How to replace ductwork and install a return vent in an older house.

Where needed, remove existing ductwork.Attach the flexible air duct under the house to the metal vent box and return the air handler to its original position.Extra length can be added if the air duct isn't long enough.Attach a second air duct to the first by peeling back the insulation and then attaching it to a first section with duct tape.Roll on the outer layer after folding the insulation back in place.

Extra length can be added if the air duct isn't long enough.Attach a second air duct to the first by peeling back the insulation and then attaching it to a first section with duct tape.Roll on the outer layer after folding the insulation back in place.

Attach the entire length of the duct to the floor joists with plastic ties and keep it away from the ground.The box should be sealed with plastic ties to keep the connection between the duct and the box as tight as possible.Once everything is in place, clip the end of the ties, seal everything tight with aluminum tape, and burnish with a plastic rib.

The box should be sealed with plastic ties to keep the connection between the duct and the box as tight as possible.Once everything is in place, clip the end of the ties, seal everything tight with aluminum tape, and burnish with a plastic rib.

A wooden frame or housing is needed to hold the new vent in place.Cut the 2x4s to fit the opening.Put the new vent in place with the help of the frame.screw in place using 2 x 4 braces.

The gaps between the floor and the frame should be filled with an insulated duct board.Make sure the board fits on both sides of the frame by cutting it to size.If necessary, seal the vent with mastic adhesive cement, which is painted on, to prevent air escapes.

If necessary, seal the vent with mastic adhesive cement, which is painted on, to prevent air escapes.