Can You Use A Flexible Gas Line On A Furnace? (Find Out Now!)

Heather Robbins
by Heather Robbins

Many households in the northern half of the country will have to turn on their heating systems at the beginning of October. Natural gas is one of the most cost-effective and efficient fuels for a furnace or boiler. With its benefits come questions about safety and obligations for homeowners.

While flexible connectors are able to be connected to gas piping as long as they have a shutoff valve installed, they’re not permitted to be used on gas furnaces, space heaters, water heaters, and other appliances. Always check with your regional laws on where you’re able to use flexible pipes.

In this article, we will discuss the ins and outs of flexible pipes and where they can be used so that you are aware of how it pertains to your situation. Let’s get started!

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The Gas Supply Line

The gas supply line, also known as the building line, is the plumbing that runs throughout the house. Individual appliances are served by branch lines.

The branch line finishes in a drop line, which is a vertical pipe that drops down from an overhead branch line to the appliance. If it carries gas up to an appliance from a branch line below the appliance, it’s called a riser.

Sediment Trap Or Dirt Pocket

A sediment trap or dirt pocket commonly referred to as a drip leg is normally present at the appliance connection point and consists of a nipple and a cap.

This pipe extension, which is normally at least 3 inches long, is designed to catch any water or foreign material that may be present in the gas before it enters the appliance. The solids and liquids fall into the pocket, which is just a gravity mechanism.

Downstream Pipework

The homeowner is normally responsible for the pipework downstream of the gas meter. The gas company is normally responsible for the piping upstream of the gas meter, as well as the meter itself.

Piping Materials

Steel, copper, and brass are the most prevalent materials for gas piping. In some cases, galvanized steel, copper, brass, or CSST (Corrugated Stainless Steel Tubing) can be used, but copper is prohibited by some utilities. Copper is widely used in different parts of the world.

You should be aware of what is considered acceptable in your neighborhood. Black steel piping with malleable iron or steel fittings is common. In other cases, galvanized steel is also used.


Flexible connectors are allowed to be used to connect appliances to gas pipelines. A shut-off valve must be installed at the rigid piping connection. This valve must be located in the same area as the appliance.

Accessible and three or six feet long: The flexible connectors cannot pass through walls, floors, or ceilings, and they cannot be hidden. Except for gas stoves and laundry dryers, the flexible connector length is normally limited to 3 feet.

6 feet is usually allowed for this equipment. Using nipples to splice or join connectors is frequently forbidden. Flexible connectors are only authorized in some jurisdictions for gas stoves, dryers, outdoor barbecues, and other semi-portable equipment.

Flexible Connectors

Flexible connectors may be prohibited on gas furnaces, water heaters, space heaters, and other similar appliances.

Flexible connectors are more likely to be utilized on all appliances in earthquake-prone areas because they give some protection against gas piping leakage or rupture during an earthquake. To find out what is and isn’t permitted in your area, consult your local gas code.

Thread Seal Tape

The use of white thread seal tape (often referred to as Teflon® tape) as a connecting material for steel gas piping is not recommended. Cutting oils on the pipe threads from the manufacturing process may hinder the tape from sealing.

Yellow thread seal tape is permitted in some regions. Pipe dope is favored and may be the only option available. You might wish to double-check with the gas company. Inquire about if any piping installations with thread seal tape of any color should be reported as a defect.

Bonding Gas Piping

The use of gas piping as a grounding mechanism for the electrical service is prohibited by most authorities. In many areas, however, bonding the gas piping to the electrical grounding system is required.

This is often accomplished by connecting the gas pipe to the supply water piping (assuming it is grounded) near the water heater.

We want to keep the gas piping at zero electrical potential by attaching it to the grounding system to prevent an electrical potential accumulation within it that could lead to arcing, which could ignite gas.

Common Issues On Gas Piping

On gas piping, the following issues are common:

  • No drip leg
  • Missing shut-off valve
  • Leaks
  • Piping in chimneys or duct systems
  • Improper connections
  • Inappropriate materials
  • Inadequate support
  • Rusting
  • Copper tubing not properly labeled
  • Piping in chimneys or duct systems
  • Plastic pipe exposed above grade

All of these issues have the potential to result in gas leaks and explosions.

We’ve gone over some of the fundamentals of gas pipe that home inspectors should be familiar with in order to spot potentially dangerous situations. We’ve also compiled a list of ten common symptoms associated with gas piping issues.

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Related Questions

Can you use a flexible gas line in a house?

Whatever anyone says about these pipes, you can rest assured that they are both safe and functional. When gas is fed to a cooktop, a clothes dryer, or a gas range, this brass appliance connector tubing is used in every house built today.

Where can I use CSST?

CSST is versatile, allowing it to be routed beneath, through, and alongside floor joists in your basement, inside internal wall cavities, and on top of ceiling joists in attic spaces, as well as connected to stationary equipment like water heaters.

Where can a flexible gas line be used?

CSST is a flexible, corrugated stainless steel tube that is used to provide natural gas and propane to homes, businesses, and industries.It should not be confused with appliance connectors, which are comparable flexible pipe that connects directly from the wall or floor to mobile appliances like ovens or dryers.

Heather Robbins
Heather Robbins

Heather is a passionate writer who loves anything DIY. Growing up, she learned everything from home repairs to design, and wants to share her tips with you. When she's not writing, she's usually hiking or searching for her next DIY project.

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