Discovered water pooling out on to floor and dripping from within furnace--seemingly coming from furnace vent... there is quite a bit of rust that has formed which leads me to think its been going on for a while within the furnace but was not noticed till now after heavy rains, and the pooling outside the furnace... after spotting a tiny tear in sealant around furnace vent on roof and had that repaired.. thought that did the trick (was repaired on a rare rain free day here in PDX, OR) Seems that once the rain began again, the puddling and water inside furnace began again. This is a forced air gas furnace "weathermaker8000" I do not have air conditioning or a water heater that is in proximity to furnace. How would one determine if there was a furnace vent obstruction and could that be the cause of leakage.. I'm completely "mistified" due to the rain factor.