I had my entire roof replaced in 2009. I paid the same company to replace my chimney stack with a new galvanized chimney stack. Someone from the same roofing company was just out to look at a leak I had after a storm - small amount of water ran down waste pipe. He sealed around the pipe but told me I should consider getting a B vent for my heat line because I only have foil wrapped around it. He told me the cover over it was white and it should be galvanized. Is a B vent the same thing as a chimney stack? Is there a chance that they removed the rotted stack but didn't replace it with a new galvanized stack? Thanks.