You can seal the air vents in a house to redirect the flow. Air vents can be located throughout a house to heat and cool individual rooms. Energy from a home heating and cooling system is wasted on unused rooms. Many vents are covered by slotted registers that direct the flow of the exiting air. Closing the slots on the vent register stops some of the air flow, but does not completely seal the vent.
Remove the screws on the sides of the vent register. Pull out the register. Set the screws and vent register aside to be reinstalled later.
Trim a piece of corrugated cardboard to the size of the vent opening. Press half the width of duct tape strips onto all four edges of the cardboard pieces.
Turn off the fan in the heating and cooling system. Hold the cardboard piece in place over the vent opening. Press the other half of the width of the duct tape onto the wall area surrounding the vent.
Secure the vent seal with another strip of duct tape on all four sides. Press half the width of each strip onto the first piece of duct tape and the other half onto the bare wall. Smooth all the duct tape onto the surface of the wall.
Turn the fan back on to test the vent seal. Hold your hand near the sides of the vent to feel for escaping air. Tape over the cardboard piece and farther onto the walls until the air leak is stopped.
Reinstall the vent register.
The cardboard lends structural support to the vent seal. Thin sheets of plastic or wood works just as well. Cut vent covers can be removed and reused as needed.