[laserglass]

when you narrowed the duct to 6 inches, that is the issue....since you did this, you might as well have run it all with 6 inches....make up duct should always be larger than the vent duct....but an open window directly to the outside in the room should work fine for your duct.....just remember, you are bringing in outside air, so when its cold or hot as hell outside, that's what you are bringing in.... a heat exchanger in your make up air duct would help with this.... the bucket at the end of a tube hood that was shown in the photo, is a poor design for a vent hood....to tall off the work surface, no side or back baffles....yes incense will go up it but put the incense where the torch will be, and light it in place with your ventilation running, not before hand.... do not worry about where the smoke goes, can you smell the incense at all???? if so your ventilation needs work....