Hi,
I've got a couple of old furnace ducts near the ceiling in a couple of rooms in the house. I've since had new ducts put in the floor, and these upper ducts were simply closed off (but not sealed).
It's time to repaint, and I'd like to close up the upper ducts permanently and plaster over the openings. I figure I'll have to seal them off some way; otherwise I'll end up pumping hot air into the walls and eventually into the attic. That would be a bad thing, as I live in Canada. Probably a bad thing anywhere...
So, my question is, what is the best way to seal up these ducts? Is there something I can spray into them to block the air flow? There is really nowhere that I can apply metal tape.
Thanks.