I once heard someone mention heating their home with exhausted grow room air, and i just blew it off as over complicating things. Now that i have recieved my second light bill over $300(without growing!), i have had a change of heart. I know it's the heat pump, because in the hottest month last year the bill was less than $175.
There is an a/c floor vent near the wall in my g-room, i had planned on just covering it, but i was thinking about exhausting my air into it during the cold season. All of the ducting is under the floor in the crawl space, if that makes a difference.
If you have heard of, or have done this, please let me know what issues you have had and what you did to solve them.
Jdubs