Question: Just a quick question on installing an Advantage Plus pellet insert. I have a larger fireplace, nothing out of the ordinary though. Looking into the FP, there is a 4" pipe, open to the front, that then does a 90 and exits through the left to the outside. I assume that this is for fresh air, so I can have a closed glass front on the FP. The opening for the pipe is around 18" from the front of the burn area opening. The pipe exits outside around 6" or so from the wall of the house (brick) and extends from the fireplace about 3-4" Can I use this to direct vent to the outside, or will I need to vent up the flu? The insert will have to vent through flex to reach the pipe, and the exhaust will have to travel the bends in the flex, as well as the 90. Answer: If this is a fresh air intake then it probably cannot be used to vent the insert. Since cold air was supposed to come in the pipe, it was not designed for hot exhaust. The exception might only be if you could remove the pipe and confirm that it is solid masonry around it (no combustibles)..even then the venting would have to match the manufacturers manual as far as turns, etc. Your other alternative, which I assume you counted on when purchasing the insert, was to vent it up the existing chimney (to the top) using a liner.