We are having our bathroom remodeled. I just realized yesterday what is different-- the 2x 10 inch heating duct in the floor is no longer there. The contractor got carried away taking out the existing tile and demolished the slab, some places to just an inch thick. They filled in with concrete, but apparently concreted over the floor duct and then tiled over it with ceramic tile. The duct is about 12 feet away from the main duct that runs down the center of the house. What types of problems can arise from having a 12 foot long dead end in my heating and cooling system? There is a ceiling vent to provide heat and air, so we don't need that, but it seems like we could have problems with mold, etc. Any advice will be appreciated.