I built an office attached to my garage but not connected to my living space in my house. I tapped into my familyroom heating ductwork, (which had two vents and was always the hottest part of house in winter and coolest part in summer) and ran insulated flexible duct work to my office. When the door is opened from my office to the garage just a crack, and the heat is on it blows great, but when everything is shut up, it barely comes out. I realize that I have no cold air return in this isolated room, and am curious as to how I tap into the existing cold air return system. Are there certain fittings that I can use, do I cut into return at a certain place? My return system vent for the house is placed in my hallway in the ceiling. My house is single story.
Hope this makes sense. Thanks