I get up this morning and I can hear this pounding noise coming from inside the furnace. I pull the cover off it and I can't see anything that could making the noise. I follow the piping that runs over to the chimney...and that's where the noise is emanating from. I had a steel cap installed over the chimney vent years ago to keep the birds and other wildlife out. I have a one and a half storey house...and the chimney prolly rises another ten feet higher over the peak in the roof. I go outside and look up...and there's a woodpecker pounding on the steel cap I had installed. The drunken son of a whore! WTF!!!