Two years ago, we moved into a brand new house. In the basement, there is a fresh-air pipe. It simply dumps air from the outside into the basement. In the infinite wisdom of the builders, they placed this vent on the complete opposite side of the furnace. As a result, the basement is absolutely freezing in the winter. Even after finishing the basement walls (putting in fiberglass insulation with vapor barrier, and then drywall) the basement is better, but still freezing. It is because of this fresh-air intake. My kids play down there in the basement most of the winter, so I wanted it to warm up. When I block the fresh-air intake vent, the basement temperature is significantly improved. But I've been told this is a mistake. However, I've also noticed that in the cold-air return duct work in the basement that feeds back to the furnace, there is an insulated duct that leads directly outside. This vent is hooked into the cold-air duct work directly. Wouldn't this vent, then, serve the same purpose as the fresh-air intake? Shouldn't it pull in the fresh air directly into the cold-air return, and therefore make the fresh-air intake redundant? Ideally, I'd like to just remove the fresh-air intake entirely, relying on this other one. But perhaps that other vent serves a different purpose? I can't see what. My other option is to put in a whole new fresh-air intake that is actually near the furnace so that the cold air doesn't have to spread across the entire basement. Any thoughts?