I recently bought this house. It has a new furnace that was installed a year ago. I have two six inch cold air ducts that vent to the north side of my house. Both cold air lines are not plumbed into the cold air intake on the furnace, they just basically hang in the rafters of my basement. The furnace has an exhaust line that is plumbed and goes outside. It also has a cold air intake on the front top that also could be plumbed to go somewhere but it wasn't. My issues is that these ducts are bringing in quite abit of cold air and my basement is freezing. I know some air needs to be brought in to prevent backdraft, but should one of these be capped or reduced and tied into the cold air intakes.