Had a new 80% gas furnace installed and now we have a oil substance dripping down the heat duct that leads up threw the roof ( on to the basement floor). No odor, but seems to turn to a hard wax after awhile. Had the co. that installed it come check it out and they had no idea, said they never saw anything like it before and that it wasn't coming from the furnace . Its been dripping for about a month now( from the day it was installed) and doesn't seem to be showing any signs of letting up. Trying to find out if this is something to worry about or not??