Hello, I'm about to install a direct vent gas insert into my existing masonry fireplace. I'll be doing a full reline for intake and exhaust. I've spoken to a lot of people about using a block-off plate, but everyone keeps saying no block-off plate is needed for a gas insert. Well after reading these forums, I am convinced I should use a block-off plate for efficiency, or at least some sort of insulation. That said, why put the block-off plate a couple inches above the insert? Can I just remove the damper and then make a smaller block-off plate to cover the damper opening (since that opening is much smaller)? Then I can just lay some insulation on top of the plate and the old damper opening. I understand the damper is a little higher up, so the insert will be heating more air, but is it really going to make much difference? Also, if the chimney is capped, will it make much of a difference if I don't use a block-off plate and just cram some insulation around the damper opening? Thanks all, this forum has been so helpful!