5 Best Gas Tankless Water Heaters: Reviews and Buying Guide

You are most propably here to get the best gas tankless water heater for the money. Gas Tankless Heaters are one of the popular heaters in market due to the numerous advantages associated with them. Besides cost-efficiency and savings on energy, these heaters produce instant hot water supply at a consistent rate. The compact design of these heaters makes them an ideal choice for tight spaces.

The supply of water with these heaters is not limited by the tank capacity. Hence all you need the best gas tankless water heater to enjoy a quick hot shower on a chilling day. Being so many players in the market offering several heaters makes the process of choosing an ideal one complicated.

Hence, we offer a comprehensive guide on the best Tankless water heaters which lists the Best 5 choices available on the market with their detailed review. Also, we have prepared a guide which lists all the factors which you should consider to find ideal option for you.

Best Gas Tankless Water Heater For The Money

Rinnai RUC98iN Ultra Series

The first in the list is a water heater from Rinnai. It is an indoor gas tankless water heater which can be run using natural gas or propane. Complying to the nitrogen oxide emission standards, this efficient heater boasts a sleek design which is space-saving. It can be flexibly installed anywhere within the house.

Control section is available on the gunmetal grey exterior of the heater which includes water temperature buttons, digital display and power button. It allows the user to lock the temperature button to refrain any unauthorized access.

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Compared to other gas heaters, it has larger inlet and outlet provisions, making it a powerful heater. Multiple showers and faucets can be supported with this heater without interruption. With the minimum activation rate of 0.4 gallons, it offers the flow rate as high as 9.8 GPM.

It is capable of providing a heating range between 95 to 140 degrees Fahrenheit which is considered as an excellent range for a heater of this capacity. It is an environment-friendly heater which saves energy by heating the water only when required.


  • The compact design makes it ideal for small spaces
  • This heater is Energy star certified and offers great energy savings
  • It does not make noise and works quietly
  • As the water does not get stored in the heater, there are minimal chances of scale and rust
  • It ensures unlimited hot water supply
  • Wait time for hot water is minimal


  • There are water heater available which are compact than this one
  • Not meant for the people looking for budgeted water heater
  • It is difficult to install


Takagi T-KJr2-IN-NG

This compact heater has a gas input if 1,40,000 BTU , making it ideal for residential usage, especially if it is fixed at a certain level. With a flow rate of 6.6 GPM at a temperature of 35°F, it has the potential to offer consistent hot water. If the temperature goes up to 70°F, the heater assures a maximum flow rate of 3.3 GPM.

In case of any operational safety issue, various codes are assigned for troubleshooting. There are various protection capabilities included in the heater pertaining to freeze, overheat and surge. Barring a few parts where the manufacturer is offering a warranty of 5-years, there is a 10-year manufacturer warranty available on this water heater.

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The warranty services are only applicable when the damage occurs under normal circumstances and while its regular usage. Any damage on account of installation defect will not be covered under warranty. Hence it is recommended to seek a professional for installation. It allows constant temperature monitoring with thermistors. It comes with a direct vent conversion kit, pipe cover, lead-free isolation valve, remote temperature controller and pressure relieve valve.


  • A resource and space saving heater with cost-efficiency
  • It offers great capacity to the users with its excellent flow rate
  • Overheat, surge, and freeze protection to extend the safety of the user
  • 10-years of manufacturer warranty
  • Great flexibility with remote and power cord control
  • This heater is ideal for high altitudes


  • Considerable lag time for the supply of consistent hot water
  • After-sale cost is expensive


Rinnai V65EN 6.6 GPM

With a flow rate of 6.6 GPM under moderate climatic conditions, this water heater works on 150000 BTU and weighs around 48 pounds. With its streamlined internal operations, it can easily be mounted anywhere in your house.

It comes with a pre-set temperature of 120°F with flexibility to adjust it between 98°F to 140°F. It comes with a detailed manual instruction which guides you about the various aspects of this water heater. The installation is easy but seeking professional help is recommended for installation.

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It is a no-fuss water heater which does a great job with its temperature-lock system. IT is easy to maintain with its advanced scaling mechanism which helps in avoiding serious damage. It comes with 10-feet thermostat wire and remote control.


  • This efficient water heater is meant for ‘whole-house’
  • It is an affordable natural gas heater
  • It is easy to install and maintain
  • It has an enhanced scale detection mechanism
  • low NOx emission level making it an environment-friendly heater
  • Minimal venting requirements being an outdoor unit


  • It is not compatible with the large homes
  • Flow rate diminishes under the very cold climatic conditions
  • It is an outdoor unit only


Eccotemp 45H-NG

It comes with a flow rate of 6.8 GPM, it is wall mountable water heater. It comes with a digital display and simple controls to ease the users with operations. It is an eco-friendly natural gas water heater which comes with white chrome coating and stainless steel interiors.

This heater has a CSA/UL certification. It is resistant to rust and corrosion due to its stainless steel made. It comes with an energy rating of 82% and has simple controls. It comes with 110-Volt UL listed power cord. It has been designed purposely for outdoor usage. It has an in-built antifreeze circuit to make it an excellent choice for extremely cold regions.

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Overall, it is an ideal choice for standard sized homes which promises to save 20% of the gas bill.


  • It is a very compact unit, making it a space-saving deal
  • Very smooth and quiet with operations
  • Quick and easy installation process
  • Being an outdoor unit, no venting required
  • Ideal for single families with 2-4 members
  • Shut-off valve, digital remote, pressure and temperature valve and ¾” NPT fittings are included
  • 5-year manufacturer warranty on certain parts and 10-years manufacturer warranty overall


  • The adjustable flow sensor is not provided
  • No energy star rating is provided
  • Users complain about the inconsistent temperature



A highly portable water heater due to its compact design and low weight, this heater claims to use the half of the gas usage compared to any standard propane gas water heater. With no electricity requirements, you just need 2-D battery cells to operate.

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It is a versatile water heater that allows adjusting the water activation flow as well as the amount of heat. It is one of the high-quality, innovative yet affordable propane gas tankless water heater. It can provide up to 1.5 GPM of water at 115°F output water temperature.

It is an outdoor unit which comes with detailed manual instruction to guide you rightly on its installation and appropriate usage.


  • It does not require any extra venting.
  • It is a multi-purpose water heater which helps in doing a variety of chores
  • Ensure endless consistent water supply
  • It comes with a CSA approved regulator and a gas hose
  • A compact heater which is light in weight
  • It comes with 5-year manufacturer warranty
  • It is designed in the USA


  • 2-D battery cells are required to be purchased separately
  • It is not suitable for extreme cold climatic conditions

Factors to be considered before choosing the best gas tankless water heater: Buying Guide

It is important to have a thorough understanding of each aspect of any tankless water heater before buying the best one for you. Here are some of the important factors which one must consider before buying a tankless heat:


The size of a heater is important to consider before making a buying decision. For large families, it is important to buy a large model with a higher flow rate which can suffice the needs of more than one bathroom at one time. If you have a small family, it is judicious to invest in a small water heater as the price of a water heater is directly proportional to the size and the features it carries.

Brand Value

Brand value plays an important role in qualifying for the quality of water heater. A well-recognized brand which is prevailing from a long time in the market is the safest deal to count upon. Most of the popular brands also offer great after-sales service which is another important point of consideration.


A heater with promising warranty periods proves to be cost efficient than the one which does not offer any warranty. Any after sales fault can dig big holes in your pocket if it is not cover under the warranty. Hence, choose a product which offers maximum warranty even at a slightly higher price point.


A ventilation kit is required by the gas tankless water heaters to emit the used gas. There are certain heaters which require special ventilation as well as PVC pipes. So, it is important to be sure about the type of ventilation services required to save a considerable amount of money on these heaters.


A heater which is energy efficient helps in lowering downs your bills and turns out to be eco-friendly as well. However, there are certain standards which are set by the manufacturers. And if you observe closely, you will find that certain heaters are more energy-efficient as compared to the other ones. Hence, count upon the heater which saves energy as it will justify your ROI in longer run.

Waiting Time

The time that hot water takes from flowing down from the pipe to the destination is referred to as the waiting time. Higher the distance, greater shall be the waiting time. Higher the waiting time, more the cold water is wasted and you will experience higher energy bills. Hence, choosing a machine which assures fast waiting time will surely save you a good amount of money in the longer run.

Flow rate

The flow rate is another important consideration which ensures the consistent hot water supply. Higher the flow rate, better it is.


The heaters with easy installation process are better choices. For complicated installations, you require some professional help adding to your overall cost. Moreover, certain manufacturers have a condition that if there is any damage to the heater during installation or the damage occurs due to faulty installation, the warranty will stand void. Hence, it is important to check the installation procedures prescribed by the manufacturer.


Although tankless gas heaters are the best choice when it comes to cost-efficiency and energy savings, choosing an ideal on for you still not an easy decision. There are large number of models available in the market with several distinctive features. It is important to choose a heater which complies with your preferences and fit your budget rightly.

Once you short-list the heater, don’t forget to check the various reviews posted online by the various existing user to understand the real-life efficiency and complication level of the certain heater.

Frequently Asked Questions

Are gas powered tankless heaters better than electric ones?

Gas tankless heaters are more powerful and able to support the multiple faucets at the same time. They also cost you less as compared to the electricity bills. They are considered safer with use and assure consistent hot water supply even in a cold climate region. However, Gas heaters are expensive than electric heaters and require ventilation.

Does the water temperature affect by the Altitude?

When it comes to gas water heaters, their efficiency losses at the rate of 4% with every 1000 feet. Hence, if you are buying a gas tankless water heater, you should consider your altitude to determine the efficiency of the heater you choose.