How to Install Forced Air Ducting Into an Existing Line


Forced air ducting allows the warm air from your furnace to be distributed throughout your home. Sometimes you may need to run a new duct. You may have remodeled and need air in a different location, or maybe the room isn't staying warm enough and you want to add another duct run to help it maintain temperature. While it looks challenging, it actually isn't that hard to install forced air ducting in an existing line of duct. Your local home improvement store will carry all the tools and materials you need.

Things You'll Need

  • Sheet metal ducting
  • Sheet metal elbows
  • Sheet metal tab collar
  • Tape measure
  • Dividers
  • 1/2-inch drill bit
  • Cordless drill
  • Aviation snips
  • Pipe crimper
  • Level
  • Hammer
  • Sheet metal screws
  • Work gloves
  • Determine where you want your ducting to start and end. Measure the distance in between and purchase all necessary ducting and fittings from your local home improvement store.

  • Use your dividers and mark out a circle on the existing ducting where your new ducting will tap into. For example, if your new ducting will be 6-inch diameter, mark out a 6-inch circle on the old ducting where the new ducting will tie into.

  • Drill a 1/2-inch hole within that circle to gain an access point for your aviation snips.

  • Follow the scribed line with your aviation snips and cut out the sheet metal "circle" and discard it. Depending on where the duct will tie into, you may need to cut the "circle" out in pieces.

  • Slide the tabbed portion of your sheet metal tab collar into your hole. Fold the tabs over to the inside of the existing ducting. This will hold the tab collar into the ducting.

  • Install the rest of your sheet metal ducting to where your new register will be.

Tips & Warnings

  • Try not to tap into new ducting close to where the duct turns or bends. You will get the best airflow by tapping in at least 3 feet from the nearest turn or bend.
  • Working with sheet metal ducting can be dangerous. Sheet metal ducting is extremely sharp and can cause severe cuts. Wear gloves at all times.

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  • Timothy Gonyo; Sheet Metal Workers Local #18; Milwaukee, WI
  • Photo Credit Jupiterimages/ Images
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