Best Natural Gas Tankless Water Heaters in 2018

Wasting time reading useless gas water heater reviews online? Well, stop because we can help you choose the best gas water heater.

Below you will find detailed tankless gas water heater reviews. All of the units are from the top brands and have been tested. So, feel free to check them out and find the one that works out the best for you.

Having a natural gas tankless water heater installed in your house can help you get on-demand hot water. There’s no need for you to wait while the water warms up anymore. Simply turn the faucet and enjoy a shower with the hot water you’ve been looking forward to.

Best Natural Gas Tankless Water Heaters: Comparison Table.


Yearly Energy
Cost Saved

Average Gallons
Per Minute Heated

#2 Tankless Water Heater - Rheem RTGH-95DVLN

Highest Quality​


9.5 gallons

#5 - Tankless Water Heater - Takagi T-KJr2-IN-NG


6 gallons

#6 - Tankless Water Heater - Rinnai RL75iN


7 gallons

#6 - Tankless Water Heater - Rinnai RL75iN


1.5 gallons

#6 - Tankless Water Heater - Rinnai RL75iN


3 gallons

#6 - Tankless Water Heater - Rinnai RL75iN


6.5 gallons

#6 - Tankless Water Heater - Rinnai RL75iN


9.8 gallons

Mentioned above were some of the natural gas tankless water heaters available in the market. Read on for know more about each of the best gas water heater brand.

These heaters have provided excellent performance, and most of them come with lifetime guarantees. These companies also provide the best customer services and technological support.

All of the recommendations have been tested so take your pick to find the best gas water heater brand for your use!

Best Tankless Gas Water Heater Reviews

  • Best use of natural gas.
  • Highest quality.

* You'll can also find the Rheem RTGH-95DVLN in our ​Definitive Best Tankless Water Heaters Guide

#1 Tankless Gas Water Heater -  Rheem RTGH-95DVLN

This is because the name Rheem is synonyms with high performance, great value, and excellent features. It provides a variety of water heaters aimed to suit different people according to their varied requirements and budgets.

RTGH-95DVLN is a natural gas tankless water heater produced by Rheem which combines comfort with value making it one of the best water heaters available.

This model provides the customers with the convenience and comfort of running hot water even to homes that have large families. This model is the perfect solution to all your hot water problems.

This also helps to make it a good choice as a best gas hot water heater.

Energy efficient

This model has a stainless steel heat condensing exchanger which makes this unit 94% energy efficient. This helps you to save money and leaves a lighter environmental footprint.

This is a very safe unit as it takes into account all the safety precautions needed to operate a natural gas water heater. The electronic controls of this heater make it not only safe as well as energy efficient. 

Bright display

The self-diagnostic system of this natural gas water heater is another fantastic function that makes the service and installation of this unit very straightforward and easy.

The display panel prominently shows the maintenance codes and the temperature making it easier to keep a check.

Safe and reliable

Another great feature is the Guardian OFW Overheat Film Wrap which keeps the unit from overheating. This film wrap also protects the built-in electrical blower. The beauty of this unit is that it is a sustainable water heater.

When you buy a Rheem water heater, you can be sure of reliability and quality. They keep a regular check on all the departments of production from the supply of raw materials to the delivery of the finished product.

Their water heating products are periodically tested by certified labs and the government to ensure their high quality and safety requirements. 

Heats large quantities of water

In an average home the Rheem RTGH-95DVLN can easily run two sinks and a dishwasher and two showers all at one time because it can heat 9.5 gallons of water per minute. This even leaves you with a lot of extra hot water!

Continuous hot water supply

The best feature of this water heater is that the water stays hot once it is heated so when you shower you do not need to adjust the controls continuously. The water is not hot for one minute and cold the other.

The supply of hot water is continuous due to the superb heating of this unit. If you use natural gas as the energy source for your water heater, then this is the unit for you.

  • It heats large quantities, 9.5 gallons, of water in a minute making it possible to get hot water in multiple taps at once.
  • It saves energy up to 94%.
  • It uses natural gas as the power source which is convenient and efficient.
  • Self-testing ensures the highest quality and safety standards.
  • Installation and setup of this unit are a little laborious and complicated.
  • Initially, it might take a few moments to get hot water in the faucet.
  • First Company to Specialize in Tankless Water Heaters in the US
  • Safety is the #1 Concern
#2 Tankless Gas Water Heater -  Takagi T-KJr2-IN-NG

Our definitive Best Tankless Water Heater Guide also has the Takagi T-KJr2-IN-NG, and with good reason.

The Takagi company has been in the forefront of providing water heating solutions to millions of customers for more than 60 years. They are the only natural gas water heaters sold by contractors and plumbing wholesalers.

Environmentally Conscious

The Takagi heaters are known not only for their quality but are also popular because of their diversity. This heater will give you the best value for your money and will never disappoint you with its performance. The Takagi heaters are built on environmentally conscious standards making them one of the best heaters available.

The Takagi company has been producing water heaters since 1952, and they have been pioneers in many departments. They are the first company in America to provide high quality tankless water heaters with 95% thermal efficiency.

Their tankless water heaters are the first to have direct vent convertible feature which allows customers to convert the heater into a direct vent unit. Their heaters were the first to use air-fuel ratio rod as a unique safety device.

The people at Takagi are real industry leaders dedicated to providing the best product to their customers that are safe and environment-friendly.

Powerful Performance

The Takagi T-KJr2 is one of the smaller units produced by Takagi, but its performance is by no means lacking. It weighs 37.6lbs, with an energy component of 0.81-0.83, which is impressive but less than Rheem RTGH-95DVLN's thermal efficiency.

The maximum flow of this powerful unit is 6.6 GPM which makes this unit perfect for small homes and apartments. You can quickly read the thermostats and monitor the temperature to ensure hot water at all times.

Convenient Installation

Although it is recommended to get a survey done to find out the best water heater for you, the T-KJr2 is a very simple unit to install and setup and is suitable for almost all houses and apartments.

You can use your existing water lines, natural gas line and vents and save on installation costs. About 90% of installation is getting the water heater mounted, and the rest is connecting the provided hardware to your hardware.

The whole installation takes only a couple of hours. You mount the unit and connect the water and gas pipes, set the temperature and after a couple of minutes can enjoy hot running water.

The entire household can use hot water simultaneously and still save almost 30% on your natural gas bill.

  • This heater is made from the highest quality material making it a very solid unit.
  • It comes with a lifetime warranty.
  • You will get hot water in multiple taps with the help of this heater.
  • The air-fuel ratio rod controls the oxygen levels to make the unit safe and hazard free.
  • Sometimes you will get cold water in between hot water.
  • ISO Certified
  • Automated
#3 Tankless Gas Water Heater -  Rinnai RL 75iN

Rinnai is a Japanese company which was founded over a hundred years ago. The vision of this company is to provide its customers with the best water heaters.

It employs more than 600 engineers who work hard to produce units equipped with the latest technology and are environment-friendly. Their team of experts is dedicated to creating new and innovative products, and the Rinnai RL75iN is no exception.

The Rinnai RL75iN natural gas water heater is a top of the line product which showcases the high standards followed by Rinnai through a strong emphasis on quality in manufacturing and design.

Its thermal efficiency is more than the Takagi T-KJr2-IN-NG, making it a good contender as a best tankless gas water heater.

ISO Certified

Their production department uses precision assembly and advanced automation which guarantees perfection in their products. All their products are ISO certified, and you can rest assured that you are the best water heater there is.

High Performance

This is a solid unit which weighs 50 lbs. and has a thermal efficiency rate of 82%. It works its optimal best between 98-140 degrees Fahrenheit for residential purposes. The units come equipped with a valve kit to make the installation easier.

The water flow is 7.5 GMP which provides you incredible hot water flexibility. The greatest feature of this natural gas water heater is the flexibility in size which makes it easier to mount it in the kitchen or the washroom and place the vent directly outside.


This heater has a built-in computer board which activates the flame switch to heat the water within seconds. The blower and the gas valve automatically adjust the oxygen and gas needed to heat the required amount of water.

If you need hot water in just one tap this natural gas tankless water heater will use less gas and a lower flame, but if hot water is required in a couple of faucets along with a two or more showers, the Rinnai RL75iN automatically senses this and increases the flame to meet the demand of hot water.

Rest Mode

When you turn off the hot water tap the flame goes out, the combustion fan decreases its speed, and the unit simply goes into rest mode until hot water is required again. This ensures that the amount of gas used is only the amount needed. This is not only perfect for your budget but is also very helpful for the environment.

Before buying the RL75iN, it is important to make sure that the vent that you are planning to use is safe for this natural gas tankless water heater.

It might take a few minutes for hot water to reach the faucet initially because this is an on demand water heater but once the water is heated, it will stay warm as long as the hot water tap is open.

Make sure that your existing gas supply can provide the power needed for this unit otherwise the heater will not work to its full potential. Proper maintenance is required to keep this appliance running smoothly and safely.

This is a complicated unit so make sure that you know how to flush the system and change the filters to enjoy hot water on demand.

  • Its energy efficient feature helps you to save money.
  • It is environment-friendly.
  • Uses less gas, so your gas bill is reduced.
  • Can be mounted even in small places.
  • The company has an experience of more than 100 years making them one of the best in their field.
  • It requires a minimum flow of water to start functioning.
  • Highly portable
  • Automated shutdown
#4 Eccotemp L5 portable natural gas tankless water heater

The Eccotemp L5 tankless water heater is one of the best portable natural gas water heaters available. This unit is perfect for cabins, campsites, and also in homes.

It weighs only 13.8 lbs. which make it very convenient to store. It is very easy to set up and is perfect for family outings and picnics. It has an automatic safety shutoff timer, and this unit comes with a one year warranty.

This is a portable unit that is why it cannot be permanently installed. Instead, when not in use it should be properly drained and stored.

Energy Efficient

This energy efficient natural gas tankless water heater can heat over one gallon of hot water per minute. It is battery operated and comes with a shower nozzle and adapter for any garden hose nozzle.


This lightweight heater is easily portable and can be used to shower after a day at the beach, or to shower at the campsite, or to give a bath to your pet. Its three easy step setup makes it convenient to use it by the poolside.

This unit is very easy to set up as all the required adapters and fittings are provided by the company. You just need to connect the garden hose nozzle and the gas tank to the heater.
This heater uses automatic ignition that is why the burners start up as soon as the water flows. This eliminates wastage of water.

When you want hot water, you just need to turn on the tap, set the desired temperature and enjoy the hot water.

Temperature Range

You can choose from multiple spray settings to enjoy the water pressure that you prefer. The temperature range of this heater is 80 to 150 degrees Fahrenheit and a water flow rate of up to 1.4 GPM. The GPM is much lower than the Rinnai RL 75iN.

The water heater automatically turns off after 20 minutes as a safety precaution.

This heater is battery operated so you can use it in places where electricity is not available, for example, while camping.

  • It is easily portable.
  • Very convenient for outdoor use.
  • Battery operated.
  • One-year warranty on limited parts.
  • Automatic shutdown.
  • The temperature control is very sensitive so be sure to set it carefully so as not to burn yourself.

This expensive looking model is perfect for small homes where the required flow of hot water is low. But it isn’t as portable as the Eccotemp L5 portable natural gas tankless water heater.

Highly Efficient

This revolutionary designed water heater has an efficiency rate of 89% making it one of the best natural gas water heaters available in the market.

This unit has a built-in flow meter sensor which ensures that the temperature of the water remains constant. This unit is also energy efficient as it uses 1.07 Amps when in operation and only 2 watts when it is not working.


The black gorilla glass casing gives this heater a very sleek look. It also has a safety feature of child lock.

Easy to Use

Whenever you want to change the temperature of water, you will need to hold the child lock for three seconds before you can modify the temperature. You can easily adjust the temperature with the help of touch screen controls. The LCD temperature display prominently shows the water temperature and flow rate in GPM.

You can easily install this heater with the help of stainless steel vent kit provided with this heater. This contributes to reducing installation costs.

  • Child lock technology makes it a very revolutionary design.
  • It is energy efficient.
  • Installation is easy and inexpensive.
  • Best for small houses and holiday cabins.
  • Not suitable for houses at higher altitude.
  • For Small Establishments
  • Impressive Warranty
#6 Tankless Gas Water Heater -  Noritz NRC661-DV-NG

This unit is the perfect unit for small houses. This gas fired tankless heater weighs 38 pounds and can hold up to 0.2 gallons of water. But the design isn’t as sleek as the Eccotemp I12-LP Indoor Natural Gas Tankless Water Heater.

This heater by Noritz in such a way that it heats water when required using natural gas, however, for ignition the unit uses electricity.

With electricity, it powers its electronics and helps to prevent the internal components from freezing.

Optional Remote Control

The NRC661 comes with a very basic temperature control; however, you can also get the optional remote control that comes with a digital easy to read display.

The heater makes use of a direct vent kit made out of CPVC or PVC pipes, but if you want to mount your heater on a wall that is non-exterior, then you can use a non-direct vent conversion kit.

This indoor heater heats up to 6.5 gallons of water in a minute. The company has been known for coming up with exceptional innovations for more than fifty years, thus making this unit a great purchase.

Energy Efficient

Another great feature of this unit is the fact that it can help you to save around 93% of the money you spend on heating water yearly. You can either use it with propane or with natural gas; the amount of cost saved remains the same.

Impressive Warranty

This unit comes with a 12-year warranty, ensuring the user’s ease. The heater is equipped with numerous features that make it more durable. These features include lightning protection devices, flame sensor, freeze protection, overheating protection devices, temperature control lock, fan rotation detector, and condensate overfill detector.

  • Save up to 93% energy cost
  • Easy installation
  • Excellent PVC venting
  • Affordable
  • Draws a considerable amount of electric power
  • Doesn’t make noise
  • Excellent quality
  • Compact
#7 Tankless Gas Water Heater -  7. Rinnai RUC98iN Ultra Series

This is an indoor natural gas heater that is ideal for both commercial and residential applications. It can use natural gas or propane as well to heat the water and comes with numerous venting options.

Compact Design

Despite having a compact and sleek design, the Rinnai RUC98iN isn’t lightweight at all. The exterior is made out of gunmetal grey and has a few control options on the lower part of the front panel.

These control options include gas control buttons, power button, an easy to read digital display, and control buttons for the temperature of the water.

With this unit, you can control the temperature of the water and can also lock the button that controls temperature to avoid unauthorized access. This has allowed the unit to be included in the current gas tankless water heater review list.


The venting options available for this unit include a twin pipe or concentric PVC. The unit is also environment-friendly since it complies with the nitrogen oxide emission standards.
What makes this unit even better is the water and gas supply inlets which are bigger than what most tankless gas heaters have.

Apart from being heavier and bigger than the other tankless natural gas heaters in the market, the Rinnai RUC98iN is also comparatively more powerful.

For starters, the energy factor of this unit is 0.95 whether you use propane or natural gas. This energy efficiency is even higher than the Noritz NRC661-DV-NG.

The heater is also Energy Star certified which is why it must be one of the first options that you consider when purchasing a tankless gas heater.

Last, but not the least, with this unit by Rinnai, you can heat multiple showerheads and faucets. This means that you can use it in households with multiple bathrooms without experiencing an interruption in the flow of hot water.

  • Endless supply of water
  • Save up to 95% of money
  • Doesn’t make any noise
  • Excellent quality
  • Bulky
  • Tricky to install

Natural Gas Tankless Water Heaters Buyer’s Guide

Some things to keep in mind when finding the best gas hot water heater:

1. Location

Different locations require different water heaters depending on the temperature and climate. Before purchasing a water heater, it is important to take into account the weather conditions of your city because they affect the efficiency of your unit.

Colder climates require a more powerful water heater to supply the amount of hot water needed while in warmer climates the water heaters produce more hot water gallons in a minute.

2. Plumbing System

Before buying a water heater get a survey done by a professional to make sure which unit will work best with your existing plumbing system. The installation guide provided with the heater will give you the specifications needed to make your heater fully operational.

3. Determine Flow Rate

Determine the flow rate of hot water required in your home before buying a water heater. This will help you purchase a water heater best suited to your needs.


A water heater is not only an investment in an appliance that provides hot water on demand it can also help you save on energy costs.

Natural gas tankless water heaters are the best water heaters to buy because of low utility costs, and they are more energy efficient than heaters with water tanks. They supply hot water consistently and take up less space. You also don’t have to wait for them to heat water before you can go ahead and use it.

When in the marketing for the best gas hot water heater, make sure that you buy one that is able to keep up with the water flow. Buying one with a low GPM is going to be useless for a big household. It should also be easy to maintain.

We hope that after reading through the natural gas water heater reviews you’ll be able to find the best gas water heater for yourself.