How to Hook Up Vent Pipes for Gas Furnaces

Hooking up a vent pipe for a gas furnace is not difficult. With a gas furnace, you can use a B-vent system, a double-walled pipe designed specifically for installations such as a gas furnace or a water heater. When installing this type of venting system, it is important to check local building codes for the requirements in your jurisdiction. This type of venting system is not suitable for fireplaces or oil furnaces.

Installing a gas furnace vent is easy with the proper tools.

Step 1

Plan the route you will take for your vent installation. Note that since 90-degree elbows have a tendency to trap gases, most jurisdictions will not allow them. Plan your route accordingly, using 45-degree elbows instead. The best route is the one that follows the shortest path to the roof.

Step 2

Put on safety glasses and a respirator.

Step 3

Cut the holes required to go through the walls and ceiling, using a drill and hole saw. Push the draft vent over the opening on the top of the furnace. Install the first section of pipe to the draft vent. Continue adding sections of pipe by pushing one onto the next. Add elbows as necessary to complete the entire route.

Step 4

Place a fire stop on each side of the wall or ceiling that the vent pipe will pass through. Do not eliminate this step because it is important for safety. Cut a hole through the roof using a drill and hole saw. Place a fire stop in the opening and place an insulation shield on the fire stop. Install the pipe through the roof. Install metal flashing, as well as a collar, around the pipe where it exits the house. Cut the flashing as necessary to go around the opening of the roof, using the tin snips.

Step 5

Install a cap on the vent outside to keep birds and small animals from getting in. Install pipe strap at various locations throughout the vent route to secure the pipe, using drywall screws, drill and a screwdriver bit. Install the pipe strap every 24 inches to make it secure.

About the Author

John Rose has been writing professionally since 1981. Now contributing to various online publications, he specializes in auto repair, home maintenance and similar topics. Rose studied English at Frostburg State University.