[Stoves] Stack question

[Frank Shields]

Just wondering…

If you have a fan at the bottom blowing air into a stove and have a leak in the stack smoke goes out into the room.
If you have the fan at the top sucking air up and have a leak in the stack no smoke goes into the room. 

What happens if you have natural draft in the stack? A hole in the stack will let smoke into the room or will room air be sucked into the stack?


Thanks

Frank