I am looking for a simple draft inducer solution for my boiler with double wall pipe. Based on my loading opportunities, I often feed the fire when there is still wood left, so I have smoke when I open the loading door. Waiting until it is almost burned out is not an option. My exhaust is double wall pipe in the room connecting to triple wall in the attic and above the roof. Out of the back of the boiler I have a Tee with exhaust above, automatic damper horizontal and cleanout cover on the bottom. I was thinking of a Venturi system where I put a length of 1 1/4 or 1 1/2 copper pipe (have some left over from plumbing) about three feet up the flue through the bottom plate, then attaching a 4" 200 CFM draft inducer fan (4" Inline Duct Fan model M-4) to the lower end of the pipe. I would turn this on when loading (I don't have any induction problems when starting). 4" fan cost is $75 on ebay. Does anyone think this will work? By physics it ought to work but reality often interferes with pure physics ;-)