Blocking A/C vents can be required to have a more energy efficient home. Hot air rises and in a two-story house the top floor is the hottest and the basement is coolest. The A/C does not necessarily need to be active in the basement. Closing the vents in the basement will force more cold air upstairs where it is needed. Unfortunately, simply closing the vents does not provide enough blockage.
Select which vents should be blocked.
Unscrew the vent cover. Remove the vent cover.
Shine a flashlight into the vent. Look for a swinging flap that closes inside the vent. Close this flap. It may not be visible and may need to be reached with your hand. This will still not completely block the vent from releasing cold air, however.
Insert an old towel or rag into the duct. The material should completely fill the space. This will stop the air from coming through.
Replace the vent cover. Repeat these steps with each additional vent.
- "HVAC - Heating, Ventilating, and Air Conditioning"; S. Don Swenson; 2003
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