After some colder nights (15F) and not being able to raise the room temp barely with the blower on high, I finally broke down and put up a block off plate. Will see how it goes tonight! With the oversized cast faceplate, was easy to lift the top piece off and had enough access with a right-angle drill. The outer diameter of the liner when it comes into the stove is 6", shouldn't it be more if the liner is insulated? I will know more in the spring when I clean the liner. I paid for an insulated liner.