i have a house on a slab foundation. the heating ducts are clay tile and made into the slab. with heavy rains or a large melting snow the ducts fill about half full with water and of course when the furnace turns on it blows condensation all over the walls. i have already dug out and sealed the foundation which didn't help at all. does anyone know how i would go about finding where the water is coming from???? please help!!