I live in a very old house with little insulation. As a result the furnace runs almost constantly in the winter, and the ac in the summer. I dont plan on being in this house forever, so I'm willing to live with that.
However, when the furnace/AC is runnng, the cold air return is extremely noisy - like a harriet jet about to take off. There are 3 cold air returns in the house - 2 are not working. The 1 cold air return which is working is located directly above the furnace. It is located in the living room and the furnace is right below it.
What is making it so noisy and what can I do to correct the problem? If the 2 non working cold air returns are fixed, will this reduce the noise level? I dont think the problem is with the furnace, since the air conditioning has the same problem.
Do I need new ductwork?