The house we bought a couple of years ago has fairly new flexible insulated ducting going to the floor registers. While in the basement I can see that the ducting is held between the floor joist with flat metal straps. I'd say the ducts are about half pinched off in five or six places each. How much will this affect my heat and air bill? A lot, or a little? The house never gets really cool. Could this be part of the problem? Thanks