i have a DV25 model 2642 vermont castings direct vent stove. This is an old stove with no installation manual. All of the parts lists I can find are very poor. I need a manual or drawing that shows how to hook up the flue pipe to the flue outlet. Is there a flue collar that adapts the 4X6 double wall flue to the stove? The original installation just had the flue pipe laying loose on top of the flue outlet/reducing orifice which I consider dangerous.