty


  • It is difficult to install cause of condensing unit
  1. Eccotemp FVI-12-Ng Gas Tankless Water Heater

Eccotemp FVI-12-Ng

Bosch Tronic 3000 T Electric Water Heater with Mini Tank

Sub Title

  • Digital Display available
  • Electronic ignition system also includes
  • 29 Lbs in weight
  • 25 x 6 x 24.75 inches in size

If you are searching for a small and lightweight tankless water heater with maximum flow rate, the Ecotemp FVI12NG is a great choice for you. This is the last product on our list. In short, this water heater is suitable for a small size house or office. There are digital features and latest technology includes on this unit such as the digital temperature display.

The Ecotemp is 15.25 x 6 x 24.75 inches in size with lightweight design. It can fulfill your hot water demand with the maximum flow rate of 4 gallons per minute. It contains a digital temperature display that is easy to read and control. It is very easy to install an indoor a few minutes. Moreover, there is a safe electronic ignition system to connect a power supply from 120 V electrical outlets.

Several users complained about its durability and short time warranty of 2 years. With the features in a lower price, the Ecotemp will be pleased with the hot water supply at a uniform temperature.


  • Lightweight and compact Design
  • Easy to read digital display
  • Simple installation system
  • Both gas and electric supply system is available


  • Short time of Warranty period
  • Low GPM
  • Low energy-efficiency

Gas Tankless Water Heater Buying Guide

Why you should choose a gas tankless water heater

Forget electric models if your budget is limited. Smaller units, sold starting at $ 500, will be unable to adequately supply more than one faucet. To meet the needs of a family, a very powerful model is necessary (at least 28 kW), but at a cost quickly rising to $ 3,000, not to mention any additional costs for a particular electrical connection.

Indeed, such power may require a complete review of your electrical installation. Electrically heated homes normally have an input of 200 amps at a voltage of 240 volts, which corresponds to a maximum power of 48 kW (200 x 240 = 48,000). With an instantaneous water heater, you will certainly have to go to 300 amps and replace the electric cable connecting your distribution panel to the water heater, work that presents a significant additional investment (at least $ 2,000).

Under these conditions … choose a gas model. The average additional cost is $ 525 according to a study conducted by some officials, but in general, count between $ 600 and $ 1,800 to purchase depending on the water heating capacity.

How to choose a gas tankless water heater?

Tankless gas water heaters can operate without electricity, but they are mostly low-end using air inside the house rather than outside air for combustion. This type of system is not recommended because it draws in and dissipates heat from the house, and because an unsealed combustion chamber can present a risk of carbon monoxide poisoning in the event of depressurization or backflow of combustion gases. .

The more upscale models operate by sealed combustion: a first pipe supplies the burner with fresh air from the outside while another ensures the discharge of combustion gases (several configurations are possible). The devices operating thanks to an ignition pilot are a little less efficient because there is a slight but constant consumption of gas to keep the pilot on, even when not in use.

In Europe, where the instant gas tankless water heater has been in common use for over 25 years, users have developed the habit of switching off the pilot when use of the water heater is not required. However, manufacturers now offer electronic ignition devices that eliminate this drawback: make sure the selected model has it. Finally, for second homes or those located in remote areas, an instantaneous water heater running on propane gas seems ideal.

A better water heater can be an excellent option in your daily life, so you must not only consider the level of quality, but also the flow, pressure and other types of factors to choose the one that best suits your needs.

Because the living conditions of each family are different, only the most suitable one can be considered as the best water heater for you. Here are some factors to consider to get the best water heater:

1. Flow

Since there is no tank installed in the heating machine, you do not need to worry about the capacity of the heating machine, but still, you must estimate the amount of water for your daily use. And decide for what conditions you are going to use it, be it for commercial use and for large family use. Then you can choose the right flow depending on your applications.

For the dishwasher, 1-2.5 gallons per minute of water are needed, and the bathroom faucet needs 1.5 gpm, while the kitchen faucet ranges from 3-5 gpm. To use two toilets at the same time in winter or cold areas, you need to get one that reaches at least 6 gpm.

2. Power supply

If you need to use it for whole house use and support two or three showers at the same time, you can use propane hot water, but for small studios or points of use, we recommend the electric type.

3. Location of the house

The location of your home is also an important factor that you must consider. If you live in warm areas, you can choose based on the exact flow rate. Cold climates will have a great effect on water temperature and flow rate as it can drop 2-3 gpm in cold areas, therefore when purchasing a water heater for cold weather areas you should consider the factor y choose a relatively high flow rate.

4. Energy efficient

Gas types are more efficient than electric types, especially during a long period of use, the thermal efficiency reaches 90% for some types. Electric water heater can also save 60% energy cost.

For some gas models, condensing technology is equipped, which recovers unused energy in non-condensing types and greatly improves efficiency and reduces greenhouse gas emissions.

5. Installation costs

Installing the water heater is quite simple and straightforward, but it has special requirements on pipes, lines, and pressure. If you need to replace a water heater with a new one, you can change the entire wiring system if it is not compatible with the old one. And for professional installation, you also need to pay a large amount of money. 

6. Indoor and outdoor installation

Still worried that there isn’t much space at home? You can then choose an outdoor type. It can be installed outdoors and therefore does not need ventilation installations. But remember that you must get a protective device to prevent damage from harsh external climates.

Why buy gas tankless water heaters?

Environmentally friendly: compared to other fuels derived from oil, gas water heater is much cleaner; emits 45% less carbon than other still water heaters.

It is more efficient: compared to other water heaters, such as electric type, the gas water heater is 3 times more efficient and there are up to 90% of usable energy in use. The usable energy of other types reaches around 80% or even less.

It is more economical: The entire cost of using the gas water heater is relatively low but it is more powerful. Based on professional testing, a gas water heater can save 30% less money on your heating bills each month.

It is more reliable: Natural gas is transferred and used through underground pipes; you can use it in multiple applications at the same time. That is why it is more reliable and safe.

 Types of gas tankless water heaters

With different installation points and applications, the types of gas tankless water heaters are different; They can be divided into indoor, outdoor, full home type and portable. 

Here we will give you a fundamental difference and characteristics of each type. And for each model, you can directly choose the most suitable one based on your needs.

1. Place of installation

Indoor Gas Water Heater: Indoor gas water heater refers to the heating machine that was installed indoors, either in the bathroom or kitchen or directly under the sink. The key to the indoor heater is ventilation; Vent kits need to be installed together with the machine for gas to escape. If installed at the point of use, it only takes a few seconds for the hot water to flow, mainly it reduces the waiting time and saves a lot of money. 

Outdoor Water Heater – Outdoor gas water heater, as the name suggests, is installed outdoors. But to reduce waiting time, it is often installed outside of the bathroom or kitchen wall. No ventilation is needed. But you need to make sure that it is well protected against severe weather conditions and does not put anything flammable in the machine. There are still many other things to consider in an outdoor gas water heater.

2. Size

Gas water heater for the entire household: For take a bath, wash clothes and hand washing at home, hot water is needed all the time. Therefore, you need to get a whole house gas water heater to handle the hot water for both the shower and the taps. The flow of the whole house type is relatively large and it is much more powerful. 

Portable gas water heater: portable gas or the small gas water heater, refers to the machine that is small and light. It can be transported and used outdoors in camping or installed in RV. The flow rate is quite small and meets the basic needs of hot water use. And of course, the price of the portable gas water heater is low.


Although electricity is also an option to power your heater, gas is the most popular option for water heaters. Whether you choose natural gas or propane options, you’ll get instant and efficient water heating. 

Saving money is not the only benefit. They also do not harm the environment since the energy expended is considerably less than with a classic model. In addition, most models are recyclable, which is another way to contribute to the environment.

Gas tankless water heaters are space savers. The fact that they do not require a tank to store water allows this. You can hang it on the wall, place it behind the stairs or choose the desired location so that you have an optimal balance between aesthetic value and functionality. 

Gas water heaters are also a convenient fit for compact homes where every square foot is important.

How to install a gas tankless water heater  

Once you choose the desired unit, you must be careful in the installation. Setting everything up correctly is essential as it ensures the safety and maximum efficiency of the unit. Here is an overview of the steps to consider during the installation process:

Choosing the location: Before purchase, consider whether it will serve as an internal or external heater. A professional will begin by inspecting your property and trying to find an optimal area to place the unit. The choice will depend on the size of the property and other features, as well as where you need hot water. Ventilation options will also be a primary consideration to ensure optimal safety. If possible, go with the same location as your old heater which simplifies installation.

Install it on the wall: If you choose to install it on the wall, be sure to follow the detailed instruction manual and use all the necessary parts.

Connection to the gas line: make sure that the gas pressure is in line with what is specified on the nameplate. The pipes you use should be no smaller than the diameter of the heater connections. Use the soap and water solution to check for gas leaks. If you have no prior experience, we suggest that you hire a professional to take care of the installation.

Now why is ventilation a prime consideration when installing a water heater? The reason is the optimal indoor air quality and the safety of those who are inside the property. If you are installing the heater outdoors, you don’t need to worry about ventilation. However, indoor heaters produce carbon monoxide and other dangerous gases.

The general things to keep in mind is that the exhaust gases must be vented and the intake of fresh air must be ensured. When choosing a ventilation option, you can go with power and direct ventilation. The power option is to fit an exhaust vent to get rid of hazardous gases. Keep in mind that the length and number of elbows should be kept to a minimum for optimal ventilation.

When it comes to running the unit, you will install exhaust and intake vents. You should opt for this option when there is not enough fresh air naturally ensured. An intake vent will draw outside air through the vent.

How to maintain your gas tankless water heater properly

Okay now you know more or less about gas tankless water heater,what it is ,how to use it,why you choose gas tankless water heater and so on .

In this section we will cover some important fact about gas tankless water heater,so that you can properly maintain your gas tankless water heater.

  • Always off the power source of your gas tankless water heater.
  • Remove the caps of both hot and cold water valves.
  • Connect hose lines correctly with the three valves.
  • When you try to clean the gas tankless water heater do not use chemical products, you can use white vinegar for optimal result.
  • Regularly perform the flushing and draining following manufacturer guidelines of the product.

Some FAQ about Gas Tankless Water Heater

  • Can i save money using gas tankless water heater ?
  • Ans: Yes you can,it depends on your gas tankless water heater type as usual model .From 5% to 69% percent of your water heating bill.
  • I am in a high altitudes places ,do it affect my gas tankless water heater ?
  • Ans: In short yes it can ,if you want to read more about high altitudes and gas then read more here —– out going links .
  • One tankless gas water heater is enough for entire home?
  • Ans: For some model it is enough for some it’s not, but the ma in factor is how much hot water supply you need for daily basis.