Every winter when there is a blowing snow, my ceilng gets wet at the same spot just below the furnace vent pipe. The air flow has been corrected and a roofer found no roof leaks. This only happens when there is a blowing snow and at the same place in the ceiling. This does not happen during rain storms. Help
Re: wet ceiling
Do you have another roof vent, for ventilation, in the same general area? Perhaps the snow is blowing through the roof vent, and when it melts, it just happens to find a low spot in the ceiling, resulting in the wet ceiling.
It sounds like it is just coincidence that the water appears close to your other vent pipe, when that is not the problem at all.
Good luck in your search.