I was reading in another thread about a suggestion to insulate the chimney opening in a fireplace insert application. How many other members with inserts have blocked off the bottom of their chimney with insulation? I'm just wondering if this is something necessary, as the installer did not block it off or suggest that I might want to do it. Are there any special considerations one should take in doing this, or reasons not to? I would be concerned about insulating around the stainless liner, for one... If it is recommended to, do you just use paperless fiberglass batting?