How can I seal my registers?

Question

My furnace/AC is in my basement. I close my registers during off seasons (close the top ones in the winter, bottom ones in the summer), but it does very little to prevent air from blowing in those rooms. This is especially bad in the summer. There are 2 registers IN my basement, and at least 8 others on our lower levels that I would also like closed. But since the basement registers are 30-50 feet from the blower, a lot of AC is being wasted in my basement, even though they're "closed." Any suggestions on what I can do to completely seal those registers during the summer months?

Answer 1

Duct tape cardboard on the inside of the register grill cover.

Answer 2

I used to take a plastic bag and stuff it into the duct behind the register. Then, when the fan started blowing, it would push the bag out to the register and the plastic would seal it off.

I also have a register in my bedroom that blows directly on my bed. It blows quite hard when the fan is on and I would get chilled at night. So, I used strips of blue painter's tape to seal off the side of the register that blows toward the bed.

Answer 3

At the crafts store you can buy sheets of magnetic backing material like you would use to make refrigerator magnets.    Cut this to the size of you registers.  Magnetic attraction holds them in place without tape.