We purchased a house about 10 years ago and since have found several significant problems. It was inspected as part of the purchase, and none of these issues were identified. One that I just noticed recently is that several rooms do not have return air vent ducts to the furnace. Some have registers that are not connected to the furnace and some do not have registers at all.
I have heard there is a way to run small (3”) hoses through the walls to correct this problem. Do you have any additional information on this topic? Thanks.