Insulating Heatform walls

[Judd]

I plan on installing an insert this fall in my interior masonry fireplace which contains a Heatform metal liner box (which I will be having to cut to get the liner through). I have read a few threads about people placing Roxul on the Heatform or masonry walls. I understand that these are in exterior fireplaces to keep heat from escaping through the bricks to the outside world. I was wondering if anyone thought that there would be any benefit to lining the walls on an interior fireplace with a Heatform (longer burn times, more heat output, less transfer of heat up the Heatform metal into the bottom of the chimney, etc). I plan on installing a block off plate with insulation above it as well as an insulated chimney liner. It may sound like overkill, but I don't really want to pull the insert out in the future if I can do something now to make it work better. I appreciate your thoughts.

 

[begreen]

I would skip it. This won't increase burn time and the heat that the surrounding heatform and masonry absorb will slowly be released back into the house.