I've just moved into a new house, and the ductwork in the basement has a bunch of 1" (or so) diameter holes in the bottom sides of the ducts -- they are usually at the ends or at junctions of ducts. I'm thinking they are about the size of the holes that I've seen in the house I grew up in that had old swing-arm dampers.
The house has a natl gas furnace with a heat pump.
Is it safe/smart for me to have these holes sealed? They do blow a warm air into the unfinished basement.
Thanks in advance for any help!