Hello RIU, winter has set in and the hole in my window i was using for passive intake is pulling in too much cold air. when i cover the holes in the window my grow tents seem to suck air from the furnace and it sets off my carbon monoxide alarms. the tents are in the room right next to the furnace room, the furnace room also has the window im venting in and out of. anyone have ideas how i could get my passive intake hole closed safely?