Paul i have seen this before, When the new high efficiency oil furnace came out and stack temps where about 300 moisture would form and seep through the walls of the chimney (Fast it was not lined) exactly like your pictures, Ask them what kind of furnace they had? Btw where was this taken , Just curious.
Hi Wayne, photo taken up here in Ontario. I will have to ask about previous furnace. Current one is gas, with its own vent. Thanks for the info, much appreciated.