The cold room is farthest from the furnace. All ductwork is in a crawl space which is not insulated but not cold. The cold room shares a return with the adjoining room. There is a 3/4 inch gap under the door which allows some air to return to the common areas of the house. Would a constantly running fan help? Is there a good strategy to moderating the heat in the house/ improving the airflow to/from this room?