You snap those vents shut, anxious to see your energy savings and looking forward to all that extra toastiness in other rooms. However, blocking a vent in an attempt to redirect heat, though commonly done, is actually ineffective and possibly even damaging to your HVAC system.
What can I use to cover a vent?
Find a collection of pictures, prints of your favorite art, award ribbons, or other small trinkets that can fit over the surface of the vent. Attach or tie the items to the slats or bars of your air vent to keep them secure. As you arrange these decorations, make sure that you're not covering the vent completely.
Is it OK to cover a heating vent?
You could damage the heat exchanger. If there's a buildup of pressure from air being pushed to covered vents, the low airflow could create problems with your heat exchanger, causing it to crack and lead to carbon monoxide emissions.2 oct 2017