Best Natural Gas Tankless Water Heaters


Why Natural Gas Tankless Water Heater

Gas tankless water heaters tend to be more expensive than electric tankless water heaters but gas types have more capacity. Some use propane and some use natural gas. Propane powered units are a little less expensive however, natural gas units are more cost-efficient in the long run.

Both gas types offer the same performance. When choosing between propane and natural gas units, you need to consider your location. Natural gas is not available in all areas. If you have natural gas supply in your city, it would be more practical to choose natural gas and you would also be helping the environment because it is lighter than propane. It is also safer in terms of explosive risks.

Best Natural Gas Tankless Water Heaters Comparison Table 2017

Takagi T-KJr2-IN-NG4.5$$6.6Stainless steel
Rheem RTG-64XLN5$$6.4Outdoor
Rinnai RL75iN4$$$7.5Direct
Rinnai RU98IN 9.8 GPM4$$$$9.8Condensing
Rheem RTG-84XN4.5$$$8.4Outdoor

How to Choose the Best Natural Gas Tankless Water Heater

There are many factors to consider when choosing which natural gas tankless water heater is right for you. Think of the size of your home and the number of people living with you. Let’s take a look at some of these important factors.

  • Hot Water Demand

    Consider how much hot water you would be needing per day. If you want to install it in a bigger establishment, there are commercial types of water heaters that might be more suitable for your demands.

  • Gallons Per Minute (GPM)

    Once you’ve determined how much hot water you’re going to use regularly, check how many gallons of hot water the heater can provide per minute. This is also known as the flow rate. If you want ample hot water for the whole house or an average sized family, 2-4 gallons per minute is ideal. If you live alone or with a partner, 1.5 gallons per minute could be more than enough. You can see this on the specifications. Of course, the bigger the GPM, the more expensive the heater is.

  • Point of Installation

    You have to make sure that there is a gas line in the part of the house where you want to place your heater. If you’re replacing an old gas-powered tank heater, this won’t be a problem.

    You can just use the same location. You might also want to think about the area of the house that uses the most water and installs it near that location. This could be your primary bathroom or near the bedrooms that have private baths; most likely the ones with showers since those consume the most water.

  • Venting

    The proper vent system is required when installing a gas powered tankless water heater. Make sure to check the venting requirements of the unit you’re looking at and the cost of the vent installation.

    Some can only be used with direct vent installation. There are units that require PVC or stainless steel venting like the Takagi T-KJr2-IN-NG Indoor Tankless Water Heater, Natural Gas. Unless you’re placing it outdoors, there are different considerations which we will look at in a bit.

  • Storage Space

    One of the big advantages of tankless water heaters from tank heaters is they take up less space. Still, you might want to check how much storage space it will take especially if you have a small bathroom. It would be great if it can be wall mounted.

  • Design

    It could be the least of your concerns but you don’t want a flimsy looking machine inside your bathroom, especially when you invite guests over. At least, choose a model with a design that goes well with your interiors.

  • Professional Installation

    Unlike electric water heaters, gas-fired units can be very risky. If there is no one in your home who has enough knowledge or proper training for this, you might want to let the manufacturer provide the installation service. Some brands would void the warranty if the installation was not done by a professional.

  • Electricity

    In some cases, your gas tankless water heater might still need electricity to function. Check if the power cord is included and how much voltage it requires.

  • Leaks

    Watch out for possible gas leaks in the near future. Of course, you wouldn’t know this before buying the heater and it is unlikely that the manufacturer will let you know either. To get a good idea if a unit is prone to leaks, it is important to read customer reviews online. See what they are saying and how long it takes before the unit starts having this problem, or any other problem for that matter.

  • Warranty

    In relation to leaks and other potential breakages on the unit, you must get a good warranty. Normally, a longer warranty is offered for the heat exchanger. Sometimes there is a separate warranty on parts and a shorter warranty on labor if included. As mentioned earlier, some makers like Navien will void the warranty if the installation was not done by a professional.

Other Considerations

  • Indoor / Outdoor

    Unlike electric heaters, gas powered tankless water heaters can be installed outdoors. This is advisable if you live in a warm climate. An advantage of outdoor installation is you wouldn’t need a venting system. But if you live in an area where the temperature reaches below freezing, this is not such a good option.


Going with a natural gas powered tankless water heater is definitely a smart choice. Keep this guide in mind and take some time to read reviews online to compare different models before making your purchase.

Further Reading on Tankless Water Heaters