Originally Posted by bervin306
check the placement of the logs. There should be a diagram in the book they need to be in a certain spot. If the flame is hitting the logs it will cause it to soot up. That is what I would start with.
Bervin is right. most people think the inserts are trouble free. But the arrangement of the logs is critical for the proper combustion. If not than carbon monoxide forms.
Fire place inserts are even more critical than furnaces in this regard and there are more things to go wrong that can cause monoxide. if that that soot build up was in a furnace i would be turning it off and condemning it.
I would STRONGLY suggest you get a pro who has training on your brand to give it the once over.
It could save your life.