Heh, well I'll be carbon filtering it down my vents, gotto keep a low heat sig, an i figure i can save money/energy on heating if i pump hot air to the rest of the house this winter. the plants will keep me warmDucting for the heat system and central air should be the same system. If you are connected to the duct system, when the a/c or the heater come on they will push air through your exhaust and into your room. If you do tie in to your ductwork tie in to the cold air return. This is the intake for your a/c - furnace. And although there is a filter on the cold air return it is not sufficient for removing grow room odors.
You have to make sure u run your vent to the OUTAKE of the furnace (what goes out the chimney) if your gonna use the existing ductwork then use a Y instead of a T to tie into the duct.what about blowing air into the heater? will it blow out the pilot light?