Quote Originally Posted by SoCal gunner View Post
Great info here. I'm really hoping to avoid the fresh air return for the reasons you described (definitely do not want a whole second HVAC system for this room either). My water heater is in the garage and furnace is in the attic - any concerns there?

As for fireplace, I'll just have to not have a fire while I'm smoking.
In that case, I think you would be OK. They would each have their own independent combustion air source and exhaust outside of the living space. You might be OK on the fireplace if it is a direct vent with its own air source to the outside. These would have a sealed glass front and not open to the room.
Keep in mind, I am not a HVAC professional. I wouldn’t want anyone succumbing to carbon monoxide poisoning on my advice.

Make sure to post up what you do. I would love to see it and hear how it goes.