Hi there, I’ve installed an older used rsf wood furnace in my shop. Looking for some advice on the damper system. I’m trying to figure out where the draft air enters the firebox. There is a round louvred air intake on the front underneath the main door. This is connected to a butterfly plate that is activated by a chain attached to my damper unit. My question is where does the air go once it passes thru the butterfly valve? I have cleaned out the firebox and cannot see any air vents or passages along the sides. Any ideas? I want to make sure everything is open and free of any blockages so it drafts properly. Thanks Dave