Nicolette Forbes

By: Nicolette Forbes on June 29th, 2022

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Do I Need to Upgrade My Gas Line with a Tankless Water Heater?

Tankless Water Heaters

Tankless water heaters are becoming the popular choice of water heaters for homeowners for several reasons, and one of them is the speed at which you get hot water in your home. We learned in this article here that tankless units can either be gas or electric but is it necessary to make adjustments or upgrade your gas line to have a tankless unit? Sounds like a mountain of a question to ask, right? Well, we are here to help you get through this tricky and important question. 

In this article, we will go into what a gas line is, gas line sizes, how to figure out which size you need, as well as how a poorly sized gas line can affect your tankless water heater.

Our technicians at Monkey Wrench Plumbing have been trained and certified with some of the top tankless water heater manufacturers since 2007. We have helped and serviced thousands of customers with their hot water needs, and now we want to help you! 


What Are Gas Lines?

Gas lines are the pipes that funnel natural gas from the supply system into your home, including your heating system and tankless water heater. 

Exposed gas line going into a home 

Tankless water heaters are water heaters that heat the water on demand, and unlike conventional water heaters, they do not rely on storage tanks. Conventional water heaters take water from the supply line, heat it, and store it in the tank for you to use. But those are not the only differences between a conventional and tankless water heater. Read this article here to learn more about the differences between the two water heaters, along with their pros and cons, to understand which is the better option for you. 

Both tankless and conventional water heaters have gas water heater models and electric ones. However, tankless water heaters have greater demand and usage of gas compared to regular water heaters since hot water has to be supplied within a short period of time. This requires your gas line to have enough gas pressure to accommodate the needs of your tankless water heater.

To do so, the gas line should be appropriately sized so that enough gas is supplied to the water heater. 


What size gas line for a tankless water heater? 

When it comes to gas lines and tankless water heaters, size does matter. 

We recommend that the gas line size for your tankless water heater be ¾-inch. However, if the length of the gas line is short enough, a ½ -inch gas line would work too. 

While you can do it yourself, we also recommend that you have a technician come out and check if you have the proper size gas line for a tankless water heater. While installing a tankless water heater, you must make sure your gas line size meets the local gas line rules and codes as well. This will vary depending on what city you are living in.

A technician working on a tankless water heater

What happens if my gas line is too small for my tankless water heater?

If the gas line is too small for your water heater, it could present many negative effects on your tankless water heater and prevent it from functioning properly. Some of the drawbacks of using an undersized gas line for your tankless water heater include:

  • Poor performance

If the gas line is too small, it could lower the efficiency and performance of your water heater. Not only will it heat the water at a much slower rate, but a small gas line can also end up producing soot, causing the burner to be exhausted and form condensate (or liquid) in the furnace or boiler.

  • Corrosion of gas lines

A small gas line would result in the furnace or boiler forming condensate. This condensate, along with the air, could result in corrosion in metallic gas pipes as they are vulnerable to rusting. If the rust happens, not only will your water heater stop functioning properly, but also expose you to fire hazards.

  • Form toxic fumes

Soot formed at the furnace or boiler could result in clogging the burners, which would prevent proper combustion. This can produce toxic exhaust fumes, which have high health risks if they enter your living space.

  • Gas shortages

A small gas line would form negative pressure in the gas line, which would cause the tankless water heater to work at a lower gas pressure. The tankless water heater would then try to take in more gas to make up for the drop in pressure which could create gas shortages in other gas-reliant appliances. 

We recommend a larger gas line to not only maintain gas pressure but also to ensure a good volume of the gas passage.


Do You Need To Upgrade Your Gas Line?

We recommend that your gas line is anywhere from ¾-inch to a ½ -inch for your tankless water heater to function properly. If your gas line is too small, you can run into several problems, including early breakdowns with your tankless water heater, gas shortages, and corrosion of your gas lines. Your tankless water heater is an investment, and you want to protect that investment by making sure you have the proper size gas line for your tankless water heater. 

Wondering what size tankless water heater is right for you and your home? Check out this article here to walk through the steps to determine which size tankless unit is best for you! 

When it comes to tankless water heaters, Monkey Wrench Plumbing wants to set you and your home up for success. If you live in the Los Angeles area and have any other questions regarding tankless water heaters or your plumbing needs, you can call us at 310-853-8690, and one of our call center representatives would be happy to help you.