How to Build Your Own Cold Air Return

Select locations for the vents. The vents are typically located near the ground, either on the floor or a lower part of the wall. This is because hot air rises and cold air is closer to the ground. The locations should be close to hallow walls or in places of the house that will make running to duct to the vent easy.

Connect a square duct section to the cold air return on the furnace. Duct comes in sections that fit onto each other. Once a second section is connected, use a drill and screws to connect them. Run the duct upward. Attach a Y or four-way connector duct for the number of vents there will be. For example, a two story house with a basement will have a four-way connector. One for the top floor, one for the main floor, one for the basement and one leading to the furnace.

Run duct work from the connector to each of the vent locations. This can be tricky, try to run the duct between walls, if possible. Connect the duct panels to the walls and ceiling using mounts. The mount wraps around the duct work and is screwed into the wall/ceiling. Do this every few feet, where support is required.

Measure the size of the vent cover on the location where the vents will go. Cut out the floor or wall. Attach the duct work to the floor or wall. Add a vent cover to the duct work.

Turn on the furnace and test the system.