Televised ducts under slab floor. Ducts are concrete with metal couplings. Metal is slightly rusted and allowing sand to enter system at the joints. Suggest spin cast mortar then spray lining ducts with Duct Armor duct lining material.
Video inspection of under slab air ducts because of reduced air flow in front part of house. There is a blockage with the pipe collapsed reducing the flow of air. The pipe needs to be dug up and replaced with a new pipe. The rest of the system should be spray lined with Duct Armor Duct lining material.