Duct work collapsed
We are in the process of purchasing our first home. We found one that we liked, made an offer, and then got an ispection. The inspector has found that all the ducts which run through the slab in this one story house have sand in them and are collapsed or in the process of doing so. Some of the ducts are completely blocked. In addition to this the furnace and air system don't seem to be installed properly. Our inspector has recommended that we get a whole new heat and air system with new duct work to run overhead in the attic. The estimate he gave us on the report for this was 5,000.
Doesn't that seem low? What causes duct work to collapse in the first place? The home was built in 1979, so I know it is no spring chicken, but it is not THAT old! Also what the heck is a flue pipe? It says on the inspectors report that it is disconnected in the attic?