How to Attach an Extra A/C Vent to the Bedroom

Access the area that is supplying the air conditioning. If the bedroom is on a second story, the air is probably coming from the attic. If the bedroom is on a first floor, the air supply may be coming through duct work in a closet. If the bedroom already has one vent in it, the nearest access point is from the first vent in the room.

Use a stud finder to locate the joists in the ceiling. Locate an area between floor joists to install your new vent.

Use a carpenter's square to draw the outline for your new vent in the location you mapped out. Use a spiral saw to cut out the area you outlined.

Access the floor where you cut the hole. This could be in the attic or a second-story closet. Build a 2-by-4-foot frame to mount the register box. Attach the frame to the floor joists with 3-inch wood screws.

Place the inner duct over the vent boot, which resembles a small stove vent. Wrap the duct with foil and an insulation jacket for a secure fit.

Drill 1/2-inch sheet metal screws into the vent boot to attach it to the wooden frame.

Use a starting collar to attach the new ductwork with the main duct work. Cut out the hole in the rigid air duct for the collar with a utility knife. Place the collar inside the rigid air duct. Flatten the tabs with your fingers so the rigid air duct holds the collar securely in place. Insert any screws or pins that came with the starting collar packaging.

Place the inner duct over the starting collar. Tape the duct in place with metal foil tape. Add a zip tie to secure the duct in place. Attach zip ties along every 5 feet of duct work. Do not tighten the zip ties too tightly or you will cause kinks to occur in the duct work.

Attach the register from the room below. Use the screws that come in the register's packaging to cover the hole and vent work.